[Demangle] Add support for D programming language

[ljmf00]

Summary

This is part of https://github.com/dlang/projects/issues/81 .

This patch adds support for D programming language demangling on LLVM core by
porting libiberty D demangler to LLVM C++ codebase. This will allow easier
integration on a future LLDB plugin for D either in the upstream tree or
outside of it. It also includes tests and a fuzzer tool.

Signed-off-by: Luís Ferreira <[e-mail]>

[dblaikie]

As with the Rust demangling (check the commit history, it was done earlier this year), I think this'd be easier to review if it were implemented incrementally - it'll be easier to spot the test coverage for each feature as it's added. Otherwise it's a lot of code to try to validate in one piece.

[ljmf00]

In D110576#3027009, @dblaikie wrote:

As with the Rust demangling (check the commit history, it was done earlier this year), I think this'd be easier to review if it were implemented incrementally - it'll be easier to spot the test coverage for each feature as it's added. Otherwise, it's a lot of code to try to validate in one piece.

Well, this is actually a port so it is harder to split up and the logic is well refactored since it is split up according to D mangling ABI nodes. I can split this into independent ABI nodes and incrementally add features like template demangling, although this will radically increase work on my side since I need to manually rewrite it to be incrementally independent patches.

About the coverage, I can't find where the coverage is officially reported. https://llvm.org/reports/coverage/ points to a very outdated report.

[Geod24]

In D110576#3027009, @dblaikie wrote:

As with the Rust demangling (check the commit history, it was done earlier this year), I think this'd be easier to review if it were implemented incrementally - it'll be easier to spot the test coverage for each feature as it's added. Otherwise it's a lot of code to try to validate in one piece.

I'll try to provide a bit more verbose background into the contribution:

This is a port of libiberty's D demangler as some comments mention, which was written by Iain Buclaw, the maintainer of GDC (GCC-based D compiler).
We have been in frequent communication with him before the project started and he has no issue with this code being used (and re-licensed) by LLVM. If any document / proof is needed on that side, please let us know.
As the code is part of libiberty, it is the backbone used to demangle D symbols in binutils since v2.25 (released 2014-12-23, see https://forum.dlang.org/thread/[e-mail] for the D-targeted announcement) and GDB.

As such, we're also pretty confident that it is quite robust and covers most, if not all, of D feature. As Luis mentioned, if breaking it down is unavoidable for the purpose of moving forward, then it will be, but that sounds counter-productive.

As for me, I am Luis' mentor during his Symmetry Autumn of Code time (a program similar to Google Summer of Code). The rough milestones / description of the project is also available here, as mentioned in the OP.

[dblaikie]

In D110576#3029264, @Geod24 wrote:

In D110576#3027009, @dblaikie wrote:

As with the Rust demangling (check the commit history, it was done earlier this year), I think this'd be easier to review if it were implemented incrementally - it'll be easier to spot the test coverage for each feature as it's added. Otherwise it's a lot of code to try to validate in one piece.

I'll try to provide a bit more verbose background into the contribution:

This is a port of libiberty's D demangler as some comments mention, which was written by Iain Buclaw, the maintainer of GDC (GCC-based D compiler).
We have been in frequent communication with him before the project started and he has no issue with this code being used (and re-licensed) by LLVM. If any document / proof is needed on that side, please let us know.
As the code is part of libiberty, it is the backbone used to demangle D symbols in binutils since v2.25 (released 2014-12-23, see https://forum.dlang.org/thread/[e-mail] for the D-targeted announcement) and GDB.

As such, we're also pretty confident that it is quite robust and covers most, if not all, of D feature. As Luis mentioned, if breaking it down is unavoidable for the purpose of moving forward, then it will be, but that sounds counter-productive.

As for me, I am Luis' mentor during his Symmetry Autumn of Code time (a program similar to Google Summer of Code). The rough milestones / description of the project is also available here, as mentioned in the OP.

I think this is roughly the same situation as was true with Rust: https://reviews.llvm.org/D99981#2837256 - but I think in that case and in this one, it'd be good to break it down to better validate the code against LLVM's coding conventions and other code review scrutiny.

[dblaikie]

In D110576#3034731, @dblaikie wrote:

In D110576#3029264, @Geod24 wrote:

In D110576#3027009, @dblaikie wrote:

As with the Rust demangling (check the commit history, it was done earlier this year), I think this'd be easier to review if it were implemented incrementally - it'll be easier to spot the test coverage for each feature as it's added. Otherwise it's a lot of code to try to validate in one piece.

I'll try to provide a bit more verbose background into the contribution:

This is a port of libiberty's D demangler as some comments mention, which was written by Iain Buclaw, the maintainer of GDC (GCC-based D compiler).
We have been in frequent communication with him before the project started and he has no issue with this code being used (and re-licensed) by LLVM. If any document / proof is needed on that side, please let us know.
As the code is part of libiberty, it is the backbone used to demangle D symbols in binutils since v2.25 (released 2014-12-23, see https://forum.dlang.org/thread/[e-mail] for the D-targeted announcement) and GDB.

As such, we're also pretty confident that it is quite robust and covers most, if not all, of D feature. As Luis mentioned, if breaking it down is unavoidable for the purpose of moving forward, then it will be, but that sounds counter-productive.

As for me, I am Luis' mentor during his Symmetry Autumn of Code time (a program similar to Google Summer of Code). The rough milestones / description of the project is also available here, as mentioned in the OP.

I think this is roughly the same situation as was true with Rust: https://reviews.llvm.org/D99981#2837256 - but I think in that case and in this one, it'd be good to break it down to better validate the code against LLVM's coding conventions and other code review scrutiny.

Not sure I'd say it's mandatory - other folks might have other opinions/perspectives/framing, but I tend to think it's the right way to go. (@jhenderson @rnk)

[jhenderson]

Whilst I appreciate that it'd require a fair bit of extra work, I'm inclined to agree with @dblaikie. I don't see any exception in the contribution policy (https://llvm.org/docs/Contributing.html#how-to-submit-a-patch) for larger ports. In particular, I'm pretty sure other even larger-scale contributions from a pre-done area have had to undergo this process, so it's not a new thing.

IANAL, but re. the relicensing, I guess we need some sort of formal agreement that the original author is happy for the relicensing, especially if any breakdown isn't going to end up with a significant rewrite. I suspect you should contact the LLVM board to discuss it.

One other minor point, please make sure to create patches with full context (i.e. add something like -U999999 to the patch-creation command line).

[dblaikie]

In D110576#3035742, @jhenderson wrote:

Whilst I appreciate that it'd require a fair bit of extra work, I'm inclined to agree with @dblaikie. I don't see any exception in the contribution policy (https://llvm.org/docs/Contributing.html#how-to-submit-a-patch) for larger ports. In particular, I'm pretty sure other even larger-scale contributions from a pre-done area have had to undergo this process, so it's not a new thing.

IANAL, but re. the relicensing, I guess we need some sort of formal agreement that the original author is happy for the relicensing, especially if any breakdown isn't going to end up with a significant rewrite. I suspect you should contact the LLVM board to discuss it.

Oh, yeah, thanks for pointing that out - ideally the original author would chime in on this thread and state that they're contributing this work to the LLVM project.

[ljmf00]

In D110576#3035742, @jhenderson wrote:

Whilst I appreciate that it'd require a fair bit of extra work, I'm inclined to agree with @dblaikie. I don't see any exception in the contribution policy (https://llvm.org/docs/Contributing.html#how-to-submit-a-patch) for larger ports. In particular, I'm pretty sure other even larger-scale contributions from a pre-done area have had to undergo this process, so it's not a new thing.

IANAL, but re. the relicensing, I guess we need some sort of formal agreement that the original author is happy for the relicensing, especially if any breakdown isn't going to end up with a significant rewrite. I suspect you should contact the LLVM board to discuss it.

One other minor point, please make sure to create patches with full context (i.e. add something like -U999999 to the patch-creation command line).

I'm already partitioning this patch. When everything is arranged I'm going to post some context here. A small question: should I abandon this patch or just override the diff with a minimal implementation and stack the other patches behind?

About the licensing, should I post a thread on https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev mailing list or anywhere else? Should I CC anyone in specific too, besides Mathias and Iain?

I passed that flag on the other patches, on the latest update I forgot to add it tho, although I'm aware of that.

[dblaikie]

In D110576#3037770, @ljmf00 wrote:

In D110576#3035742, @jhenderson wrote:

Whilst I appreciate that it'd require a fair bit of extra work, I'm inclined to agree with @dblaikie. I don't see any exception in the contribution policy (https://llvm.org/docs/Contributing.html#how-to-submit-a-patch) for larger ports. In particular, I'm pretty sure other even larger-scale contributions from a pre-done area have had to undergo this process, so it's not a new thing.

IANAL, but re. the relicensing, I guess we need some sort of formal agreement that the original author is happy for the relicensing, especially if any breakdown isn't going to end up with a significant rewrite. I suspect you should contact the LLVM board to discuss it.

One other minor point, please make sure to create patches with full context (i.e. add something like -U999999 to the patch-creation command line).

I'm already partitioning this patch. When everything is arranged I'm going to post some context here. A small question: should I abandon this patch or just override the diff with a minimal implementation and stack the other patches behind?

I think what was done with the Rust thread made sense - keep this one as-is (repurposing patches that change too much can make the overall review confusing, etc) - either abandoning it now, or waiting until all the work is otherwise committed - and then following up on this patch either way, with a list of the reviews/patches that implemented the functionality (& abandoning this patch at that point, if not done previously). Reference this patch in the other patches for context, to give an overview, etc.

About the licensing, should I post a thread on https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev mailing list or anywhere else? Should I CC anyone in specific too, besides Mathias and Iain?

Having the original author reply to this patch with their affirmative consent to contribute this work under LLVM's licensing, should be enough for me.

[jhenderson]

In D110576#3037770, @ljmf00 wrote:

About the licensing, should I post a thread on https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev mailing list or anywhere else? Should I CC anyone in specific too, besides Mathias and Iain?

I don't think it'd hurt to post on the llvm-dev mailing list anyway, probably CC'ing someone like Tanya Lattner, who can point you in the right direction of anything specific. Posting it there also has the added benefit of getting more attention to your patch series - I'd hold off posting until you've posted the first few patches on Phabricator, and then you can link to them in the email thread. Alternatively, send the email now and just follow up with the links in a later email on the same thread.

[ljmf00]

In D110576#3039261, @jhenderson wrote:

In D110576#3037770, @ljmf00 wrote:

About the licensing, should I post a thread on https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev mailing list or anywhere else? Should I CC anyone in specific too, besides Mathias and Iain?

I don't think it'd hurt to post on the llvm-dev mailing list anyway, probably CC'ing someone like Tanya Lattner, who can point you in the right direction of anything specific. Posting it there also has the added benefit of getting more attention to your patch series - I'd hold off posting until you've posted the first few patches on Phabricator, and then you can link to them in the email thread. Alternatively, send the email now and just follow up with the links in a later email on the same thread.

I finished the patch split. I tried to minimize dependent code, and end up with this list:

https://reviews.llvm.org/D111414
https://reviews.llvm.org/D111415
https://reviews.llvm.org/D111416
https://reviews.llvm.org/D111417
https://reviews.llvm.org/D111419
https://reviews.llvm.org/D111420
https://reviews.llvm.org/D111421
https://reviews.llvm.org/D111422
https://reviews.llvm.org/D111423
https://reviews.llvm.org/D111424
https://reviews.llvm.org/D111425
https://reviews.llvm.org/D111426
https://reviews.llvm.org/D111428
https://reviews.llvm.org/D111429
https://reviews.llvm.org/D111430
https://reviews.llvm.org/D111431
https://reviews.llvm.org/D111432

All patches are compiled independently if stacked correctly. I'm going to write to the mailing list CCing Tanya Lattner and referencing this diff for some context.

[jhenderson]

I'd be happy to help review this stack at some point - I find demangling interesting, but I'd need a spec to refer to, to help confirm correctness, and cannot confirm I'll have masses of time to do it.

Please either subscribe me or add me as a reviewer to the patches in the patch series if they're ready for review, and I'l take a look at some point, if nobody else does.

[jblachly]

In D110576#3054311, @jhenderson wrote:

I'd be happy to help review this stack at some point - I find demangling interesting, but I'd need a spec to refer to, to help confirm correctness, and cannot confirm I'll have masses of time to do it.

Please either subscribe me or add me as a reviewer to the patches in the patch series if they're ready for review, and I'l take a look at some point, if nobody else does.

https://dlang.org/spec/abi.html#name_mangling

[ibuclaw]

In D110576#3037774, @dblaikie wrote:

In D110576#3037770, @ljmf00 wrote:

About the licensing, should I post a thread on https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev mailing list or anywhere else? Should I CC anyone in specific too, besides Mathias and Iain?

Having the original author reply to this patch with their affirmative consent to contribute this work under LLVM's licensing, should be enough for me.

Hi @dblaikie, I'm the author of libiberty/d-demangle.c. I'm aware of the SAoC project for this work, and am supportive of it. To be sure, I also ran a question past the copyright clerk at FSF as well, who confirmed that I have worldwide rights to use my contributions as I see fit, including relicensing them.

[dblaikie]

In D110576#3059757, @ibuclaw wrote:

In D110576#3037774, @dblaikie wrote:

In D110576#3037770, @ljmf00 wrote:

About the licensing, should I post a thread on https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev mailing list or anywhere else? Should I CC anyone in specific too, besides Mathias and Iain?

Having the original author reply to this patch with their affirmative consent to contribute this work under LLVM's licensing, should be enough for me.

Hi @dblaikie, I'm the author of libiberty/d-demangle.c. I'm aware of the SAoC project for this work, and am supportive of it. To be sure, I also ran a question past the copyright clerk at FSF as well, who confirmed that I have worldwide rights to use my contributions as I see fit, including relicensing them.

Thanks!

[MaskRay]

llvm/lib/Demangle/DLangDemangle.cpp

1862

For a block comment, // is preferred as well. https://llvm.org/docs/CodingStandards.html#comment-formatting

[rsmith]

In D110576#3029264, @Geod24 wrote:

This is a port of libiberty's D demangler as some comments mention, which was written by Iain Buclaw, the maintainer of GDC (GCC-based D compiler).
We have been in frequent communication with him before the project started and he has no issue with this code being used (and re-licensed) by LLVM. If any document / proof is needed on that side, please let us know.

Is the consent of @ibuclaw sufficient? According to github, there have been seven contributors to this code: https://github.com/gcc-mirror/gcc/blob/master/libiberty/d-demangle.c. In addition to @ljmf00 and @ibuclaw, they are: (github usernames) bobsayshilol, jakubjelinek, rainers, brobecke, amodra

[ljmf00]

In D110576#3062467, @rsmith wrote:

In D110576#3029264, @Geod24 wrote:

This is a port of libiberty's D demangler as some comments mention, which was written by Iain Buclaw, the maintainer of GDC (GCC-based D compiler).
We have been in frequent communication with him before the project started and he has no issue with this code being used (and re-licensed) by LLVM. If any document / proof is needed on that side, please let us know.

Is the consent of @ibuclaw sufficient? According to github, there have been seven contributors to this code: https://github.com/gcc-mirror/gcc/blob/master/libiberty/d-demangle.c. In addition to @ljmf00 and @ibuclaw, they are: (github usernames) bobsayshilol, jakubjelinek, rainers, brobecke, amodra

A few additions to your comment:

• jakubjelinek: updated copyright headers only (not eligible here)
• the change introduced with brobecke was reverted by ibuclaw on https://github.com/gcc-mirror/gcc/commit/fd91ffb8051c3a99b8fdffa1c6234f9f884fce1c#diff-b3f1a0056a0bc5c69d189e9f60fd8b03c22b08d4343c745e3d914461c646fbc6 (not eligible here)
• changes introduced by rainers was co-authored with ibuclaw (see: https://github.com/gcc-mirror/gcc/commit/3f30a274913bde0a1e01a86ce7c85e3be34ea13f#diff-b3f1a0056a0bc5c69d189e9f60fd8b03c22b08d4343c745e3d914461c646fbc6)
• rainers is part of the D Programming Language organization
• the copyright notice on the file header, only mention Written by Iain Buclaw ([e-mail])
• changes introduced by amodra and bobsayshilol was relatively small (avg 50 lines of code, equivalent to 2 to 3% of the code)

Please note that I'm not saying that small contributions are not eligible for relicensing, just stating that fact, for further appreciation, if eligible.

llvm/lib/Demangle/DLangDemangle.cpp

1862

I'll address that, however, if find anything more like that, please review on the split patches, please, otherwise I can loose track of it more easily.

[ljmf00]

I'm going to abandon this revision since it is has superseded by the list of patches I mentioned above.

[• galapoz1996]

This comment was removed by mehdi_amini.

llvm/include/llvm/Demangle/Demangle.h

 // Demangles a Rust v0 mangled symbol. The API follows that of __cxa_demangle.
 char *rustDemangle(const char *MangledName, char *Buf, size_t *N, int *Status);
 
+// Demangles a D mangled symbol
+char *dlangDemangle(const char *MangledName);
+
 /// Attempt to demangle a string using different demangling schemes.
 /// The function uses heuristics to determine which demangling scheme to use.
 /// \param MangledName - reference to string to demangle.

llvm/lib/Demangle/CMakeLists.txt

   MicrosoftDemangle.cpp
   MicrosoftDemangleNodes.cpp
   RustDemangle.cpp
+  DLangDemangle.cpp
 
   ADDITIONAL_HEADER_DIRS
   "${LLVM_MAIN_INCLUDE_DIR}/llvm/Demangle"

llvm/lib/Demangle/DLangDemangle.cpp

+//===--- DLangDemangle.cpp -------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines a demangler for D programming language as specified in the
+/// ABI specification, available at:
+/// https://dlang.org/spec/abi.html#name_mangling
+///
+//===----------------------------------------------------------------------===//
+//
+// Ported from libiberty library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Demangle/Demangle.h"
+#include "llvm/Demangle/MicrosoftDemangleNodes.h"
+
+#include <cassert>
+#include <cctype>
+#include <cstdlib>
+#include <cstring>
+#include <limits.h>
+
+using namespace llvm;
+
+namespace {
+
+/// A mini string-handling class for output strings generated by D demangler
+///
+/// \note Beware these aren't required to be '\0' terminated
+struct OutputString {
+
+  /// pointer to start of string
+  char *Buffer;
+  /// pointer after last character
+  char *Ptr;
+  /// pointer after end of allocated space
+  char *EndPtr;
+
+public:
+  /// Constructs a new output string
+  OutputString();
+
+  /// Free resources previously allocated to the Buffer
+  void free();
+
+  /// Get the current length of the string
+  int getLength();
+
+  /// Set a given new length to the string
+  ///
+  /// \param Size new length
+  void setLength(int Size);
+
+  /// Append a given single char to the string
+  ///
+  /// \param C char to append
+  void append(char C);
+
+  /// Append a given input to the string
+  ///
+  /// \param Str input string to append
+  void append(const char *Str);
+
+  /// Append a given input with a specific length to the string
+  ///
+  /// \param Str input string to append
+  /// \param Size length to append from the given input string
+  void append(const char *Str, size_t Size);
+
+  /// Prepend a given input to the string
+  ///
+  /// \param Str input string to prepend
+  void prepend(const char *Str);
+
+  /// Prepend a given input with a specific length to the string
+  ///
+  /// \param Str input string to prepend
+  /// \param Size length to prepend from the given input string
+  void prepend(const char *Str, size_t Size);
+
+private:
+  /// Allocate more needed space to the Buffer
+  ///
+  /// \param Size size of the space needed
+  void need(size_t Size);
+};
+
+/// Demangle information structure
+struct Demangler {
+  /// Initialize the information structure we use to pass around information
+  ///
+  /// \param Mangled String to demangle
+  Demangler(const char *Mangled);
+
+  /// Extract and demangle the mangled symbol and append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#name_mangling
+  /// \see https://dlang.org/spec/abi.html#MangledName
+  const char *parseMangle(OutputString *Decl);
+
+private:
+  /// Extract and demangle a given mangled symbol and append it to the output
+  /// string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#name_mangling
+  /// \see https://dlang.org/spec/abi.html#MangledName
+  const char *parseMangle(OutputString *Decl, const char *Mangled);
+
+  /// Extract the number from a given string
+  ///
+  /// \param Mangled string to extract the number
+  /// \param Ret assigned result value
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \note A result larger than UINT_MAX is considered a failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Number
+  const char *decodeNumber(const char *Mangled, unsigned long *Ret);
+
+  /// Extract the hex-digit from a given string
+  ///
+  /// \param Mangled string to extract the hex-digit
+  /// \param Ret assigned result value
+  ///
+  /// \return the remaining string on success or nullptr on failure.
+  ///
+  /// \see https://dlang.org/spec/abi.html#HexDigits
+  const char *decodeHexdigit(const char *Mangled, char *Ret);
+
+  /// Extract the back reference position from a given string
+  ///
+  /// \param Mangled string to extract the back reference position
+  /// \param Ret assigned result value
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \note a result <= 0 is a failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#back_ref
+  /// \see https://dlang.org/spec/abi.html#NumberBackRef
+  const char *decodeBackrefPos(const char *Mangled, long *Ret);
+
+  /// Extract the symbol pointed by the back reference form a given string
+  ///
+  /// \param Mangled string to extract the back reference position
+  /// \param Ret assigned result value
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#back_ref
+  const char *decodeBackref(const char *Mangled, const char **Ret);
+
+  /// Extract and demangle backreferenced symbol from a given mangled symbol
+  /// and append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#back_ref
+  /// \see https://dlang.org/spec/abi.html#IdentifierBackRef
+  const char *parseSymbolBackref(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle backreferenced type from a given mangled symbol
+  /// and append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  /// \param IsFunction whether the backreferenced type is expected to be a
+  ///                   function
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#back_ref
+  /// \see https://dlang.org/spec/abi.html#TypeBackRef
+  const char *parseTypeBackref(OutputString *Decl, const char *Mangled,
+                               bool IsFunction);
+
+  /// Check whether it is a function calling convention
+  ///
+  /// \param Mangled string to extract the function calling convention
+  ///
+  /// \return true on success, false otherwise
+  ///
+  /// \see https://dlang.org/spec/abi.html#CallConvention
+  /// \see https://dlang.org/spec/abi.html#function_calling_conventions
+  bool isCallConvention(const char *Mangled);
+
+  /// Extract and demangle calling convention from a given mangled symbol and
+  /// append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#CallConvention
+  /// \see https://dlang.org/spec/abi.html#function_calling_conventions
+  const char *parseCallConvention(OutputString *Decl, const char *Mangled);
+
+  /// Check whether it is the beginning of a symbol name
+  ///
+  /// \param Mangled string to extract the symbol name
+  ///
+  /// \return true on success, false otherwise
+  ///
+  /// \see https://dlang.org/spec/abi.html#SymbolName
+  bool isSymbolName(const char *Mangled);
+
+  /// Extract and demangle an identifier from a given mangled symbol append it
+  /// to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#SymbolName
+  const char *parseIdentifier(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle the plain identifier from a given mangled symbol and
+  /// prepend/append it to the output string, with a special treatment for some
+  /// magic compiler generated symbols.
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  /// \param Len length of the mangled symbol name
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#LName
+  const char *parseLName(OutputString *Decl, const char *Mangled,
+                         unsigned long Len);
+
+  /// Extract and demangle the qualified symbol from a given mangled symbol
+  /// append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  /// \param SuffixModifiers true if we are printing the modifiers after the
+  ///                        symbol, false otherwise
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#QualifiedName
+  const char *parseQualified(OutputString *Decl, const char *Mangled,
+                             bool SuffixModifiers);
+
+  /// Extract and demangle the type modifiers from a given mangled symbol
+  /// append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#TypeModifiers
+  const char *parseTypeModifiers(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle the D function attributes from a given mangled
+  /// symbol append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#FuncAttr
+  const char *parseAttributes(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle the function type from a given mangled symbol
+  /// without the return type and append it to the arguments, calling
+  /// convention and attribute output strings, respectively.
+  ///
+  /// \param Args output buffer to write the demangled arguments
+  /// \param Call output buffer to write the demangled calling convention
+  /// \param Attr output buffer to write the demangled attributes
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \note Any of the output strings can be nullptr to throw the information
+  ///       away.
+  ///
+  /// \see https://dlang.org/spec/abi.html#TypeFunctionNoReturn
+  const char *parseFunctionTypeNoreturn(OutputString *Args, OutputString *Call,
+                                        OutputString *Attr,
+                                        const char *Mangled);
+
+  /// Extract and demangle the function type from a given mangled symbol
+  /// append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#TypeFunction
+  const char *parseFunctionType(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle the function arguments list from a given mangled
+  /// symbol append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Parameters
+  const char *parseFunctionArgs(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle a type from a given mangled symbol append it to
+  /// the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Type
+  const char *parseType(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle an integer value from a given mangled symbol append
+  /// it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  /// \param Type mangled type character in which the type should be
+  ///             represented as
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Value
+  const char *parseInteger(OutputString *Decl, const char *Mangled, char Type);
+
+  /// Extract and demangle a floating-point value from a given mangled symbol
+  /// append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Value
+  const char *parseReal(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle a string value from a given mangled symbol append it
+  /// to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Value
+  const char *parseString(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle an array literal value from a given mangled symbol
+  /// append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Value
+  const char *parseArrayLiteral(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle an associative array value from a given mangled
+  /// symbol append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Value
+  const char *parseAssocArray(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle an struct literal value from a given mangled symbol
+  /// append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  /// \param Name demangled symbol name of the struct literal
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Value
+  const char *parseStructLiteral(OutputString *Decl, const char *Mangled,
+                                 const char *Name);
+
+  /// Extract and demangle any value from a given mangled symbol append it to
+  /// the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  /// \param Name demangled symbol name of the type, if needed
+  /// \param Type mangled type character in which the type should be
+  ///             represented as, if needed
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#Value
+  const char *parseValue(OutputString *Decl, const char *Mangled,
+                         const char *Name, char Type);
+
+  /// Extract and demangle a tuple value from a given mangled symbol append it
+  /// to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#TypeTuple
+  const char *parseTuple(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle the template symbol parameter from a given mangled
+  /// symbol append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#TemplateArgX
+  const char *parseTemplateSymbolParameter(OutputString *Decl,
+                                           const char *Mangled);
+
+  /// Extract and demangle the template arguments list from a given mangled
+  /// symbol append it to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#TemplateArgs
+  const char *parseTemplateArgs(OutputString *Decl, const char *Mangled);
+
+  /// Extract and demangle a template from a given mangled symbol and append it
+  /// to the output string
+  ///
+  /// \param Decl output buffer to write the demangled name
+  /// \param Mangled mangled symbol to be demangled
+  /// \param Len expected characters length (default to -1 if unknown length)
+  ///
+  /// \return the remaining string on success or nullptr on failure
+  ///
+  /// \see https://dlang.org/spec/abi.html#TemplateInstanceName
+  const char *parseTemplate(OutputString *Decl, const char *Mangled,
+                            unsigned long Len = -1);
+
+  /// The string we are demangling.
+  const char *Str;
+  /// The index of the last back reference.
+  int LastBackref;
+};
+
+} // namespace
+
+void OutputString::need(size_t Size) {
+  size_t Temp;
+
+  if (Buffer == nullptr) {
+    if (Size < 32) {
+      Size = 32;
+    }
+    Ptr = Buffer = static_cast<char *>(std::malloc(Size));
+    EndPtr = Buffer + Size;
+  } else if (static_cast<size_t>(EndPtr - Ptr) < Size) {
+    Temp = Ptr - Buffer;
+    Size += Temp;
+    Size *= 2;
+    Buffer = static_cast<char *>(std::realloc(Buffer, Size));
+    Ptr = Buffer + Temp;
+    EndPtr = Buffer + Size;
+  }
+}
+
+OutputString::OutputString() : Buffer(nullptr), Ptr(nullptr), EndPtr(nullptr) {}
+
+void OutputString::free() {
+  if (Buffer != nullptr) {
+    std::free(Buffer);
+    Buffer = Ptr = EndPtr = nullptr;
+  }
+}
+
+int OutputString::getLength() {
+  if (Ptr == Buffer) {
+    return 0;
+  }
+  return Ptr - Buffer;
+}
+
+void OutputString::setLength(int Size) {
+  if (Size - getLength() < 0) {
+    Ptr = Buffer + Size;
+  }
+}
+
+void OutputString::append(char C) {
+  need(1);
+  *Ptr = C;
+  Ptr++;
+}
+
+void OutputString::append(const char *Str) { append(Str, strlen(Str)); }
+
+void OutputString::append(const char *Str, size_t Size) {
+  if (Size != 0) {
+    need(Size);
+    std::memcpy(Ptr, Str, Size);
+    Ptr += Size;
+  }
+}
+
+void OutputString::prepend(const char *Str) {
+  if (Str != nullptr && *Str != '\0') {
+    prepend(Str, strlen(Str));
+  }
+}
+
+void OutputString::prepend(const char *Str, size_t Size) {
+  char *TempBuffer;
+
+  if (Size != 0) {
+    need(Size);
+    for (TempBuffer = Ptr - 1; TempBuffer >= Buffer; TempBuffer--) {
+      TempBuffer[Size] = TempBuffer[0];
+    }
+    std::memcpy(Buffer, Str, Size);
+    Ptr += Size;
+  }
+}
+
+const char *Demangler::decodeNumber(const char *Mangled, unsigned long *Ret) {
+  // Return nullptr if trying to extract something that isn't a digit
+  if (Mangled == nullptr || !std::isdigit(*Mangled))
+    return nullptr;
+
+  unsigned long Val = 0;
+
+  while (std::isdigit(*Mangled)) {
+    unsigned long Digit = Mangled[0] - '0';
+
+    // Check for overflow.
+    if (Val > (UINT_MAX - Digit) / 10)
+      return nullptr;
+
+    Val = Val * 10 + Digit;
+    Mangled++;
+  }
+
+  if (*Mangled == '\0')
+    return nullptr;
+
+  *Ret = Val;
+  return Mangled;
+}
+
+const char *Demangler::decodeHexdigit(const char *Mangled, char *Ret) {
+  char C;
+
+  // Return nullptr if trying to extract something that isn't a hexdigit
+  if (Mangled == nullptr || !std::isxdigit(Mangled[0]) ||
+      !std::isxdigit(Mangled[1]))
+    return nullptr;
+
+  C = Mangled[0];
+  if (!std::isdigit(C))
+    *Ret = C - (std::isupper(C) ? 'A' : 'a') + 10;
+  else
+    *Ret = C - '0';
+
+  C = Mangled[1];
+  if (!std::isdigit(C))
+    *Ret = (*Ret << 4) | (C - (std::isupper(C) ? 'A' : 'a') + 10);
+  else
+    *Ret = (*Ret << 4) | (C - '0');
+
+  Mangled += 2;
+
+  return Mangled;
+}
+
+bool Demangler::isCallConvention(const char *Mangled) {
+  switch (*Mangled) {
+  case 'F':
+  case 'U':
+  case 'V':
+  case 'W':
+  case 'R':
+  case 'Y':
+    return true;
+
+  default:
+    return false;
+  }
+}
+
+const char *Demangler::decodeBackrefPos(const char *Mangled, long *Ret) {
+  // Return nullptr if trying to extract something that isn't a digit
+  if (Mangled == nullptr || !std::isalpha(*Mangled))
+    return nullptr;
+
+  /* Any identifier or non-basic type that has been emitted to the mangled
+     symbol before will not be emitted again, but is referenced by a special
+     sequence encoding the relative position of the original occurrence in the
+     mangled symbol name.
+     Numbers in back references are encoded with base 26 by upper case letters
+     A-Z for higher digits but lower case letters a-z for the last digit.
+        NumberBackRef:
+            [a-z]
+            [A-Z] NumberBackRef
+            ^
+   */
+  unsigned long Val = 0;
+
+  while (std::isalpha(*Mangled)) {
+    // Check for overflow
+    if (Val > (ULONG_MAX - 25) / 26)
+      break;
+
+    Val *= 26;
+
+    if (Mangled[0] >= 'a' && Mangled[0] <= 'z') {
+      Val += Mangled[0] - 'a';
+      if ((long)Val <= 0)
+        break;
+      *Ret = Val;
+      return Mangled + 1;
+    }
+
+    Val += Mangled[0] - 'A';
+    Mangled++;
+  }
+
+  return nullptr;
+}
+
+const char *Demangler::decodeBackref(const char *Mangled, const char **Ret) {
+  *Ret = nullptr;
+
+  if (Mangled == nullptr || *Mangled != 'Q')
+    return nullptr;
+
+  // Position of 'Q'
+  const char *Qpos = Mangled;
+  long RefPos;
+  Mangled++;
+
+  Mangled = decodeBackrefPos(Mangled, &RefPos);
+  if (Mangled == nullptr)
+    return nullptr;
+
+  if (RefPos > Qpos - Str)
+    return nullptr;
+
+  /* Set the position of the back reference.  */
+  *Ret = Qpos - RefPos;
+
+  return Mangled;
+}
+
+const char *Demangler::parseSymbolBackref(OutputString *Decl,
+                                          const char *Mangled) {
+  /* An identifier back reference always points to a digit 0 to 9.
+        IdentifierBackRef:
+            Q NumberBackRef
+            ^
+   */
+  const char *Backref;
+  unsigned long Len;
+
+  // Get position of the back reference
+  Mangled = decodeBackref(Mangled, &Backref);
+
+  // Must point to a simple identifier
+  Backref = decodeNumber(Backref, &Len);
+  if (Backref == nullptr || strlen(Backref) < Len)
+    return nullptr;
+
+  Backref = parseLName(Decl, Backref, Len);
+  if (Backref == nullptr)
+    return nullptr;
+
+  return Mangled;
+}
+
+const char *Demangler::parseTypeBackref(OutputString *Decl, const char *Mangled,
+                                        bool IsFunction) {
+  /* A type back reference always points to a letter.
+        TypeBackRef:
+            Q NumberBackRef
+            ^
+   */
+  const char *Backref;
+
+  /* If we appear to be moving backwards through the mangle string, then
+     bail as this may be a recursive back reference */
+  if (Mangled - Str >= LastBackref)
+    return nullptr;
+
+  int SaveRefPos = LastBackref;
+  LastBackref = Mangled - Str;
+
+  // Get position of the back reference
+  Mangled = decodeBackref(Mangled, &Backref);
+
+  // Must point to a type
+  if (IsFunction)
+    Backref = parseFunctionType(Decl, Backref);
+  else
+    Backref = parseType(Decl, Backref);
+
+  LastBackref = SaveRefPos;
+
+  if (Backref == nullptr)
+    return nullptr;
+
+  return Mangled;
+}
+
+bool Demangler::isSymbolName(const char *Mangled) {
+  long Ret;
+  const char *Qref = Mangled;
+
+  if (std::isdigit(*Mangled))
+    return true;
+
+  if (Mangled[0] == '_' && Mangled[1] == '_' &&
+      (Mangled[2] == 'T' || Mangled[2] == 'U'))
+    return true;
+
+  if (*Mangled != 'Q')
+    return false;
+
+  Mangled = decodeBackrefPos(Mangled + 1, &Ret);
+  if (Mangled == nullptr || Ret > Qref - Str)
+    return false;
+
+  return std::isdigit(Qref[-Ret]);
+}
+
+const char *Demangler::parseCallConvention(OutputString *Decl,
+                                           const char *Mangled) {
+  if (Mangled == nullptr || *Mangled == '\0')
+    return nullptr;
+
+  switch (*Mangled) {
+  case 'F': /* (D) */
+    Mangled++;
+    break;
+
+  case 'U': /* (C) */
+    Mangled++;
+    Decl->append("extern(C) ");
+    break;
+
+  case 'W': /* (Windows) */
+    Mangled++;
+    Decl->append("extern(Windows) ");
+    break;
+
+  case 'V': /* (Pascal) */
+    Mangled++;
+    Decl->append("extern(Pascal) ");
+    break;
+
+  case 'R': /* (C++) */
+    Mangled++;
+    Decl->append("extern(C++) ");
+    break;
+
+  case 'Y': /* (Objective-C) */
+    Mangled++;
+    Decl->append("extern(Objective-C) ");
+    break;
+
+  default:
+    return nullptr;
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseTypeModifiers(OutputString *Decl,
+                                          const char *Mangled) {
+  if (Mangled == nullptr || *Mangled == '\0')
+    return nullptr;
+
+  switch (*Mangled) {
+  case 'x': /* const */
+    Mangled++;
+    Decl->append(" const");
+    return Mangled;
+
+  case 'y': /* immutable */
+    Mangled++;
+    Decl->append(" immutable");
+    return Mangled;
+
+  case 'O': /* shared */
+    Mangled++;
+    Decl->append(" shared");
+    return parseTypeModifiers(Decl, Mangled);
+
+  case 'N':
+    Mangled++;
+    if (*Mangled == 'g') /* wild */
+    {
+      Mangled++;
+      Decl->append(" inout");
+      return parseTypeModifiers(Decl, Mangled);
+    }
+
+    return nullptr;
+
+  default:
+    return Mangled;
+  }
+}
+
+const char *Demangler::parseAttributes(OutputString *Decl,
+                                       const char *Mangled) {
+  if (Mangled == nullptr || *Mangled == '\0')
+    return nullptr;
+
+  while (*Mangled == 'N') {
+    Mangled++;
+    switch (*Mangled) {
+    case 'a': /* pure */
+      Mangled++;
+      Decl->append("pure ");
+      continue;
+
+    case 'b': /* nothrow */
+      Mangled++;
+      Decl->append("nothrow ");
+      continue;
+
+    case 'c': /* ref */
+      Mangled++;
+      Decl->append("ref ");
+      continue;
+
+    case 'd': /* @property */
+      Mangled++;
+      Decl->append("@property ");
+      continue;
+
+    case 'e': /* @trusted */
+      Mangled++;
+      Decl->append("@trusted ");
+      continue;
+
+    case 'f': /* @safe */
+      Mangled++;
+      Decl->append("@safe ");
+      continue;
+
+    case 'g':
+    case 'h':
+    case 'k':
+    case 'n':
+      /* inout parameter is represented as 'Ng'.
+         vector parameter is represented as 'Nh'.
+         return parameter is represented as 'Nk'.
+         typeof(*null) parameter is represented as 'Nn'.
+         If we see this, then we know we're really in the
+         parameter list.  Rewind and break.  */
+      Mangled--;
+      break;
+
+    case 'i': /* @nogc */
+      Mangled++;
+      Decl->append("@nogc ");
+      continue;
+
+    case 'j': /* return */
+      Mangled++;
+      Decl->append("return ");
+      continue;
+
+    case 'l': /* scope */
+      Mangled++;
+      Decl->append("scope ");
+      continue;
+
+    case 'm': /* @live */
+      Mangled++;
+      Decl->append("@live ");
+      continue;
+
+    default: /* unknown attribute */
+      return nullptr;
+    }
+    break;
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseFunctionTypeNoreturn(OutputString *Args,
+                                                 OutputString *Call,
+                                                 OutputString *Attr,
+                                                 const char *Mangled) {
+  OutputString Dump = OutputString();
+  // Skip over calling convention and attributes
+  Mangled = parseCallConvention(Call ? Call : &Dump, Mangled);
+  Mangled = parseAttributes(Attr ? Attr : &Dump, Mangled);
+
+  if (Args)
+    Args->append("(");
+
+  Mangled = parseFunctionArgs(Args ? Args : &Dump, Mangled);
+  if (Args)
+    Args->append(")");
+
+  Dump.free();
+  return Mangled;
+}
+
+const char *Demangler::parseFunctionType(OutputString *Decl,
+                                         const char *Mangled) {
+  OutputString Attr, Args, Type;
+
+  if (Mangled == nullptr || *Mangled == '\0')
+    return nullptr;
+
+  /* The order of the mangled string is:
+        CallConvention FuncAttrs Arguments ArgClose Type
+     The demangled string is re-ordered as:
+        CallConvention Type Arguments FuncAttrs
+   */
+  Attr = OutputString();
+  Args = OutputString();
+  Type = OutputString();
+
+  Mangled = parseFunctionTypeNoreturn(&Args, Decl, &Attr, Mangled);
+
+  // Function return type
+  Mangled = parseType(&Type, Mangled);
+
+  // Append to decl in order
+  Decl->append(Type.Buffer, Type.getLength());
+  Decl->append(Args.Buffer, Args.getLength());
+  Decl->append(" ");
+  Decl->append(Attr.Buffer, Attr.getLength());
+
+  Attr.free();
+  Args.free();
+  Type.free();
+  return Mangled;
+}
+
+const char *Demangler::parseFunctionArgs(OutputString *Decl,
+                                         const char *Mangled) {
+  size_t N = 0;
+
+  while (Mangled && *Mangled != '\0') {
+    switch (*Mangled) {
+    case 'X': /* (variadic T t...) style */
+      Mangled++;
+      Decl->append("...");
+      return Mangled;
+    case 'Y': /* (variadic T t, ...) style */
+      Mangled++;
+      if (N != 0)
+        Decl->append(", ");
+      Decl->append("...");
+      return Mangled;
+    case 'Z': /* Normal function */
+      Mangled++;
+      return Mangled;
+    }
+
+    if (N++)
+      Decl->append(", ");
+
+    if (*Mangled == 'M') /* scope(T) */
+    {
+      Mangled++;
+      Decl->append("scope ");
+    }
+
+    if (Mangled[0] == 'N' && Mangled[1] == 'k') /* return(T) */
+    {
+      Mangled += 2;
+      Decl->append("return ");
+    }
+
+    switch (*Mangled) {
+    case 'I': /* in(T) */
+      Mangled++;
+      Decl->append("in ");
+      if (*Mangled == 'K') /* in ref(T) */
+      {
+        Mangled++;
+        Decl->append("ref ");
+      }
+      break;
+    case 'J': /* out(T) */
+      Mangled++;
+      Decl->append("out ");
+      break;
+    case 'K': /* ref(T) */
+      Mangled++;
+      Decl->append("ref ");
+      break;
+    case 'L': /* lazy(T) */
+      Mangled++;
+      Decl->append("lazy ");
+      break;
+    }
+    Mangled = parseType(Decl, Mangled);
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseType(OutputString *Decl, const char *Mangled) {
+  if (Mangled == nullptr || *Mangled == '\0')
+    return nullptr;
+
+  switch (*Mangled) {
+  case 'O': /* shared(T) */
+    Mangled++;
+    Decl->append("shared(");
+    Mangled = parseType(Decl, Mangled);
+    Decl->append(")");
+    return Mangled;
+
+  case 'x': /* const(T) */
+    Mangled++;
+    Decl->append("const(");
+    Mangled = parseType(Decl, Mangled);
+    Decl->append(")");
+    return Mangled;
+
+  case 'y': /* immutable(T) */
+    Mangled++;
+    Decl->append("immutable(");
+    Mangled = parseType(Decl, Mangled);
+    Decl->append(")");
+    return Mangled;
+
+  case 'N':
+    Mangled++;
+
+    switch (*Mangled) {
+    case 'g': // wild(T)
+      Mangled++;
+      Decl->append("inout(");
+      Mangled = parseType(Decl, Mangled);
+      Decl->append(")");
+      return Mangled;
+
+    case 'h': // vector(T)
+      Mangled++;
+      Decl->append("__vector(");
+      Mangled = parseType(Decl, Mangled);
+      Decl->append(")");
+      return Mangled;
+
+    case 'n': // typeof(*null)
+      Mangled++;
+      Decl->append("typeof(*null)");
+      return Mangled;
+    }
+
+    // invalid
+    return nullptr;
+
+  case 'A': /* dynamic array (T[]) */
+    Mangled++;
+    Mangled = parseType(Decl, Mangled);
+    Decl->append("[]");
+    return Mangled;
+
+  case 'G': /* static array (T[N]) */
+  {
+    const char *NumPtr;
+    size_t Num = 0;
+    Mangled++;
+
+    NumPtr = Mangled;
+    while (std::isdigit(*Mangled)) {
+      Num++;
+      Mangled++;
+    }
+    Mangled = parseType(Decl, Mangled);
+    Decl->append("[");
+    Decl->append(NumPtr, Num);
+    Decl->append("]");
+    return Mangled;
+  }
+
+  case 'H': /* associative array (T[T]) */
+  {
+    OutputString Type = OutputString();
+    size_t Sztype;
+    Mangled++;
+
+    Mangled = parseType(&Type, Mangled);
+    Sztype = Type.getLength();
+
+    Mangled = parseType(Decl, Mangled);
+    Decl->append("[");
+    Decl->append(Type.Buffer, Sztype);
+    Decl->append("]");
+
+    Type.free();
+    return Mangled;
+  }
+
+  case 'P': /* pointer (T*) */
+    Mangled++;
+    if (!isCallConvention(Mangled)) {
+      Mangled = parseType(Decl, Mangled);
+      Decl->append("*");
+      return Mangled;
+    }
+
+    [[clang::fallthrough]];
+  case 'F': /* function T (D) */
+  case 'U': /* function T (C) */
+  case 'W': /* function T (Windows) */
+  case 'V': /* function T (Pascal) */
+  case 'R': /* function T (C++) */
+  case 'Y': /* function T (Objective-C) */
+    /* Function pointer types don't include the trailing asterisk.  */
+    Mangled = parseFunctionType(Decl, Mangled);
+    Decl->append("function");
+    return Mangled;
+
+  case 'C': /* class T */
+  case 'S': /* struct T */
+  case 'E': /* enum T */
+  case 'T': /* typedef T */
+    Mangled++;
+    return parseQualified(Decl, Mangled, false);
+
+  case 'D': /* delegate T */
+  {
+    OutputString Mods = OutputString();
+    size_t Szmods;
+    Mangled++;
+
+    Mangled = parseTypeModifiers(&Mods, Mangled);
+    Szmods = Mods.getLength();
+
+    // Back referenced function type
+    if (Mangled && *Mangled == 'Q')
+      Mangled = parseTypeBackref(Decl, Mangled, true);
+    else
+      Mangled = parseFunctionType(Decl, Mangled);
+
+    Decl->append("delegate");
+    Decl->append(Mods.Buffer, Szmods);
+
+    Mods.free();
+    return Mangled;
+  }
+
+  case 'B': /* tuple T */
+    Mangled++;
+    return parseTuple(Decl, Mangled);
+
+  /* Basic types */
+  case 'n':
+    Mangled++;
+    Decl->append("typeof(null)");
+    return Mangled;
+
+  case 'v':
+    Mangled++;
+    Decl->append("void");
+    return Mangled;
+
+  case 'g':
+    Mangled++;
+    Decl->append("byte");
+    return Mangled;
+  case 'h':
+    Mangled++;
+    Decl->append("ubyte");
+    return Mangled;
+
+  case 's':
+    Mangled++;
+    Decl->append("short");
+    return Mangled;
+  case 't':
+    Mangled++;
+    Decl->append("ushort");
+    return Mangled;
+
+  case 'i':
+    Mangled++;
+    Decl->append("int");
+    return Mangled;
+  case 'k':
+    Mangled++;
+    Decl->append("uint");
+    return Mangled;
+
+  case 'l':
+    Mangled++;
+    Decl->append("long");
+    return Mangled;
+  case 'm':
+    Mangled++;
+    Decl->append("ulong");
+    return Mangled;
+
+  case 'f':
+    Mangled++;
+    Decl->append("float");
+    return Mangled;
+  case 'd':
+    Mangled++;
+    Decl->append("double");
+    return Mangled;
+  case 'e':
+    Mangled++;
+    Decl->append("real");
+    return Mangled;
+
+  // Imaginary types
+  case 'o':
+    Mangled++;
+    Decl->append("ifloat");
+    return Mangled;
+  case 'p':
+    Mangled++;
+    Decl->append("idouble");
+    return Mangled;
+  case 'j':
+    Mangled++;
+    Decl->append("ireal");
+    return Mangled;
+
+  // Complex types
+  case 'q':
+    Mangled++;
+    Decl->append("cfloat");
+    return Mangled;
+  case 'r':
+    Mangled++;
+    Decl->append("cdouble");
+    return Mangled;
+  case 'c':
+    Mangled++;
+    Decl->append("creal");
+    return Mangled;
+
+  // Other types
+  case 'b':
+    Mangled++;
+    Decl->append("bool");
+    return Mangled;
+
+  case 'a':
+    Mangled++;
+    Decl->append("char");
+    return Mangled;
+  case 'u':
+    Mangled++;
+    Decl->append("wchar");
+    return Mangled;
+  case 'w':
+    Mangled++;
+    Decl->append("dchar");
+    return Mangled;
+
+  case 'z':
+    Mangled++;
+
+    switch (*Mangled) {
+    case 'i':
+      Mangled++;
+      Decl->append("cent");
+      return Mangled;
+    case 'k':
+      Mangled++;
+      Decl->append("ucent");
+      return Mangled;
+    }
+    return nullptr;
+
+  // Back referenced type
+  case 'Q':
+    return parseTypeBackref(Decl, Mangled, false);
+
+  default: // unhandled
+    return nullptr;
+  }
+}
+
+const char *Demangler::parseIdentifier(OutputString *Decl,
+                                       const char *Mangled) {
+  unsigned long Len;
+
+  if (Mangled == nullptr || *Mangled == '\0')
+    return nullptr;
+
+  if (*Mangled == 'Q')
+    return parseSymbolBackref(Decl, Mangled);
+
+  /* May be a template instance without a length prefix.  */
+  if (Mangled[0] == '_' && Mangled[1] == '_' &&
+      (Mangled[2] == 'T' || Mangled[2] == 'U'))
+    return parseTemplate(Decl, Mangled);
+
+  const char *Endptr = decodeNumber(Mangled, &Len);
+
+  if (Endptr == nullptr || Len == 0)
+    return nullptr;
+
+  if (strlen(Endptr) < Len)
+    return nullptr;
+
+  Mangled = Endptr;
+
+  /* May be a template instance with a length prefix.  */
+  if (Len >= 5 && Mangled[0] == '_' && Mangled[1] == '_' &&
+      (Mangled[2] == 'T' || Mangled[2] == 'U'))
+    return parseTemplate(Decl, Mangled, Len);
+
+  /* There can be multiple different declarations in the same function that have
+     the same mangled name.  To make the mangled names unique, a fake parent in
+     the form `__Sddd' is added to the symbol.  */
+  if (Len >= 4 && Mangled[0] == '_' && Mangled[1] == '_' && Mangled[2] == 'S') {
+    const char *NumPtr = Mangled + 3;
+    while (NumPtr < (Mangled + Len) && std::isdigit(*NumPtr))
+      NumPtr++;
+
+    if (Mangled + Len == NumPtr) {
+      /* Skip over the fake parent.  */
+      Mangled += Len;
+      return parseIdentifier(Decl, Mangled);
+    }
+
+    /* else demangle it as a plain identifier.  */
+  }
+
+  return parseLName(Decl, Mangled, Len);
+}
+
+const char *Demangler::parseLName(OutputString *Decl, const char *Mangled,
+                                  unsigned long Len) {
+  switch (Len) {
+  case 6:
+    if (strncmp(Mangled, "__ctor", Len) == 0) {
+      /* Constructor symbol for a class/struct.  */
+      Decl->append("this");
+      Mangled += Len;
+      return Mangled;
+    } else if (strncmp(Mangled, "__dtor", Len) == 0) {
+      /* Destructor symbol for a class/struct.  */
+      Decl->append("~this");
+      Mangled += Len;
+      return Mangled;
+    } else if (strncmp(Mangled, "__initZ", Len + 1) == 0) {
+      /* The static initialiser for a given symbol.  */
+      Decl->prepend("initializer for ");
+      Decl->setLength(Decl->getLength() - 1);
+      Mangled += Len;
+      return Mangled;
+    } else if (strncmp(Mangled, "__vtblZ", Len + 1) == 0) {
+      /* The vtable symbol for a given class.  */
+      Decl->prepend("vtable for ");
+      Decl->setLength(Decl->getLength() - 1);
+      Mangled += Len;
+      return Mangled;
+    }
+    break;
+
+  case 7:
+    if (strncmp(Mangled, "__ClassZ", Len + 1) == 0) {
+      /* The classinfo symbol for a given class.  */
+      Decl->prepend("ClassInfo for ");
+      Decl->setLength(Decl->getLength() - 1);
+      Mangled += Len;
+      return Mangled;
+    }
+    break;
+
+  case 10:
+    if (strncmp(Mangled, "__postblitMFZ", Len + 3) == 0) {
+      /* Postblit symbol for a struct.  */
+      Decl->append("this(this)");
+      Mangled += Len + 3;
+      return Mangled;
+    }
+    break;
+
+  case 11:
+    if (strncmp(Mangled, "__InterfaceZ", Len + 1) == 0) {
+      /* The interface symbol for a given class.  */
+      Decl->prepend("Interface for ");
+      Decl->setLength(Decl->getLength() - 1);
+      Mangled += Len;
+      return Mangled;
+    }
+    break;
+
+  case 12:
+    if (strncmp(Mangled, "__ModuleInfoZ", Len + 1) == 0) {
+      /* The ModuleInfo symbol for a given module.  */
+      Decl->prepend("ModuleInfo for ");
+      Decl->setLength(Decl->getLength() - 1);
+      Mangled += Len;
+      return Mangled;
+    }
+    break;
+  }
+
+  Decl->append(Mangled, Len);
+  Mangled += Len;
+
+  return Mangled;
+}
+
+const char *Demangler::parseInteger(OutputString *Decl, const char *Mangled,
+                                    char Type) {
+  if (Type == 'a' || Type == 'u' || Type == 'w') {
+    /* Parse character value.  */
+    char Value[20];
+    int Pos = sizeof(Value);
+    int Width = 0;
+    unsigned long Val;
+
+    Mangled = decodeNumber(Mangled, &Val);
+    if (Mangled == nullptr)
+      return nullptr;
+
+    Decl->append('\'');
+
+    if (Type == 'a' && Val >= 0x20 && Val < 0x7F) {
+      /* Represent as a character literal.  */
+      Decl->append(static_cast<char>(Val));
+    } else {
+      /* Represent as a hexadecimal value. */
+      switch (Type) {
+      case 'a': /* char */
+        Decl->append("\\x");
+        Width = 2;
+        break;
+      case 'u': /* wchar */
+        Decl->append("\\u");
+        Width = 4;
+        break;
+      case 'w': /* dchar */
+        Decl->append("\\U");
+        Width = 8;
+        break;
+      }
+
+      while (Val > 0) {
+        int Digit = Val % 16;
+
+        if (Digit < 10)
+          Value[--Pos] = (char)(Digit + '0');
+        else
+          Value[--Pos] = (char)((Digit - 10) + 'a');
+
+        Val /= 16;
+        Width--;
+      }
+
+      for (; Width > 0; Width--)
+        Value[--Pos] = '0';
+
+      Decl->append(&(Value[Pos]), sizeof(Value) - Pos);
+    }
+    Decl->append('\'');
+  } else if (Type == 'b') {
+    /* Parse boolean value.  */
+    unsigned long Val;
+
+    Mangled = decodeNumber(Mangled, &Val);
+    if (Mangled == nullptr)
+      return nullptr;
+
+    Decl->append(Val ? "true" : "false");
+  } else {
+    /* Parse integer value.  */
+    const char *NumPtr = Mangled;
+    size_t Num = 0;
+
+    if (!std::isdigit(*Mangled))
+      return nullptr;
+
+    while (std::isdigit(*Mangled)) {
+      Num++;
+      Mangled++;
+    }
+    Decl->append(NumPtr, Num);
+
+    /* Append suffix.  */
+    switch (Type) {
+    case 'h': /* ubyte */
+    case 't': /* ushort */
+    case 'k': /* uint */
+      Decl->append('u');
+      break;
+    case 'l': /* long */
+      Decl->append('L');
+      break;
+    case 'm': /* ulong */
+      Decl->append("uL");
+      break;
+    }
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseReal(OutputString *Decl, const char *Mangled) {
+  // Handle NAN and +-INF
+  if (strncmp(Mangled, "NAN", 3) == 0) {
+    Decl->append("NaN");
+    Mangled += 3;
+    return Mangled;
+  }
+
+  if (strncmp(Mangled, "INF", 3) == 0) {
+    Decl->append("Inf");
+    Mangled += 3;
+    return Mangled;
+  }
+
+  if (strncmp(Mangled, "NINF", 4) == 0) {
+    Decl->append("-Inf");
+    Mangled += 4;
+    return Mangled;
+  }
+
+  // Hexadecimal prefix and leading bit
+  if (*Mangled == 'N') {
+    Decl->append('-');
+    Mangled++;
+  }
+
+  if (!std::isxdigit(*Mangled))
+    return nullptr;
+
+  Decl->append("0x");
+  Decl->append(Mangled, 1);
+  Decl->append('.');
+  Mangled++;
+
+  // Significand
+  while (std::isxdigit(*Mangled)) {
+    Decl->append(Mangled, 1);
+    Mangled++;
+  }
+
+  // Exponent
+  if (*Mangled != 'P')
+    return nullptr;
+
+  Decl->append('p');
+  Mangled++;
+
+  if (*Mangled == 'N') {
+    Decl->append('-');
+    Mangled++;
+  }
+
+  while (std::isdigit(*Mangled)) {
+    Decl->append(Mangled, 1);
+    Mangled++;
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseString(OutputString *Decl, const char *Mangled) {
+  char Type = *Mangled;
+  unsigned long Len;
+
+  Mangled++;
+  Mangled = decodeNumber(Mangled, &Len);
+  if (Mangled == nullptr || *Mangled != '_')
+    return nullptr;
+
+  Mangled++;
+  Decl->append('\"');
+  while (Len--) {
+    char Val;
+    const char *Endptr = decodeHexdigit(Mangled, &Val);
+
+    if (Endptr == nullptr)
+      return nullptr;
+
+    /* Sanitize white and non-printable characters.  */
+    switch (Val) {
+    case ' ':
+      Decl->append(' ');
+      break;
+    case '\t':
+      Decl->append("\\t");
+      break;
+    case '\n':
+      Decl->append("\\n");
+      break;
+    case '\r':
+      Decl->append("\\r");
+      break;
+    case '\f':
+      Decl->append("\\f");
+      break;
+    case '\v':
+      Decl->append("\\v");
+      break;
+
+    default:
+      if (std::isprint(Val))
+        Decl->append(Val);
+      else {
+        Decl->append("\\x");
+        Decl->append(Mangled, 2);
+      }
+    }
+
+    Mangled = Endptr;
+  }
+  Decl->append('\"');
+
+  if (Type != 'a')
+    Decl->append(Type);
+
+  return Mangled;
+}
+
+const char *Demangler::parseArrayLiteral(OutputString *Decl,
+                                         const char *Mangled) {
+  unsigned long Elements;
+
+  Mangled = decodeNumber(Mangled, &Elements);
+  if (Mangled == nullptr)
+    return nullptr;
+
+  Decl->append('[');
+  while (Elements--) {
+    Mangled = parseValue(Decl, Mangled, nullptr, '\0');
+    if (Mangled == nullptr)
+      return nullptr;
+
+    if (Elements != 0)
+      Decl->append(", ");
+  }
+
+  Decl->append(']');
+  return Mangled;
+}
+
+const char *Demangler::parseAssocArray(OutputString *Decl,
+                                       const char *Mangled) {
+  unsigned long Elements;
+
+  Mangled = decodeNumber(Mangled, &Elements);
+  if (Mangled == nullptr)
+    return nullptr;
+
+  Decl->append('[');
+  while (Elements--) {
+    Mangled = parseValue(Decl, Mangled, nullptr, '\0');
+    if (Mangled == nullptr)
+      return nullptr;
+
+    Decl->append(':');
+    Mangled = parseValue(Decl, Mangled, nullptr, '\0');
+    if (Mangled == nullptr)
+      return nullptr;
+
+    if (Elements != 0)
+      Decl->append(", ");
+  }
+
+  Decl->append(']');
+  return Mangled;
+}
+
+const char *Demangler::parseStructLiteral(OutputString *Decl,
+                                          const char *Mangled,
+                                          const char *Name) {
+  unsigned long Args;
+
+  Mangled = decodeNumber(Mangled, &Args);
+  if (Mangled == nullptr)
+    return nullptr;
+
+  if (Name != nullptr)
+    Decl->append(Name);
+
+  Decl->append('(');
+  while (Args--) {
+    Mangled = parseValue(Decl, Mangled, nullptr, '\0');
+    if (Mangled == nullptr)
+      return nullptr;
+
+    if (Args != 0)
+      Decl->append(", ");
+  }
+
+  Decl->append(')');
+  return Mangled;
+}
+
+const char *Demangler::parseValue(OutputString *Decl, const char *Mangled,
+                                  const char *Name, char Type) {
+  if (Mangled == nullptr || *Mangled == '\0')
+    return nullptr;
+
+  switch (*Mangled) {
+    /* Null value.  */
+  case 'n':
+    Mangled++;
+    Decl->append("null");
+    break;
+
+    /* Integral values.  */
+  case 'N':
+    Mangled++;
+    Decl->append('-');
+    Mangled = parseInteger(Decl, Mangled, Type);
+    break;
+
+  case 'i':
+    Mangled++;
+    /* Fall through */
+
+    /* There really should always be an `i' before encoded numbers, but there
+       wasn't in early versions of D2, so this case range must remain for
+       backwards compatibility.  */
+    [[clang::fallthrough]];
+  case '0':
+  case '1':
+  case '2':
+  case '3':
+  case '4':
+  case '5':
+  case '6':
+  case '7':
+  case '8':
+  case '9':
+    Mangled = parseInteger(Decl, Mangled, Type);
+    break;
+
+    /* Real value.  */
+  case 'e':
+    Mangled++;
+    Mangled = parseReal(Decl, Mangled);
+    break;
+
+    /* Complex value.  */
+  case 'c':
+    Mangled++;
+    Mangled = parseReal(Decl, Mangled);
+    Decl->append('+');
+    if (Mangled == nullptr || *Mangled != 'c')
+      return nullptr;
+    Mangled++;
+    Mangled = parseReal(Decl, Mangled);
+    Decl->append('i');
+    break;
+
+    /* String values.  */
+  case 'a': /* UTF8 */
+  case 'w': /* UTF16 */
+  case 'd': /* UTF32 */
+    Mangled = parseString(Decl, Mangled);
+    break;
+
+    /* Array values.  */
+  case 'A':
+    Mangled++;
+    if (Type == 'H')
+      Mangled = parseAssocArray(Decl, Mangled);
+    else
+      Mangled = parseArrayLiteral(Decl, Mangled);
+    break;
+
+    /* Struct values.  */
+  case 'S':
+    Mangled++;
+    Mangled = parseStructLiteral(Decl, Mangled, Name);
+    break;
+
+    /* Function literal symbol.  */
+  case 'f':
+    Mangled++;
+    if (strncmp(Mangled, "_D", 2) != 0 || !isSymbolName(Mangled + 2))
+      return nullptr;
+    Mangled = parseMangle(Decl, Mangled);
+    break;
+
+  default:
+    return nullptr;
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseMangle(OutputString *Decl, const char *Mangled) {
+  /* A D mangled symbol is comprised of both scope and type information.
+        MangleName:
+            _D QualifiedName Type
+            _D QualifiedName Z
+            ^
+     The caller should have guaranteed that the start pointer is at the
+     above location.
+     Note that type is never a function type, but only the return type of
+     a function or the type of a variable.
+   */
+  Mangled += 2;
+
+  Mangled = parseQualified(Decl, Mangled, true);
+
+  if (Mangled != nullptr) {
+    /* Artificial symbols end with 'Z' and have no type.  */
+    if (*Mangled == 'Z')
+      Mangled++;
+    else {
+      /* Discard the declaration or return type.  */
+      OutputString Type = OutputString();
+
+      Mangled = parseType(&Type, Mangled);
+      Type.free();
+    }
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseQualified(OutputString *Decl, const char *Mangled,
+                                      bool SuffixModifiers) {
+  /* Qualified names are identifiers separated by their encoded length.
+     Nested functions also encode their argument types without specifying
+     what they return.
+        QualifiedName:
+            SymbolFunctionName
+            SymbolFunctionName QualifiedName
+            ^
+        SymbolFunctionName:
+            SymbolName
+            SymbolName TypeFunctionNoReturn
+            SymbolName M TypeFunctionNoReturn
+            SymbolName M TypeModifiers TypeFunctionNoReturn
+     The start pointer should be at the above location.
+   */
+  size_t N = 0;
+  do {
+    if (N++)
+      Decl->append('.');
+
+    /* Skip over anonymous symbols.  */
+    while (*Mangled == '0')
+      Mangled++;
+
+    Mangled = parseIdentifier(Decl, Mangled);
+
+    /* Consume the encoded arguments.  However if this is not followed by the
+       next encoded length or mangle type, then this is not a continuation of
+       a qualified name, in which case we backtrack and return the current
+       unconsumed position of the mangled decl.  */
+    if (Mangled && (*Mangled == 'M' || isCallConvention(Mangled))) {
+      const char *Start = Mangled;
+      int Saved = Decl->getLength();
+
+      /* Save the type modifiers for appending at the end if needed. */
+      OutputString Mods = OutputString();
+
+      /* Skip over 'this' parameter and type modifiers.  */
+      if (*Mangled == 'M') {
+        Mangled++;
+        Mangled = parseTypeModifiers(&Mods, Mangled);
+        Decl->setLength(Saved);
+      }
+
+      Mangled = parseFunctionTypeNoreturn(Decl, nullptr, nullptr, Mangled);
+      if (SuffixModifiers)
+        Decl->append(Mods.Buffer, Mods.getLength());
+
+      if (Mangled == nullptr || *Mangled == '\0') {
+        /* Did not match the rule we were looking for.  */
+        Mangled = Start;
+        Decl->setLength(Saved);
+      }
+
+      Mods.free();
+    }
+  } while (Mangled && isSymbolName(Mangled));
+
+  return Mangled;
+}
+
+const char *Demangler::parseTuple(OutputString *Decl, const char *Mangled) {
+  unsigned long Elements;
+
+  Mangled = decodeNumber(Mangled, &Elements);
+  if (Mangled == nullptr)
+    return nullptr;
+
+  Decl->append("Tuple!(");
+
+  while (Elements--) {
+    Mangled = parseType(Decl, Mangled);
+    if (Mangled == nullptr)
+      return nullptr;
+
+    if (Elements != 0)
+      Decl->append(", ");
+  }
+
+  Decl->append(')');
+  return Mangled;
+}
+
+const char *Demangler::parseTemplateSymbolParameter(OutputString *Decl,
+                                                    const char *Mangled) {
+  if (strncmp(Mangled, "_D", 2) == 0 && isSymbolName(Mangled + 2))
+    return parseMangle(Decl, Mangled);
+
+  if (*Mangled == 'Q')
+    return parseQualified(Decl, Mangled, false);
+
+  unsigned long Len;
+  const char *EndPtr = decodeNumber(Mangled, &Len);
+
+  if (EndPtr == nullptr || Len == 0)
+    return nullptr;
+
+  /* In template parameter symbols generated by the frontend up to 2.076,
+     the symbol length is encoded and the first character of the mangled
+     name can be a digit.  This causes ambiguity issues because the digits
+     of the two numbers are adjacent.  */
+  long PtrSize = Len;
+  const char *PtrEnd;
+  int Saved = Decl->getLength();
+
+  /* Work backwards until a match is found.  */
+  for (PtrEnd = EndPtr; EndPtr != nullptr; PtrEnd--) {
+    Mangled = PtrEnd;
+
+    /* Reached the beginning of the pointer to the name length,
+       try parsing the entire symbol.  */
+    if (PtrSize == 0) {
+      PtrSize = Len;
+      PtrEnd = EndPtr;
+      EndPtr = nullptr;
+    }
+
+    /* Check whether template parameter is a function with a valid
+       return type or an untyped identifier.  */
+    if (isSymbolName(Mangled))
+      Mangled = parseQualified(Decl, Mangled, false);
+    else if (strncmp(Mangled, "_D", 2) == 0 && isSymbolName(Mangled + 2))
+      Mangled = parseMangle(Decl, Mangled);
+
+    /* Check for name length mismatch.  */
+    if (Mangled && (EndPtr == nullptr || (Mangled - PtrEnd) == PtrSize))
+      return Mangled;
+
+    PtrSize /= 10;
+    Decl->setLength(Saved);
+  }
+
+  /* No match on any combinations.  */
+  return nullptr;
+}
+
+const char *Demangler::parseTemplateArgs(OutputString *Decl,
+                                         const char *Mangled) {
+  size_t N = 0;
+
+  while (Mangled && *Mangled != '\0') {
+    switch (*Mangled) {
+    case 'Z': /* End of parameter list.  */
+      Mangled++;
+      return Mangled;
+    }
+
+    if (N++)
+      Decl->append(", ");
+
+    /* Skip over specialised template prefix.  */
+    if (*Mangled == 'H')
+      Mangled++;
+
+    switch (*Mangled) {
+    case 'S': /* Symbol parameter.  */
+      Mangled++;
+      Mangled = parseTemplateSymbolParameter(Decl, Mangled);
+      break;
+    case 'T': /* Type parameter.  */
+      Mangled++;
+      Mangled = parseType(Decl, Mangled);
+      break;
+    case 'V': /* Value parameter. */
+    {
+      OutputString Name;
+      char Type;
+
+      /* Peek at the type.  */
+      Mangled++;
+      Type = *Mangled;
+
+      if (Type == 'Q') {
+        /* Value type is a back reference, peek at the real type.  */
+        const char *Backref;
+        if (decodeBackref(Mangled, &Backref) == nullptr)
+          return nullptr;
+
+        Type = *Backref;
+      }
+
+      /* In the few instances where the type is actually desired in
+         the output, it should precede the value from dlang_value.  */
+      Name = OutputString();
+      Mangled = parseType(&Name, Mangled);
+      Name.append('\0');
+      Name.Ptr--;
+
+      Mangled = parseValue(Decl, Mangled, Name.Buffer, Type);
+      Name.free();
+      break;
+    }
+    case 'X': /* Externally mangled parameter.  */
+    {
+      unsigned long Len;
+      const char *EndPtr;
+
+      Mangled++;
+      EndPtr = decodeNumber(Mangled, &Len);
+      if (EndPtr == nullptr || strlen(EndPtr) < Len)
+        return nullptr;
+
+      Decl->append(EndPtr, Len);
+      Mangled = EndPtr + Len;
+      break;
+    }
+    default:
+      return nullptr;
+    }
+  }
+
+  return Mangled;
+}
+
+const char *Demangler::parseTemplate(OutputString *Decl, const char *Mangled,
+                                     unsigned long Len) {
+  const char *Start = Mangled;
+  OutputString Args;
+
+  /* Template instance names have the types and values of its parameters
+     encoded into it.
+        TemplateInstanceName:
+            Number __T LName TemplateArgs Z
+            Number __U LName TemplateArgs Z
+                   ^
+     The start pointer should be at the above location, and LEN should be
+     the value of the decoded number.
+   */
+
+  /* Template symbol. */
+  if (!isSymbolName(Mangled + 3) || Mangled[3] == '0')
+    return nullptr;
+
+  Mangled += 3;
+
+  /* Template identifier. */
+  Mangled = parseIdentifier(Decl, Mangled);
+
+  /* Template arguments. */
+  Args = OutputString();
+  Mangled = parseTemplateArgs(&Args, Mangled);
+
+  Decl->append("!(");
+  Decl->append(Args.Buffer, Args.getLength());
+  Decl->append(')');
+
+  Args.free();
+
+  /* Check for template name length mismatch.  */
+  if (Len != -1UL && Mangled && (unsigned long)(Mangled - Start) != Len)
+    return nullptr;
+
+  return Mangled;
+}
+
+Demangler::Demangler(const char *Mangled)
+    : Str(Mangled), LastBackref(strlen(Mangled)) {}
+
+const char *Demangler::parseMangle(OutputString *Decl) {
+  return parseMangle(Decl, this->Str);
+}
+
+char *llvm::dlangDemangle(const char *MangledName) {
+  OutputString Decl;
+  char *Demangled = nullptr;
+
+  if (MangledName == nullptr || *MangledName == '\0')
+    return nullptr;
+
+  if (strncmp(MangledName, "_D", 2) != 0)
+    return nullptr;
+
+  Decl = OutputString();
+
+  if (strcmp(MangledName, "_Dmain") == 0) {
+    Decl.append("D main");
+  } else {
+
+    Demangler D = Demangler(MangledName);
+    MangledName = D.parseMangle(&Decl);
+
+    /* Check that the entire symbol was successfully demangled.  */
+    if (MangledName == nullptr || *MangledName != '\0')
+      Decl.free();
+  }
+
+  if (Decl.getLength() > 0) {
+    Decl.append('\0');
+    Decl.Ptr--;
+    Demangled = Decl.Buffer;
+  }
+
+  return Demangled;
+}
+
+/* vim: set ts=2 sw=2 expandtab */

llvm/lib/Demangle/Demangle.cpp

          MangledName[1] == 'R';
 }
 
+static bool isDLangEncoding(const std::string &MangledName) {
+  return MangledName.size() >= 2 && MangledName[0] == '_' &&
+         MangledName[1] == 'D';
+}
+
 std::string llvm::demangle(const std::string &MangledName) {
   char *Demangled;
   if (isItaniumEncoding(MangledName))
     Demangled = itaniumDemangle(MangledName.c_str(), nullptr, nullptr, nullptr);
   else if (isRustEncoding(MangledName))
     Demangled = rustDemangle(MangledName.c_str(), nullptr, nullptr, nullptr);
+  else if (isDLangEncoding(MangledName))
+    Demangled = dlangDemangle(MangledName.c_str());
   else
     Demangled = microsoftDemangle(MangledName.c_str(), nullptr, nullptr,
                                   nullptr, nullptr);

llvm/tools/llvm-dlang-demangle-fuzzer/CMakeLists.txt

+set(LLVM_LINK_COMPONENTS
+  Demangle
+  FuzzMutate
+  Support
+)
+
+add_llvm_fuzzer(llvm-dlang-demangle-fuzzer
+  llvm-dlang-demangle-fuzzer.cpp
+  DUMMY_MAIN DummyDemanglerFuzzer.cpp
+  )

llvm/tools/llvm-dlang-demangle-fuzzer/DummyDemanglerFuzzer.cpp

+//===-- DummyDemanglerFuzzer.cpp - Entry point to sanity check the fuzzer -===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation of main so we can build and test without linking libFuzzer.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/FuzzMutate/FuzzerCLI.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
+int main(int argc, char *argv[]) {
+  return llvm::runFuzzerOnInputs(argc, argv, LLVMFuzzerTestOneInput);
+}

llvm/tools/llvm-dlang-demangle-fuzzer/llvm-dlang-demangle-fuzzer.cpp

+//===--- llvm-dlang-demangle-fuzzer.cpp - Fuzzer for the DLang Demangler --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Demangle/Demangle.h"
+#include <cstdint>
+#include <cstdlib>
+#include <string>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  std::string NullTerminatedString((const char *)Data, Size);
+  char *Demangled = llvm::dlangDemangle(NullTerminatedString.c_str());
+  std::free(Demangled);
+  return 0;
+}

llvm/unittests/Demangle/CMakeLists.txt

 
 add_llvm_unittest(DemangleTests
   DemangleTest.cpp
+  DLangDemangleTest.cpp
   ItaniumDemangleTest.cpp
   PartialDemangleTest.cpp
   RustDemangleTest.cpp

llvm/unittests/Demangle/DLangDemangleTest.cpp

+//===------------------ DLangDemangleTest.cpp -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Testing input ported from libiberty library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Demangle/Demangle.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+#include <cstdlib>
+
+TEST(DLangDemangle, Success) {
+  struct ExpectedVal {
+    const char *Mangled;
+    const char *Expected;
+  };
+
+  ExpectedVal ExpectedArray[] = {
+      {"_Dmain", "D main"},
+      {"_D3app4mainFZ6dg_fooMFZi", "app.main().dg_foo()"},
+      {"_D3app6foobarFPiAiHiieSQv3FooSQBc3BarZi",
+       "app.foobar(int*, int[], int[int], real, app.Foo, app.Bar)"},
+      {"_D8demangle4testPFLAiYi", "demangle.test"},
+      {"_D8demangle4testFZv", "demangle.test()"},
+      {"_D8demangle4testMFZ2fnMFZv", "demangle.test().fn()"},
+      {"_D8demangle4testFaZv", "demangle.test(char)"},
+      {"_D8demangle4testFbZv", "demangle.test(bool)"},
+      {"_D8demangle4testFcZv", "demangle.test(creal)"},
+      {"_D8demangle4testFdZv", "demangle.test(double)"},
+      {"_D8demangle4testFeZv", "demangle.test(real)"},
+      {"_D8demangle4testFfZv", "demangle.test(float)"},
+      {"_D8demangle4testFgZv", "demangle.test(byte)"},
+      {"_D8demangle4testFhZv", "demangle.test(ubyte)"},
+      {"_D8demangle4testFiZv", "demangle.test(int)"},
+      {"_D8demangle4testFjZv", "demangle.test(ireal)"},
+      {"_D8demangle4testFkZv", "demangle.test(uint)"},
+      {"_D8demangle4testFlZv", "demangle.test(long)"},
+      {"_D8demangle4testFmZv", "demangle.test(ulong)"},
+      {"_D8demangle4testFnZv", "demangle.test(typeof(null))"},
+      {"_D8demangle4testFNnZv", "demangle.test(typeof(*null))"},
+      {"_D8demangle4testFoZv", "demangle.test(ifloat)"},
+      {"_D8demangle4testFpZv", "demangle.test(idouble)"},
+      {"_D8demangle4testFqZv", "demangle.test(cfloat)"},
+      {"_D8demangle4testFrZv", "demangle.test(cdouble)"},
+      {"_D8demangle4testFsZv", "demangle.test(short)"},
+      {"_D8demangle4testFtZv", "demangle.test(ushort)"},
+      {"_D8demangle4testFuZv", "demangle.test(wchar)"},
+      {"_D8demangle4testFvZv", "demangle.test(void)"},
+      {"_D8demangle4testFwZv", "demangle.test(dchar)"},
+      {"_D8demangle4testFziZv", "demangle.test(cent)"},
+      {"_D8demangle4testFzkZv", "demangle.test(ucent)"},
+      {"_D8demangle4testFOaZv", "demangle.test(shared(char))"},
+      {"_D8demangle4testFxaZv", "demangle.test(const(char))"},
+      {"_D8demangle4testFyaZv", "demangle.test(immutable(char))"},
+      {"_D8demangle4testFNgaZv", "demangle.test(inout(char))"},
+      {"_D8demangle4testFOxaZv", "demangle.test(shared(const(char)))"},
+      {"_D8demangle4testFONgaZv", "demangle.test(shared(inout(char)))"},
+      {"_D8demangle4testFAaZv", "demangle.test(char[])"},
+      {"_D8demangle4testFAAaZv", "demangle.test(char[][])"},
+      {"_D8demangle4testFAAAaZv", "demangle.test(char[][][])"},
+      {"_D8demangle4testFG42aZv", "demangle.test(char[42])"},
+      {"_D8demangle4testFG42G42aZv", "demangle.test(char[42][42])"},
+      {"_D8demangle4testFG42G42G42aZv", "demangle.test(char[42][42][42])"},
+      {"_D8demangle4testFG1234567890aZv", "demangle.test(char[1234567890])"},
+      {"_D8demangle4testFHaaZv", "demangle.test(char[char])"},
+      {"_D8demangle4testFHHaaaZv", "demangle.test(char[char[char]])"},
+      {"_D8demangle4testFPaZv", "demangle.test(char*)"},
+      {"_D8demangle4testFPPaZv", "demangle.test(char**)"},
+      {"_D8demangle4testFPPPaZv", "demangle.test(char***)"},
+      {"_D8demangle4testFNhG8gZv", "demangle.test(__vector(byte[8]))"},
+      {"_D8demangle4testFNhG16gZv", "demangle.test(__vector(byte[16]))"},
+      {"_D8demangle4testFNhG32gZv", "demangle.test(__vector(byte[32]))"},
+      {"_D8demangle4testFNhG4sZv", "demangle.test(__vector(short[4]))"},
+      {"_D8demangle4testFNhG8sZv", "demangle.test(__vector(short[8]))"},
+      {"_D8demangle4testFNhG16sZv", "demangle.test(__vector(short[16]))"},
+      {"_D8demangle4testFNhG2iZv", "demangle.test(__vector(int[2]))"},
+      {"_D8demangle4testFNhG4iZv", "demangle.test(__vector(int[4]))"},
+      {"_D8demangle4testFNhG8iZv", "demangle.test(__vector(int[8]))"},
+      {"_D8demangle4testFNhG1lZv", "demangle.test(__vector(long[1]))"},
+      {"_D8demangle4testFNhG2lZv", "demangle.test(__vector(long[2]))"},
+      {"_D8demangle4testFNhG4lZv", "demangle.test(__vector(long[4]))"},
+      {"_D8demangle4testFNhG2fZv", "demangle.test(__vector(float[2]))"},
+      {"_D8demangle4testFNhG4fZv", "demangle.test(__vector(float[4]))"},
+      {"_D8demangle4testFNhG8fZv", "demangle.test(__vector(float[8]))"},
+      {"_D8demangle4testFNhG1dZv", "demangle.test(__vector(double[1]))"},
+      {"_D8demangle4testFNhG2dZv", "demangle.test(__vector(double[2]))"},
+      {"_D8demangle4testFNhG4dZv", "demangle.test(__vector(double[4]))"},
+      {"_D8demangle4testFC5classZv", "demangle.test(class)"},
+      {"_D8demangle4testFC5class4testZv", "demangle.test(class.test)"},
+      {"_D8demangle4testFS6structZv", "demangle.test(struct)"},
+      {"_D8demangle4testFS6struct4testZv", "demangle.test(struct.test)"},
+      {"_D8demangle4testFE4enumZv", "demangle.test(enum)"},
+      {"_D8demangle4testFE4enum4testZv", "demangle.test(enum.test)"},
+      {"_D8demangle4testFT7typedefZv", "demangle.test(typedef)"},
+      {"_D8demangle4testFT7typedef4testZv", "demangle.test(typedef.test)"},
+      {"_D8demangle4testFIaZv", "demangle.test(in char)"},
+      {"_D8demangle4testFIKaZv", "demangle.test(in ref char)"},
+      {"_D8demangle4testFJaZv", "demangle.test(out char)"},
+      {"_D8demangle4testFKaZv", "demangle.test(ref char)"},
+      {"_D8demangle4testFLaZv", "demangle.test(lazy char)"},
+      {"_D8demangle4testFMaZv", "demangle.test(scope char)"},
+      {"_D8demangle4testFNjaZv", "demangle.test(char)"},
+      {"_D8demangle4testFNkaZv", "demangle.test(return char)"},
+      {"_D8demangle4testFNlaZv", "demangle.test(char)"},
+      {"_D8demangle4testFaXv", "demangle.test(char...)"},
+      {"_D8demangle4testFaYv", "demangle.test(char, ...)"},
+      {"_D8demangle4testFaaYv", "demangle.test(char, char, ...)"},
+      {"_D8demangle4testFYv", "demangle.test(...)"},
+      {"_D8demangle4testFaaZv", "demangle.test(char, char)"},
+      {"_D8demangle4testFB0Zv", "demangle.test(Tuple!())"},
+      {"_D8demangle4testFB1aZv", "demangle.test(Tuple!(char))"},
+      {"_D8demangle4testFB2aaZv", "demangle.test(Tuple!(char, char))"},
+      {"_D8demangle4testFB3aaaZv", "demangle.test(Tuple!(char, char, char))"},
+      {"_D8demangle4testFB2OaaZv", "demangle.test(Tuple!(shared(char), char))"},
+      {"_D8demangle4testFB3aDFZaaZv",
+       "demangle.test(Tuple!(char, char() delegate, char))"},
+      {"_D8demangle4testFDFZaZv", "demangle.test(char() delegate)"},
+      {"_D8demangle4testFDUZaZv", "demangle.test(extern(C) char() delegate)"},
+      {"_D8demangle4testFDWZaZv",
+       "demangle.test(extern(Windows) char() delegate)"},
+      {"_D8demangle4testFDVZaZv",
+       "demangle.test(extern(Pascal) char() delegate)"},
+      {"_D8demangle4testFDRZaZv", "demangle.test(extern(C++) char() delegate)"},
+      {"_D8demangle4testFDYZaZv",
+       "demangle.test(extern(Objective-C) char() delegate)"},
+      {"_D8demangle4testFPFZaZv", "demangle.test(char() function)"},
+      {"_D8demangle4testFPUZaZv", "demangle.test(extern(C) char() function)"},
+      {"_D8demangle4testFPWZaZv",
+       "demangle.test(extern(Windows) char() function)"},
+      {"_D8demangle4testFPVZaZv",
+       "demangle.test(extern(Pascal) char() function)"},
+      {"_D8demangle4testFPRZaZv", "demangle.test(extern(C++) char() function)"},
+      {"_D8demangle4testFPYZaZv",
+       "demangle.test(extern(Objective-C) char() function)"},
+      {"_D8demangle4testFDFNaZaZv", "demangle.test(char() pure delegate)"},
+      {"_D8demangle4testFDFNbZaZv", "demangle.test(char() nothrow delegate)"},
+      {"_D8demangle4testFDFNcZaZv", "demangle.test(char() ref delegate)"},
+      {"_D8demangle4testFDFNdZaZv", "demangle.test(char() @property delegate)"},
+      {"_D8demangle4testFDFNeZaZv", "demangle.test(char() @trusted delegate)"},
+      {"_D8demangle4testFDFNfZaZv", "demangle.test(char() @safe delegate)"},
+      {"_D8demangle4testFDFNiZaZv", "demangle.test(char() @nogc delegate)"},
+      {"_D8demangle4testFDFNmZaZv", "demangle.test(char() @live delegate)"},
+      {"_D8demangle4testFDFNaNbZaZv",
+       "demangle.test(char() pure nothrow delegate)"},
+      {"_D8demangle4testFDFNbNaZaZv",
+       "demangle.test(char() nothrow pure delegate)"},
+      {"_D8demangle4testFDFNdNfNaZaZv",
+       "demangle.test(char() @property @safe pure delegate)"},
+      {"_D8demangle4testFNjDFZaZv", "demangle.test(char() delegate)"},
+      {"_D8demangle4testFNkDFZaZv", "demangle.test(return char() delegate)"},
+      {"_D8demangle4testFDFNjZaZv", "demangle.test(char() return delegate)"},
+      {"_D8demangle4testFNjNkDFNjZaZv",
+       "demangle.test(return char() return delegate)"},
+      {"_D8demangle4testFNlDFZaZv", "demangle.test(char() delegate)"},
+      {"_D8demangle4testFMDFZaZv", "demangle.test(scope char() delegate)"},
+      {"_D8demangle4testFDFNlZaZv", "demangle.test(char() scope delegate)"},
+      {"_D8demangle4testFMDFNlZaZv",
+       "demangle.test(scope char() scope delegate)"},
+      {"_D8demangle4testFNlMDFNlZaZv",
+       "demangle.test(scope char() scope delegate)"},
+      {"_D8demangle4testFPFNaZaZv", "demangle.test(char() pure function)"},
+      {"_D8demangle4testFPFNbZaZv", "demangle.test(char() nothrow function)"},
+      {"_D8demangle4testFPFNcZaZv", "demangle.test(char() ref function)"},
+      {"_D8demangle4testFPFNdZaZv", "demangle.test(char() @property function)"},
+      {"_D8demangle4testFPFNeZaZv", "demangle.test(char() @trusted function)"},
+      {"_D8demangle4testFPFNfZaZv", "demangle.test(char() @safe function)"},
+      {"_D8demangle4testFPFNiZaZv", "demangle.test(char() @nogc function)"},
+      {"_D8demangle4testFPFNmZaZv", "demangle.test(char() @live function)"},
+      {"_D8demangle4testFPFNaNbZaZv",
+       "demangle.test(char() pure nothrow function)"},
+      {"_D8demangle4testFPFNbNaZaZv",
+       "demangle.test(char() nothrow pure function)"},
+      {"_D8demangle4testFPFNdNfNaZaZv",
+       "demangle.test(char() @property @safe pure function)"},
+      {"_D8demangle4testFNjPFZaZv", "demangle.test(char() function)"},
+      {"_D8demangle4testFNkPFZaZv", "demangle.test(return char() function)"},
+      {"_D8demangle4testFPFNjZaZv", "demangle.test(char() return function)"},
+      {"_D8demangle4testFNjNkPFNjZaZv",
+       "demangle.test(return char() return function)"},
+      {"_D8demangle4testFNlPFZaZv", "demangle.test(char() function)"},
+      {"_D8demangle4testFMPFZaZv", "demangle.test(scope char() function)"},
+      {"_D8demangle4testFPFNlZaZv", "demangle.test(char() scope function)"},
+      {"_D8demangle4testFMPFNlZaZv",
+       "demangle.test(scope char() scope function)"},
+      {"_D8demangle4testFNlMPFNlZaZv",
+       "demangle.test(scope char() scope function)"},
+      {"_D8demangle4test6__initZ", "initializer for demangle.test"},
+      {"_D8demangle4test6__vtblZ", "vtable for demangle.test"},
+      {"_D8demangle4test7__ClassZ", "ClassInfo for demangle.test"},
+      {"_D8demangle4test11__InterfaceZ", "Interface for demangle.test"},
+      {"_D8demangle4test12__ModuleInfoZ", "ModuleInfo for demangle.test"},
+      {"_D8demangle4test6__ctorMFZv", "demangle.test.this()"},
+      {"_D8demangle4test6__dtorMFZv", "demangle.test.~this()"},
+      {"_D8demangle4test10__postblitMFZv", "demangle.test.this(this)"},
+      {"_D8demangle4testFHAbaZv", "demangle.test(char[bool[]])"},
+      {"_D8demangle4testFHG42caZv", "demangle.test(char[creal[42]])"},
+      {"_D8demangle4testFAiXv", "demangle.test(int[]...)"},
+      {"_D8demangle4testFLAiXv", "demangle.test(lazy int[]...)"},
+      {"_D8demangle4testFAiYv", "demangle.test(int[], ...)"},
+      {"_D8demangle4testFLAiYv", "demangle.test(lazy int[], ...)"},
+      {"_D8demangle4testFLilZv", "demangle.test(lazy int, long)"},
+      {"_D8demangle4testFLliZv", "demangle.test(lazy long, int)"},
+      {"_D8demangle4testFLC6ObjectLDFLiZiZi",
+       "demangle.test(lazy Object, lazy int(lazy int) delegate)"},
+      {"_D8demangle9__T4testZv", "demangle.test!()"},
+      {"_D8demangle9__U4testZv", "demangle.test!()"},
+      {"_D8demangle11__T4testTaZv", "demangle.test!(char)"},
+      {"_D8demangle13__T4testTaTaZv", "demangle.test!(char, char)"},
+      {"_D8demangle15__T4testTaTaTaZv", "demangle.test!(char, char, char)"},
+      {"_D8demangle16__T4testTaTOiTaZv",
+       "demangle.test!(char, shared(int), char)"},
+      {"_D8demangle17__T4testS6symbolZv", "demangle.test!(symbol)"},
+      {"_D8demangle23__T4testS116symbol3fooZv", "demangle.test!(symbol.foo)"},
+      {"_D8demangle32__T4testS20_D6symbol3foo3barFZvZv",
+       "demangle.test!(symbol.foo.bar())"},
+      {"_D8demangle19__T4testTaS6symbolZv", "demangle.test!(char, symbol)"},
+      {"_D8demangle19__T4testS6symbolTaZv", "demangle.test!(symbol, char)"},
+      {"_D8demangle12__T4testHTaZv", "demangle.test!(char)"},
+      {"_D8demangle13__T4testVPinZv", "demangle.test!(null)"},
+      {"_D8demangle15__T4testVgi123Zv", "demangle.test!(123)"},
+      {"_D8demangle15__T4testVii123Zv", "demangle.test!(123)"},
+      {"_D8demangle15__T4testVsi123Zv", "demangle.test!(123)"},
+      {"_D8demangle15__T4testVhi123Zv", "demangle.test!(123u)"},
+      {"_D8demangle15__T4testVki123Zv", "demangle.test!(123u)"},
+      {"_D8demangle15__T4testVti123Zv", "demangle.test!(123u)"},
+      {"_D8demangle15__T4testVli123Zv", "demangle.test!(123L)"},
+      {"_D8demangle15__T4testVmi123Zv", "demangle.test!(123uL)"},
+      {"_D8demangle15__T4testViN123Zv", "demangle.test!(-123)"},
+      {"_D8demangle15__T4testVkN123Zv", "demangle.test!(-123u)"},
+      {"_D8demangle15__T4testVlN123Zv", "demangle.test!(-123L)"},
+      {"_D8demangle15__T4testVmN123Zv", "demangle.test!(-123uL)"},
+      {"_D8demangle13__T4testVbi1Zv", "demangle.test!(true)"},
+      {"_D8demangle13__T4testVbi0Zv", "demangle.test!(false)"},
+      {"_D8demangle14__T4testVai10Zv", "demangle.test!('\\x0a')"},
+      {"_D8demangle14__T4testVai32Zv", "demangle.test!(' ')"},
+      {"_D8demangle14__T4testVai65Zv", "demangle.test!('A')"},
+      {"_D8demangle15__T4testVai126Zv", "demangle.test!('~')"},
+      {"_D8demangle16__T4testVui1000Zv", "demangle.test!('\\u03e8')"},
+      {"_D8demangle18__T4testVwi100000Zv", "demangle.test!('\\U000186a0')"},
+      {"_D8demangle17__T4testVde0A8P6Zv", "demangle.test!(0x0.A8p6)"},
+      {"_D8demangle16__T4testVdeA8P2Zv", "demangle.test!(0xA.8p2)"},
+      {"_D8demangle18__T4testVdeN0A8P6Zv", "demangle.test!(-0x0.A8p6)"},
+      {"_D8demangle31__T4testVde0F6E978D4FDF3B646P7Zv",
+       "demangle.test!(0x0.F6E978D4FDF3B646p7)"},
+      {"_D8demangle15__T4testVdeNANZv", "demangle.test!(NaN)"},
+      {"_D8demangle15__T4testVdeINFZv", "demangle.test!(Inf)"},
+      {"_D8demangle16__T4testVdeNINFZv", "demangle.test!(-Inf)"},
+      {"_D8demangle23__T4testVfe0FFFFFFP128Zv",
+       "demangle.test!(0x0.FFFFFFp128)"},
+      {"_D8demangle32__T4testVde0FFFFFFFFFFFFF8P1024Zv",
+       "demangle.test!(0x0.FFFFFFFFFFFFF8p1024)"},
+      {"_D8demangle19__T4testVfe08PN125Zv", "demangle.test!(0x0.8p-125)"},
+      {"_D8demangle20__T4testVde08PN1021Zv", "demangle.test!(0x0.8p-1021)"},
+      {"_D8demangle51__T4testVrc0C4CCCCCCCCCCCCCDP4c0B666666666666666P6Zv",
+       "demangle.test!(0x0.C4CCCCCCCCCCCCCDp4+0x0.B666666666666666p6i)"},
+      {"_D8demangle52__T4testVrcN0C4CCCCCCCCCCCCCDP4c0B666666666666666P6Zv",
+       "demangle.test!(-0x0.C4CCCCCCCCCCCCCDp4+0x0.B666666666666666p6i)"},
+      {"_D8demangle91__"
+       "T4testVde000111222333444555666777888999AAABBBCCCDDDEEEFFFP0001112223334"
+       "44555666777888999Zv",
+       "demangle.test!(0x0."
+       "00111222333444555666777888999AAABBBCCCDDDEEEFFFp00011122233344455566677"
+       "7888999)"},
+      {"_D8demangle22__T4testVG3ua3_616263Zv", "demangle.test!(\"abc\")"},
+      {"_D8demangle22__T4testVG3ud3_616263Zv", "demangle.test!(\"abc\"d)"},
+      {"_D8demangle22__T4testVG3uw3_616263Zv", "demangle.test!(\"abc\"w)"},
+      {"_D8demangle16__T4testVAyaa0_Zv", "demangle.test!(\"\")"},
+      {"_D8demangle32__T4testVAyaa8_20090a0d0c0b00ffZv",
+       "demangle.test!(\" \\t\\n\\r\\f\\v\\x00\\xff\")"},
+      {"_D8demangle22__T4testVAiA4i1i2i3i4Zv", "demangle.test!([1, 2, 3, 4])"},
+      {"_D8demangle25__T4testVAdA2e08P1eN08P1Zv",
+       "demangle.test!([0x0.8p1, -0x0.8p1])"},
+      {"_D8demangle23__T4testVHiiA2i1i2i3i4Zv", "demangle.test!([1:2, 3:4])"},
+      {"_D8demangle39__T4testVHAxaiA2a3_616263i1a3_646566i2Zv",
+       "demangle.test!([\"abc\":1, \"def\":2])"},
+      {"_D8demangle28__T4testVS8demangle1SS2i1i2Zv",
+       "demangle.test!(demangle.S(1, 2))"},
+      {"_D8demangle35__T4testVS8demangle1SS2i1a3_616263Zv",
+       "demangle.test!(demangle.S(1, \"abc\"))"},
+      {"_D8demangle13__T4testTFZaZ6mangleFZv",
+       "demangle.test!(char() function).mangle()"},
+      {"_D8demangle4testMxFZv", "demangle.test() const"},
+      {"_D8demangle4testMyFZv", "demangle.test() immutable"},
+      {"_D8demangle4testMNgFZv", "demangle.test() inout"},
+      {"_D8demangle4testMNgxFZv", "demangle.test() inout const"},
+      {"_D8demangle4testMOFZv", "demangle.test() shared"},
+      {"_D8demangle4testMOxFZv", "demangle.test() shared const"},
+      {"_D8demangle4testMONgFZv", "demangle.test() shared inout"},
+      {"_D8demangle4testMONgxFZv", "demangle.test() shared inout const"},
+      {"_D8demangle4testFDxFZaZv", "demangle.test(char() delegate const)"},
+      {"_D8demangle4testFDyFZaZv", "demangle.test(char() delegate immutable)"},
+      {"_D8demangle4testFDNgFZaZv", "demangle.test(char() delegate inout)"},
+      {"_D8demangle4testFDNgxFZaZv",
+       "demangle.test(char() delegate inout const)"},
+      {"_D8demangle4testFDOFZaZv", "demangle.test(char() delegate shared)"},
+      {"_D8demangle4testFDOxFZaZv",
+       "demangle.test(char() delegate shared const)"},
+      {"_D8demangle4testFDONgFZaZv",
+       "demangle.test(char() delegate shared inout)"},
+      {"_D8demangle4testFDONgxFZaZv",
+       "demangle.test(char() delegate shared inout const)"},
+      {"_D8demangle004testFaZv", "demangle.test(char)"},
+      {"_D8demangle000000004testFaZv", "demangle.test(char)"}};
+
+  for (ExpectedVal Val : ExpectedArray) {
+    char *Demangled = llvm::dlangDemangle(Val.Mangled);
+    EXPECT_STREQ(Demangled, Val.Expected);
+    std::free(Demangled);
+  }
+}