Template Instantiation Observer + a few other templight-related changes

[sabel83]

Summary

This patch adds a base-class called TemplateInstantiationObserver which gets notified whenever a template instantiation is entered or exited during semantic analysis. This is a base class used to implement the template profiling and debugging tool called Templight (https://github.com/mikael-s-persson/templight).

The patch also makes a few more changes:

• ActiveTemplateInstantiation class is moved out of the Sema class (so it can be used with inclusion of Sema.h).
• CreateFrontendAction function in front-end utilities is given external linkage (not longer a hidden static function).
• TemplateInstObserverChain data member added to Sema class to hold the list of template-inst observers.
• Notifications to the template-inst observer are added at the key places where templates are instantiated.

I believe this patch should be fairly uncontroversial as the changes are very limited. I tried to keep them minimal, it does not add any end-user feature or bug-fix, and the impact to the main-line code is negligible. AFAIK, all LLVM / Clang guidelines have been respected.

The patch was made against r219658.

[sabel83]

We are working on an interactive shell supporting template metaprogramming, which includes a template metaprogram debugger that needs the functionality this patch provides. Currently our utility is using another implementation of this functionality but we are actively working on migrating our tool to use this patch and therefore its acceptance would make the development and deployment of our utility much easier.

Our application can be found here: https://github.com/sabel83/metashell
The (yet unmerged) branch which migrates to a version of Clang using this patch can be found here: https://github.com/r0mai/metashell

[nlewycky]

There's a few minor cosmetic issues that apply across multiple files:

• Some if-statements have extra spaces inside the parentheses. "if (foo)" not "if ( foo )".
• Some files are inconsistent about * and & placement in types. We usually place them next to the variable names.
• include/clang/Sema/ActiveTemplateInst.h has extra blank lines.

You may find it simplest to use clang-format-diff.py.

I think we'll want a way to test out this interface; it should probably come with a command-line tool that has a very simple template observer that prints out the callbacks as they're called, and a test which runs this tool to exercise it. This might also be a FrontendAction in clang, similar to -ast-dump, instead of a separate tool. (This is not a trivial amount of work, you may want to wait for another clang developer to chime in before spending time on it.)

Overall I'm happy with the design!

include/clang/Sema/TemplateInstObserver.h

25–26 ↗

(On Diff #14850)

Alphabetize.

28 ↗

(On Diff #14850)

What about a callback when clang transitions from parsing the TU to actOnEndOfTranslationUnit? Template instantiation is different before and after we reach the end-of-TU.

lib/Sema/SemaType.cpp

5202

Is there a guarantee that this is a template? Offhand it looks like this could fire on any struct, couldn't it?

[mikael-s-persson]

Thanks for the feedback Nick!

I fixed all the minor cosmetic issues you pointed out, and I also fixed a few "more than 80 char" lines in the original diff.

I changed the name "Observer" to "Callbacks" as requested in the mailing list discussion:
http://clang-developers.42468.n3.nabble.com/Templight-Templight-quot-v2-quot-with-gdb-style-debugger-td4038413.html

Here the new diff (how do I replace the original diff with this one in this llvm-reviews system? I'm new to this system).

templight_clang_patch.diff25 KBDownload

To your comments:

I think we'll want a way to test out this interface; it should probably come with a command-line tool that has a very simple template observer that prints out the callbacks as they're called, and a test which runs this tool to exercise it. This might also be a FrontendAction in clang, similar to -ast-dump, instead of a separate tool. (This is not a trivial amount of work, you may want to wait for another clang developer to chime in before spending time on it.)

That is essentially what I have done for the templight tool (https://github.com/mikael-s-persson/templight). I created a new FrontendAction that creates the templight tracer / debugger as a TemplateInstCallbacks. The templight tracer is essentially what you describe, it dumps a trace of all the callbacks (plus a bit of optional filtering and gathering / pretty-formatting of the information). If you want me to distil it down to a more "raw" tracer that only dumps everything to stdout, then that can easily be done.

But there is one hick-up. If the idea is to use this as a kind of unit-test for the tool, that is, to verify that the trace of callbacks are "correct" (as in, later changes to clang should preserve the same trace), then I think that is a great idea in principle. However, I see two problems with that.

First, it's hard to be sure that the current traces are "correct", as in, maybe this patch has some loop-holes that miss some instantiations, or maybe clang is currently incorrect in some ways that might potentially be fixed in the future (at least, I have seen several "FIXME" notes all over the template instantiation code of the Sema and Parser classes).

Second, according to my tests so far, the traces produced by clang are non-deterministic. Different runs on the same source code will produce different trace files. They only differ in inconsequential ways (different ordering of nested instantiations and memoizations). But the point is that a simple comparison of the trace file with some reference trace file would most certainly always fail, unless the test is really trivial.

Therefore, the notion of what makes a trace "correct" for a given source file is not well-defined, and might never be. But if such a notion could be defined (for example, from the C++ standard), this could end up as a great way to evaluate the correctness of Clang (e.g., "does clang instantiate templates in a standard-compliant way?").

But this is far beyond the scope of this patch.

Alphabetize.

Fixed in new patch.

What about a callback when clang transitions from parsing the TU to actOnEndOfTranslationUnit? Template instantiation is different before and after we reach the end-of-TU.

Thanks for pointing that out. I'm not sure what impact this really has. The initialize / finalize pair of callbacks bracket the entire TU parsing, as far as I know. Therefore, all instantiations are captured by the trace, again, AFAIK. After this comment, I know that there are some late implicit instantiations being instantiated when EOF is reached, basically, right? AFAIK, these are still captured by the callbacks.

I don't know if there is any meaning to a callback at this point. If I were debugging Clang, I might see some value in being able to distinguish the instantiations happening before and after this point. But from the perspective of profiling the template instantiations, I don't really need to know this. In any case, I think that this can be the subject of a future patch if a good concrete use-case / motivation is brought forward. And this also raises the question (maybe more appropriate for cfe-dev mailing list) of whether Clang developers would be interested in using this TemplateInstCallbacks as a means to evaluate / debug the clang compiler itself, which might motivate the addition of more callbacks in it.

Is there a guarantee that this is a template? Offhand it looks like this could fire on any struct, couldn't it?

You are correct in that this callback (for memoizations) picks up a lot of things that are not templates. I am very well aware of this issue and it has been pointed out before, but there is really not a lot I can do to change this. Firstly, memoizations are really important (which I am just beginning to realize after making plans for a call-graph like visualization of the instantiations). Secondly, much of the clang template instantiation code is structured as a "check if instantiated already, if not, instantiate it", which means that there are many many places in clang where some kind of "check if instantiated already" logic exists and it varies greatly from context to context. This makes it very hard to insert the memoization callbacks in proper places. So, as far as I know, this particular placements is not too bad because it picks up most, if not all, checks, and generates noise that can be dealt with (I don't do it currently in templight, but I plan to add that soon, and this is logic that could go into the TemplateInstCallbacks if needed), i.e., it's easier to filter out spurious callbacks than to miss some important ones.

But at the end of the day, the only way that this can be fixed is for someone from the Clang development team who is very much familiar with the complete template instantiation code to provide his/her hands-on assistance for this. I am simply not in a position to be able to figure out how to appropriately trace the memoizations reliably and without too much noise.

[nlewycky]

In D5767#106416, @mikael-s-persson wrote:

Thanks for the feedback Nick!

I fixed all the minor cosmetic issues you pointed out, and I also fixed a few "more than 80 char" lines in the original diff.

I changed the name "Observer" to "Callbacks" as requested in the mailing list discussion:
http://clang-developers.42468.n3.nabble.com/Templight-Templight-quot-v2-quot-with-gdb-style-debugger-td4038413.html

Here the new diff (how do I replace the original diff with this one in this llvm-reviews system? I'm new to this system).

Honestly, I don't know, I tend not to use phabricator myself.

+ / Added for Template instantiation observation
+ / Memoization means we are _not_ instantiating a template because
+ / it is already instantiated (but we entered a context where we
+ / would have had to if it was not already instantiated).
+ Memoization
+
+ } Kind;

Extra newline before "} Kind;".

+ llvm_unreachable("Invalid InstantiationKind!");
+}
+
+
+}

At least one of those newlines is extra.

templight_clang_patch.diff25 KBDownload

To your comments:

I think we'll want a way to test out this interface; it should probably come with a command-line tool that has a very simple template observer that prints out the callbacks as they're called, and a test which runs this tool to exercise it. This might also be a FrontendAction in clang, similar to -ast-dump, instead of a separate tool. (This is not a trivial amount of work, you may want to wait for another clang developer to chime in before spending time on it.)

That is essentially what I have done for the templight tool (https://github.com/mikael-s-persson/templight). I created a new FrontendAction that creates the templight tracer / debugger as a TemplateInstCallbacks. The templight tracer is essentially what you describe, it dumps a trace of all the callbacks (plus a bit of optional filtering and gathering / pretty-formatting of the information). If you want me to distil it down to a more "raw" tracer that only dumps everything to stdout, then that can easily be done.

Yes, a raw tracer is what I had in mind. We could then write the tests with FileCheck. I realize this isn't great as a testing apparatus because you don't want tests to be too closely coupled to implementation details, but we'll need something that exercizes the new code in this patch.

But there is one hick-up. If the idea is to use this as a kind of unit-test for the tool, that is, to verify that the trace of callbacks are "correct" (as in, later changes to clang should preserve the same trace), then I think that is a great idea in principle. However, I see two problems with that.

First, it's hard to be sure that the current traces are "correct", as in, maybe this patch has some loop-holes that miss some instantiations, or maybe clang is currently incorrect in some ways that might potentially be fixed in the future (at least, I have seen several "FIXME" notes all over the template instantiation code of the Sema and Parser classes).

Second, according to my tests so far, the traces produced by clang are non-deterministic.

Non-determinism is a serious problem, I'm surprised we get .o file output as deterministically as we do. Having a mode in clang that exposes the non-determinism to us developers is an important first step in getting the causes found and fixed.

Different runs on the same source code will produce different trace files. They only differ in inconsequential ways (different ordering of nested instantiations and memoizations). But the point is that a simple comparison of the trace file with some reference trace file would most certainly always fail, unless the test is really trivial.

Therefore, the notion of what makes a trace "correct" for a given source file is not well-defined, and might never be. But if such a notion could be defined (for example, from the C++ standard), this could end up as a great way to evaluate the correctness of Clang (e.g., "does clang instantiate templates in a standard-compliant way?").

But this is far beyond the scope of this patch.

Alphabetize.

Fixed in new patch.

What about a callback when clang transitions from parsing the TU to actOnEndOfTranslationUnit? Template instantiation is different before and after we reach the end-of-TU.

Thanks for pointing that out. I'm not sure what impact this really has. The initialize / finalize pair of callbacks bracket the entire TU parsing, as far as I know. Therefore, all instantiations are captured by the trace, again, AFAIK. After this comment, I know that there are some late implicit instantiations being instantiated when EOF is reached, basically, right? AFAIK, these are still captured by the callbacks.

It's more interesting when combined with other features such as PCH or modules. Instantiations which are done before the end-of-TU can be written into a C++ module file and reused by all users of the module while those done after the end-of-TU must be done by every user of the module. For performance we'd like to have more of the former and fewer of the latter. For debugging, there are things we could do to find point-of-instantiation bugs in source code if we defer more instantiation until the end-of-TU, but that isn't in tree*, mainly because clang doesn't do a great job of tracking the PoI.

• I went looking for the patch which isn't in tree and discovered it happened last time I suggested putting instantiation info in the AST! http://marc.info/?l=cfe-dev&m=137246495701597&w=2 .

I don't know if there is any meaning to a callback at this point. If I were debugging Clang, I might see some value in being able to distinguish the instantiations happening before and after this point. But from the perspective of profiling the template instantiations, I don't really need to know this. In any case, I think that this can be the subject of a future patch if a good concrete use-case / motivation is brought forward.

Sounds good.

And this also raises the question (maybe more appropriate for cfe-dev mailing list) of whether Clang developers would be interested in using this TemplateInstCallbacks as a means to evaluate / debug the clang compiler itself, which might motivate the addition of more callbacks in it.

I think the answer has to be yes. Debugging non-determinism inside clang itself should be a good enough motivator.

Is there a guarantee that this is a template? Offhand it looks like this could fire on any struct, couldn't it?

You are correct in that this callback (for memoizations) picks up a lot of things that are not templates. I am very well aware of this issue and it has been pointed out before, but there is really not a lot I can do to change this. Firstly, memoizations are really important (which I am just beginning to realize after making plans for a call-graph like visualization of the instantiations). Secondly, much of the clang template instantiation code is structured as a "check if instantiated already, if not, instantiate it", which means that there are many many places in clang where some kind of "check if instantiated already" logic exists and it varies greatly from context to context. This makes it very hard to insert the memoization callbacks in proper places. So, as far as I know, this particular placements is not too bad because it picks up most, if not all, checks, and generates noise that can be dealt with (I don't do it currently in templight, but I plan to add that soon, and this is logic that could go into the TemplateInstCallbacks if needed), i.e., it's easier to filter out spurious callbacks than to miss some important ones.

But at the end of the day, the only way that this can be fixed is for someone from the Clang development team who is very much familiar with the complete template instantiation code to provide his/her hands-on assistance for this. I am simply not in a position to be able to figure out how to appropriately trace the memoizations reliably and without too much noise.

I agree, I'll let another clang developer handle that one.

[mikael-s-persson]

Made the changes requested by some reviewers.

[klimek]

Is this still the most current patch out there?

[sabel83]

Hi Manuel,

The patch is maintained in the Templight git repository (https://github.com/mikael-s-persson/templight/blob/master/templight_clang_patch.diff). I've written some tests for it (based on our discussion at CppCon), they are under review at the moment (see https://github.com/mikael-s-persson/templight/pull/25 for the details). Note that these are just some initial tests, not covering the entire patch.

[klimek]

Ok, just let me know when you have an updated patch out for review for submission, so I can make sure we'll get the reviews done in a timely fashion. I really want to see this go in :)

[klimek]

Whee, thanks for driving this, much appreciated :D

include/clang/FrontendTool/Utils.h

25

Please add a comment now that this is exported.

include/clang/Sema/TemplateInstCallbacks.h

32 ↗

(On Diff #119377)

Note sure how others think about this, but I'd have expected the design to have:
a) a pure interface
b) an implementation TemplateInstantiationCallbacksCollection or somesuch that has a vector of TICs and forwards calls on them

[sabel83]

I've updated the patch based on your comments.

[klimek]

Ok, I think this is starting to look really good. Now we should try to grab Richard's attention to make sure it's fine to submit with the current set of FIXMEs.

lib/Frontend/FrontendActions.cpp

386

Usually we don't use ascii art. Perhaps instead of marking a scope with arrows, pull out a small function that explains what we want to do instead?

[klimek]

Just FYI, I talked with Richard and he'll not get to it before next week. Hope that's fine.

[klimek]

Weekly ping. This week is C++ committee, so it's again going to be hard to get Richards attention :( It's an unfortunate time of year to land major API-touching changes.

[rsmith]

I'm not entirely sure what's happening with this and https://reviews.llvm.org/D38818, but the direction looks good to me, and I left a couple of comments on the other review thread.

[sabel83]

In D5767#920085, @rsmith wrote:

I'm not entirely sure what's happening with this and https://reviews.llvm.org/D38818, but the direction looks good to me, and I left a couple of comments on the other review thread.

This was the original pull request. I created D38818 when I didn't know how to update this one (it was originally created by Mikael, not me). I have updated D38818 and this one as well based on the comments, so both pull requests have the same code now (and I'll cancel the one that does not get merged).

[rsmith]

LGTM

[xazax.hun]

include/clang/Sema/TemplateInstCallback.h

45

Nit: this file should be clang formatted, it does not follow the LLVM style. (This also applies to some other changes.) Also, I would prefer to remove the trailing underscore from parameter names.

[xazax.hun]

I found some nit, otherwise LG!

I think you should includ the context in the patches, that makes them reviewing much easier. See: https://llvm.org/docs/Phabricator.html#requesting-a-review-via-the-web-interface

include/clang/Sema/TemplateInstCallback.h

48

We usually omit the braces for one line long single statements guarded by ifs.

lib/Frontend/FrontendActions.cpp

464

The methods should start with a lowercase letter even if they are static.

[sabel83]

I have extended the context as suggested.

[sabel83]

I have no commit access, please commit the patch for me.

[xazax.hun]

Overall looks good. Was this tested on large software? I would also be grateful if you could run the regression tests with templight always being enabled to see if they uncover any assertions/crashes.

include/clang/Driver/CC1Options.td

537

Do we want to keep the templight name? I am ok with it, but I wonder if something like dump template instantiation information, or dump template profile information would be more descriptive to the newcomers.

include/clang/Sema/Sema.h

7117

Terminate the first sentence with period.

include/clang/Sema/TemplateInstCallback.h

27

Prefer = default;

lib/Frontend/FrontendActions.cpp

29

Is this header used? If not (after solving my other comments below), please remove it.

319

std::cout is rarely used in LLVM. Did you consider llvm::outs?
Also, do we want to output to the standard output or standard error? Is there other dump functionality that is being printed to the standard output?

357

Some methods still starts with uppercase letters.

377

Use auto * to avoid repeating the type name.

lib/FrontendTool/ExecuteCompilerInvocation.cpp

261

Add namespace closing comment.

lib/Sema/Sema.cpp

40

Do you need to add this include?

lib/Sema/SemaTemplateInstantiate.cpp

204

This function should never be called with Memoization? Maybe this worth a comment?

[sabel83]

This pull requests consists of two parts:

a) a hook, which is called during template instantiation events

b) a callback, which dumps the details of the events out to standard output

Tools like Templight (https://github.com/mikael-s-persson/templight) rely on the hook. The callback is available to make it testable (see the tests, which are part of the pull request) and can be used as a simple way of querying some information about template instantiations if needed.

1. Testing on larger software: Templight is based on the hook and Metashell (http://metashell.org) is using Templight intensively. We have a branch of Metashell using the YAML output for template debugging (https://github.com/sabel83/metashell/tree/use_templight_dump).

2. What do you mean by regression tests? We have run the clang-test target successfully on the patched code (which has the hook). Note that the hook this pull request provides is implemented as a ProgramAction. It is not intended to be used together with other program actions, I don't see how we could turn it on for other tests (if that is what you referred to).

[sabel83]

include/clang/Driver/CC1Options.td

537

As this patch and the related tool has already been presented and referred to as Templight, we prefer keeping the name. Examples:

https://www.youtube.com/watch?v=nUXjVVO4YlA

https://llvm.org/devmtg/2015-04/slides/EuroLLVM2015Templight.pdf

https://baptiste-wicht.com/posts/2016/02/use-templight-and-templar-to-debug-cpp-templates.html

lib/Frontend/FrontendActions.cpp

319

We dump to standard output because the original purpose of this callback is to make the hook itself testable with FileCheck.

[xazax.hun]

In D5767#999143, @sabel83 wrote:

2. What do you mean by regression tests? We have run the clang-test target successfully on the patched code (which has the hook). Note that the hook this pull request provides is implemented as a ProgramAction. It is not intended to be used together with other program actions, I don't see how we could turn it on for other tests (if that is what you referred to).

I would bet the sema tests are full of tricky edge cases. So running templight on those tests would be a helpful exercise. I am only interested in assertion fails, so we do not need to check the output. One option to do so would be to add the -templight-dump option to the %clang_cc1 variable when running the tests. Note that the tests are likely to fail because the output will change, but if there are no crashes, it is fine.

[Szelethus]

lib/Sema/Sema.cpp

40

Yes, in Sema.h the class TemplateInstantiationCallback is only forward declared. That headers contains the definition.

[xazax.hun]

lib/FrontendTool/ExecuteCompilerInvocation.cpp

261

Nit: this should be // namespace clang

[xazax.hun]

lib/Sema/SemaTemplateInstantiate.cpp

646

Use either LLVM_FALLTHROUGH; here or break to avoid compiler warnings.

[Szelethus]

In D5767#1000347, @xazax.hun wrote:

In D5767#999143, @sabel83 wrote:

2. What do you mean by regression tests? We have run the clang-test target successfully on the patched code (which has the hook). Note that the hook this pull request provides is implemented as a ProgramAction. It is not intended to be used together with other program actions, I don't see how we could turn it on for other tests (if that is what you referred to).

I would bet the sema tests are full of tricky edge cases. So running templight on those tests would be a helpful exercise. I am only interested in assertion fails, so we do not need to check the output. One option to do so would be to add the -templight-dump option to the %clang_cc1 variable when running the tests. Note that the tests are likely to fail because the output will change, but if there are no crashes, it is fine.

I did just that, and nothing crashed during the regression tests (in fact, every single one passed)!

[xazax.hun]

Thanks, this looks good to me! I will try this out soon and commit after that.

include/clang/Driver/CC1Options.td

   HelpText<"Build ASTs and then debug dump them">;
 def ast_dump_all : Flag<["-"], "ast-dump-all">,
   HelpText<"Build ASTs and then debug dump them, forcing deserialization">;
+def templight_dump : Flag<["-"], "templight-dump">,
+  HelpText<"Dump templight information to stdout">;
 def ast_dump_lookups : Flag<["-"], "ast-dump-lookups">,
   HelpText<"Build ASTs and then debug dump their name lookup tables">;
 def ast_view : Flag<["-"], "ast-view">,

include/clang/Frontend/FrontendActions.h

   bool hasCodeCompletionSupport() const override { return false; }
 };
 
+class TemplightDumpAction : public ASTFrontendAction {
+protected:
+  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
+                                                 StringRef InFile) override;
+
+  void ExecuteAction() override;
+};
+
 /**
  * \brief Frontend action adaptor that merges ASTs together.
  *

include/clang/Frontend/FrontendOptions.h

     RewriteObjC,            ///< ObjC->C Rewriter.
     RewriteTest,            ///< Rewriter playground
     RunAnalysis,            ///< Run one or more source code analyses.
+    TemplightDump,          ///< Dump template instantiations
     MigrateSource,          ///< Run migrator.
     RunPreprocessorOnly     ///< Just lex, no output.
   };

include/clang/FrontendTool/Utils.h

 #ifndef LLVM_CLANG_FRONTENDTOOL_UTILS_H
 #define LLVM_CLANG_FRONTENDTOOL_UTILS_H
 
+#include <memory>
+
 namespace clang {
 
 class CompilerInstance;
+class FrontendAction;
 
+/// Construct the FrontendAction of a compiler invocation based on the
+/// options specified for the compiler invocation.
+///
+/// \return - The created FrontendAction object
+std::unique_ptr<FrontendAction> CreateFrontendAction(CompilerInstance &CI);
+
 /// ExecuteCompilerInvocation - Execute the given actions described by the
 /// compiler invocation object in the given compiler instance.
 ///

include/clang/Sema/Sema.h

   class TemplateArgumentList;
   class TemplateArgumentLoc;
   class TemplateDecl;
+  class TemplateInstantiationCallback;
   class TemplateParameterList;
   class TemplatePartialOrderingContext;
   class TemplateTemplateParmDecl;

       /// We are defining a synthesized function (such as a defaulted special
       /// member).
       DefiningSynthesizedFunction,
+
+      /// Added for Template instantiation observation
+      /// Memoization means we are _not_ instantiating a template because
+      /// it is already instantiated (but we entered a context where we
+      /// would have had to if it was not already instantiated).
+      Memoization
     } Kind;
 
     /// \brief Was the enclosing context a non-instantiation SFINAE context?

   // FIXME: Does this belong in Sema? It's tough to implement it anywhere else.
   unsigned LastEmittedCodeSynthesisContextDepth = 0;
 
+  /// \brief The template instantiation callbacks to trace or track
+  /// instantiations (objects can be chained).
+  ///
+  /// This callbacks is used to print, trace or track template
+  /// instantiations as they are being constructed.
+  std::vector<std::unique_ptr<TemplateInstantiationCallback>> TemplateInstCallbacks;
+
   /// \brief The current index into pack expansion arguments that will be
   /// used for substitution of parameter packs.
   ///

include/clang/Sema/TemplateInstCallback.h

+//===- TemplateInstCallback.h - Template Instantiation Callback - C++ --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===---------------------------------------------------------------------===//
+//
+// This file defines the TemplateInstantiationCallback class, which is the
+// base class for callbacks that will be notified at template instantiations.
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TEMPLATE_INST_CALLBACK_H
+#define LLVM_CLANG_TEMPLATE_INST_CALLBACK_H
+
+#include "clang/Sema/Sema.h"
+
+namespace clang {
+
+/// \brief This is a base class for callbacks that will be notified at every
+/// template instantiation.
+class TemplateInstantiationCallback {
+public:
+  virtual ~TemplateInstantiationCallback() {}
+
+  /// \brief Called before doing AST-parsing.
+  virtual void initialize(const Sema &TheSema) = 0;
+
+  /// \brief Called after AST-parsing is completed.
+  virtual void finalize(const Sema &TheSema) = 0;
+
+  /// \brief Called when instantiation of a template just began.
+  virtual void atTemplateBegin(const Sema &TheSema,
+                               const Sema::CodeSynthesisContext &Inst) = 0;
+
+  /// \brief Called when instantiation of a template is just about to end.
+  virtual void atTemplateEnd(const Sema &TheSema,
+                             const Sema::CodeSynthesisContext &Inst) = 0;
+};
+
+template <class TemplateInstantiationCallbackPtrs>
+void initialize(TemplateInstantiationCallbackPtrs& Callbacks_, const Sema &TheSema)
+{
+  for (auto& C : Callbacks_)
+  {
+    if (C)
+    {
+      C->initialize(TheSema);
+    }
+  }
+}
+
+template <class TemplateInstantiationCallbackPtrs>
+void finalize(TemplateInstantiationCallbackPtrs& Callbacks_, const Sema &TheSema)
+{
+  for (auto& C : Callbacks_)
+  {
+    if (C)
+    {
+      C->finalize(TheSema);
+    }
+  }
+}
+
+template <class TemplateInstantiationCallbackPtrs>
+void atTemplateBegin(TemplateInstantiationCallbackPtrs& Callbacks_, const Sema &TheSema, const Sema::CodeSynthesisContext &Inst)
+{
+  for (auto& C : Callbacks_)
+  {
+    if (C)
+    {
+      C->atTemplateBegin(TheSema, Inst);
+    }
+  }
+}
+
+template <class TemplateInstantiationCallbackPtrs>
+void atTemplateEnd(TemplateInstantiationCallbackPtrs& Callbacks_, const Sema &TheSema, const Sema::CodeSynthesisContext &Inst)
+{
+  for (auto& C : Callbacks_)
+  {
+    if (C)
+    {
+      C->atTemplateEnd(TheSema, Inst);
+    }
+  }
+}
+
+}
+
+#endif

lib/Frontend/CompilerInvocation.cpp

       Opts.ProgramAction = frontend::PrintPreamble; break;
     case OPT_E:
       Opts.ProgramAction = frontend::PrintPreprocessedInput; break;
+    case OPT_templight_dump:
+      Opts.ProgramAction = frontend::TemplightDump; break;
     case OPT_rewrite_macros:
       Opts.ProgramAction = frontend::RewriteMacros; break;
     case OPT_rewrite_objc:

   case frontend::RewriteObjC:
   case frontend::RewriteTest:
   case frontend::RunAnalysis:
+  case frontend::TemplightDump:
   case frontend::MigrateSource:
     return false;
 

lib/Frontend/FrontendActions.cpp

 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/PreprocessorOptions.h"
+#include "clang/Sema/TemplateInstCallback.h"
 #include "clang/Serialization/ASTReader.h"
 #include "clang/Serialization/ASTWriter.h"
 #include "llvm/Support/FileSystem.h"

 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/YAMLTraits.h"
+#include <iostream>
 #include <memory>
 #include <system_error>
 
 using namespace clang;
 
+namespace
+{
+  CodeCompleteConsumer* GetCodeCompletionConsumer(CompilerInstance& CI)
+  {
+    return CI.hasCodeCompletionConsumer() ?
+           &CI.getCodeCompletionConsumer() : nullptr;
+  }
+
+  void EnsureSemaIsCreated(CompilerInstance& CI, FrontendAction& Action)
+  {
+    if (Action.hasCodeCompletionSupport() &&
+        !CI.getFrontendOpts().CodeCompletionAt.FileName.empty())
+      CI.createCodeCompletionConsumer();
+
+    if (!CI.hasSema())
+      CI.createSema(Action.getTranslationUnitKind(),
+                    GetCodeCompletionConsumer(CI));
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // Custom Actions
 //===----------------------------------------------------------------------===//

 }
 
 namespace {
+  struct TemplightEntry
+  {
+    std::string Name;
+    std::string Kind;
+    std::string Event;
+    std::string PointOfInstantiation;
+  };
+}
+
+namespace llvm {
+namespace yaml {
+  template <>
+  struct MappingTraits<TemplightEntry> {
+    static void mapping(IO &io,
+      TemplightEntry &fields) {
+      io.mapRequired("name", fields.Name);
+      io.mapRequired("kind", fields.Kind);
+      io.mapRequired("event", fields.Event);
+      io.mapRequired("poi", fields.PointOfInstantiation);
+    }
+  };
+}
+}
+
+namespace {
+  class DefaultTemplateInstCallback : public TemplateInstantiationCallback {
+  using CodeSynthesisContext = Sema::CodeSynthesisContext;
+  public:
+    virtual void initialize(const Sema &) {}
+
+    virtual void finalize(const Sema &) {}
+
+    virtual void atTemplateBegin(const Sema &TheSema,
+      const CodeSynthesisContext &Inst) override
+    {
+      DisplayTemplightEntry<true>(std::cout, TheSema, Inst);
+    }
+
+    virtual void atTemplateEnd(const Sema &TheSema,
+      const CodeSynthesisContext &Inst) override
+    {
+      DisplayTemplightEntry<false>(std::cout, TheSema, Inst);
+    }
+  private:
+    static std::string ToString(
+      CodeSynthesisContext::SynthesisKind Kind) {
+      switch (Kind) {
+      case CodeSynthesisContext::TemplateInstantiation:
+        return "TemplateInstantiation";
+      case CodeSynthesisContext::DefaultTemplateArgumentInstantiation:
+        return "DefaultTemplateArgumentInstantiation";
+      case CodeSynthesisContext::DefaultFunctionArgumentInstantiation:
+        return "DefaultFunctionArgumentInstantiation";
+      case CodeSynthesisContext::ExplicitTemplateArgumentSubstitution:
+        return "ExplicitTemplateArgumentSubstitution";
+      case CodeSynthesisContext::DeducedTemplateArgumentSubstitution:
+        return "DeducedTemplateArgumentSubstitution";
+      case CodeSynthesisContext::PriorTemplateArgumentSubstitution:
+        return "PriorTemplateArgumentSubstitution";
+      case CodeSynthesisContext::DefaultTemplateArgumentChecking:
+        return "DefaultTemplateArgumentChecking";
+      case CodeSynthesisContext::ExceptionSpecInstantiation:
+        return "ExceptionSpecInstantiation";
+      case CodeSynthesisContext::DeclaringSpecialMember:
+        return "DeclaringSpecialMember";
+      case CodeSynthesisContext::DefiningSynthesizedFunction:
+        return "DefiningSynthesizedFunction";
+      case CodeSynthesisContext::Memoization:
+        return "Memoization";
+      }
+      return "";
+    }
+
+    template <bool BeginInstantiation>
+    static void DisplayTemplightEntry(std::ostream &Out, const Sema &TheSema,
+      const CodeSynthesisContext &Inst)
+    {
+      std::string YAML;
+      {
+        llvm::raw_string_ostream OS(YAML);
+        llvm::yaml::Output YO(OS);
+        TemplightEntry Entry =
+          GetTemplightEntry<BeginInstantiation>(TheSema, Inst);
+        llvm::yaml::EmptyContext Context;
+        llvm::yaml::yamlize(YO, Entry, true, Context);
+      }
+      Out << "---" << YAML << "\n";
+    }
+
+    template <bool BeginInstantiation>
+    static TemplightEntry GetTemplightEntry(const Sema &TheSema,
+      const CodeSynthesisContext &Inst)
+    {
+      TemplightEntry Entry;
+      Entry.Kind = ToString(Inst.Kind);
+      Entry.Event = BeginInstantiation ? "Begin" : "End";
+      if (NamedDecl* NamedTemplate = dyn_cast_or_null<NamedDecl>(Inst.Entity))
+      {
+        llvm::raw_string_ostream OS(Entry.Name);
+        NamedTemplate->getNameForDiagnostic(OS, TheSema.getLangOpts(), true);
+      }
+      const PresumedLoc Loc =
+        TheSema.getSourceManager().getPresumedLoc(Inst.PointOfInstantiation);
+      if (!Loc.isInvalid())
+      {
+        Entry.PointOfInstantiation =
+          std::string(Loc.getFilename())
+          + ":" + std::to_string(Loc.getLine())
+          + ":" + std::to_string(Loc.getColumn());
+      }
+      return Entry;
+    }
+  };
+}
+
+std::unique_ptr<ASTConsumer>
+TemplightDumpAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
+  return llvm::make_unique<ASTConsumer>();
+}
+
+void TemplightDumpAction::ExecuteAction() {
+  CompilerInstance &CI = getCompilerInstance();
+
+  // This part is normally done by ASTFrontEndAction, but needs to happen
+  // before Templight observers can be created
+  // FIXME: Move the truncation aspect of this into Sema, we delayed this till
+  // here so the source manager would be initialized.
+  EnsureSemaIsCreated(CI, *this);
+
+  CI.getSema().TemplateInstCallbacks.push_back(
+    llvm::make_unique<DefaultTemplateInstCallback>());
+  ASTFrontendAction::ExecuteAction();
+}
+
+namespace {
   /// \brief AST reader listener that dumps module information for a module
   /// file.
   class DumpModuleInfoListener : public ASTReaderListener {

lib/FrontendTool/ExecuteCompilerInvocation.cpp

 using namespace clang;
 using namespace llvm::opt;
 
+namespace clang {
+
 static std::unique_ptr<FrontendAction>
 CreateFrontendBaseAction(CompilerInstance &CI) {
   using namespace clang::frontend;

   case ParseSyntaxOnly:        return llvm::make_unique<SyntaxOnlyAction>();
   case ModuleFileInfo:         return llvm::make_unique<DumpModuleInfoAction>();
   case VerifyPCH:              return llvm::make_unique<VerifyPCHAction>();
+  case TemplightDump:          return llvm::make_unique<TemplightDumpAction>();
 
   case PluginAction: {
     for (FrontendPluginRegistry::iterator it =

 #endif
 }
 
-static std::unique_ptr<FrontendAction>
+std::unique_ptr<FrontendAction>
 CreateFrontendAction(CompilerInstance &CI) {
   // Create the underlying action.
   std::unique_ptr<FrontendAction> Act = CreateFrontendBaseAction(CI);

   return Act;
 }
 
-bool clang::ExecuteCompilerInvocation(CompilerInstance *Clang) {
+bool ExecuteCompilerInvocation(CompilerInstance *Clang) {
   // Honor -help.
   if (Clang->getFrontendOpts().ShowHelp) {
     std::unique_ptr<OptTable> Opts = driver::createDriverOptTable();

     BuryPointer(std::move(Act));
   return Success;
 }
+
+}

lib/Parse/ParseAST.cpp

 #include "clang/Sema/CodeCompleteConsumer.h"
 #include "clang/Sema/Sema.h"
 #include "clang/Sema/SemaConsumer.h"
+#include "clang/Sema/TemplateInstCallback.h"
 #include "llvm/Support/CrashRecoveryContext.h"
 #include <cstdio>
 #include <memory>

   bool OldCollectStats = PrintStats;
   std::swap(OldCollectStats, S.CollectStats);
 
+  // Initialize the template instantiation observer chain.
+  // FIXME: See note on "finalize" below.
+  initialize(S.TemplateInstCallbacks, S);
+
   ASTConsumer *Consumer = &S.getASTConsumer();
 
   std::unique_ptr<Parser> ParseOP(

   
   Consumer->HandleTranslationUnit(S.getASTContext());
 
+  // Finalize the template instantiation observer chain.
+  // FIXME: This (and init.) should be done in the Sema class, but because
+  // Sema does not have a reliable "Finalize" function (it has a
+  // destructor, but it is not guaranteed to be called ("-disable-free")).
+  // So, do the initialization above and do the finalization here:
+  finalize(S.TemplateInstCallbacks, S);
+
   std::swap(OldCollectStats, S.CollectStats);
   if (PrintStats) {
     llvm::errs() << "\nSTATISTICS:\n";

lib/Sema/Sema.cpp

 #include "clang/Sema/SemaConsumer.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/TemplateDeduction.h"
+#include "clang/Sema/TemplateInstCallback.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallSet.h"
 using namespace clang;

lib/Sema/SemaTemplateInstantiate.cpp

 #include "clang/Sema/PrettyDeclStackTrace.h"
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateDeduction.h"
+#include "clang/Sema/TemplateInstCallback.h"
 
 using namespace clang;
 using namespace sema;

   case DeclaringSpecialMember:
   case DefiningSynthesizedFunction:
     return false;
+       
+  case Memoization:
+    break;
   }
 
   llvm_unreachable("Invalid SynthesisKind!");

         !SemaRef.InstantiatingSpecializations
              .insert(std::make_pair(Inst.Entity->getCanonicalDecl(), Inst.Kind))
              .second;
+    atTemplateBegin(SemaRef.TemplateInstCallbacks, SemaRef, Inst);
   }
 }
 

           std::make_pair(Active.Entity, Active.Kind));
     }
 
+    atTemplateEnd(SemaRef.TemplateInstCallbacks,
+        SemaRef, SemaRef.CodeSynthesisContexts.back());
+
     SemaRef.popCodeSynthesisContext();
-
     Invalid = true;
   }
 }

         << cast<CXXRecordDecl>(Active->Entity) << Active->SpecialMember;
       break;
 
-    case CodeSynthesisContext::DefiningSynthesizedFunction:
+    case CodeSynthesisContext::DefiningSynthesizedFunction: {
       // FIXME: For synthesized members other than special members, produce a note.
       auto *MD = dyn_cast<CXXMethodDecl>(Active->Entity);
       auto CSM = MD ? getSpecialMember(MD) : CXXInvalid;

                      diag::note_member_synthesized_at)
           << CSM << Context.getTagDeclType(MD->getParent());
       }
+    }
+
+    case CodeSynthesisContext::Memoization:
       break;
     }
   }

       // This happens in a context unrelated to template instantiation, so
       // there is no SFINAE.
       return None;
+
+    case CodeSynthesisContext::Memoization:
+      break;
     }
 
     // The inner context was transparent for SFINAE. If it occurred within a

lib/Sema/SemaTemplateInstantiateDecl.cpp

 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/PrettyDeclStackTrace.h"
 #include "clang/Sema/Template.h"
+#include "clang/Sema/TemplateInstCallback.h"
 
 using namespace clang;
 

       assert(FunTmpl->getTemplatedDecl() == Tmpl &&
              "Deduction from the wrong function template?");
       (void) FunTmpl;
+      atTemplateEnd(SemaRef.TemplateInstCallbacks, SemaRef, ActiveInst);
       ActiveInst.Kind = ActiveInstType::TemplateInstantiation;
       ActiveInst.Entity = New;
+      atTemplateBegin(SemaRef.TemplateInstCallbacks, SemaRef, ActiveInst);
     }
   }
 

lib/Sema/SemaType.cpp

 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/Template.h"
+#include "clang/Sema/TemplateInstCallback.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringSwitch.h"

         diagnoseMissingImport(Loc, SuggestedDef, MissingImportKind::Definition,
                               /*Recover*/TreatAsComplete);
       return !TreatAsComplete;
+    } else if (Def && !TemplateInstCallbacks.empty()) {
+      CodeSynthesisContext TempInst;
+      TempInst.Kind = CodeSynthesisContext::Memoization;
+      TempInst.Template = Def;
+      TempInst.Entity = Def;
+      TempInst.PointOfInstantiation = Loc;
+      atTemplateBegin(TemplateInstCallbacks, *this, TempInst);
+      atTemplateEnd(TemplateInstCallbacks, *this, TempInst);
     }
 
     return false;

test/Sema/templight-deduced-func.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+
+template <class T>
+int foo(T){return 0;}
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-deduced-func.cpp:}}[[@LINE+28]]{{:12'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-deduced-func.cpp:}}[[@LINE+23]]{{:12'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-deduced-func.cpp:}}[[@LINE+17]]{{:12'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-deduced-func.cpp:}}[[@LINE+12]]{{:12'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-deduced-func.cpp:}}[[@LINE+6]]{{:12'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-deduced-func.cpp:}}[[@LINE+1]]{{:12'$}}
+int gvar = foo(0);

test/Sema/templight-default-arg-inst.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+template<class T, class U = T>
+class A {};
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A::U'$}}
+// CHECK: {{^kind:[ ]+DefaultTemplateArgumentInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+61]]{{:1'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A::U'$}}
+// CHECK: {{^kind:[ ]+DefaultTemplateArgumentInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+56]]{{:1'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A::U'$}}
+// CHECK: {{^kind:[ ]+DefaultTemplateArgumentChecking$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+50]]{{:6'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A::U'$}}
+// CHECK: {{^kind:[ ]+DefaultTemplateArgumentChecking$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+45]]{{:6'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+39]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+34]]{{:8'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+28]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+23]]{{:8'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+17]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+12]]{{:8'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+6]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int, int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-arg-inst.cpp:}}[[@LINE+1]]{{:8'$}}
+A<int> a;

test/Sema/templight-default-func-arg.cpp

+// RUN: %clang_cc1 -std=c++14 -templight-dump %s 2>&1 | FileCheck %s
+template <class T>
+void foo(T b = 0) {};
+
+int main()
+{
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+50]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+45]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+39]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+34]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+28]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+23]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+b$}}
+// CHECK: {{^kind:[ ]+DefaultFunctionArgumentInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+17]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+b$}}
+// CHECK: {{^kind:[ ]+DefaultFunctionArgumentInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+12]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+6]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:}}[[@LINE+1]]{{:3'$}}
+  foo<int>();
+}

test/Sema/templight-default-template-arg.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+template <class T = int>
+class A {};
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A::T'$}}
+// CHECK: {{^kind:[ ]+DefaultTemplateArgumentChecking$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+50]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A::T'$}}
+// CHECK: {{^kind:[ ]+DefaultTemplateArgumentChecking$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+45]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+39]]{{:5'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+34]]{{:5'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+28]]{{:5'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+23]]{{:5'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+17]]{{:5'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+12]]{{:5'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+6]]{{:5'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'A<int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-default-template-arg.cpp:}}[[@LINE+1]]{{:5'$}}
+A<> a;

test/Sema/templight-exception-spec-func.cpp

+// RUN: %clang_cc1 -templight-dump -std=c++14 %s 2>&1 | FileCheck %s
+template <bool B>
+void f() noexcept(B) {}
+
+int main()
+{
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+50]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+45]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+39]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+34]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<false>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+28]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<false>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+23]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<false>'$}}
+// CHECK: {{^kind:[ ]+ExceptionSpecInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+17]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<false>'$}}
+// CHECK: {{^kind:[ ]+ExceptionSpecInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+12]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<false>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+6]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<false>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-exception-spec-func.cpp:}}[[@LINE+1]]{{:3'$}}
+  f<false>();
+}

test/Sema/templight-explicit-template-arg.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+template <class T>
+void f(){}
+
+int main()
+{
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+39]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+34]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+28]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+f$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+23]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+17]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+12]]{{:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+6]]{{:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'f<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-explicit-template-arg.cpp:}}[[@LINE+1]]{{:3'$}}
+  f<int>();
+}

test/Sema/templight-memoization.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+
+template <class T>
+struct foo {};
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-memoization.cpp:}}[[@LINE+6]]{{:10'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-memoization.cpp:}}[[@LINE+1]]{{:10'$}}
+foo<int> x;
+
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK-LABEL: {{^---$}}
+
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-memoization.cpp:}}[[@LINE+6]]{{:10'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-memoization.cpp:}}[[@LINE+1]]{{:10'$}}
+foo<int> y;
+

test/Sema/templight-nested-memoization.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+
+template <int N>
+struct fib
+{
+  static const int value = fib<N-1>::value + fib<N-2>::value;
+};
+
+template <>
+struct fib<0>
+{
+  static const int value = 1;
+};
+
+template <>
+struct fib<1>
+{
+  static const int value = 1;
+};
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<4>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:}}[[@LINE+124]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<4>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:}}[[@LINE+119]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<4>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:}}[[@LINE+114]]{{:8'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<3>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<3>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<3>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<1>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<1>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<0>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:46'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<0>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:46'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<1>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:46'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<1>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:46'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<3>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<3>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<3>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:28'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:46'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'fib<2>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:6:46'$}}
+// CHECK-LABEL: {{^---$}}
+//
+// CHECK: {{^name:[ ]+'fib<4>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-memoization.cpp:}}[[@LINE+1]]{{:8'$}}
+fib<4> x;
+

test/Sema/templight-nested-template-instantiation.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+
+template <int N>
+struct foo : foo<N - 1> {};
+
+template <>
+struct foo<0> {};
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:}}[[@LINE+59]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:}}[[@LINE+54]]{{:8'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:}}[[@LINE+49]]{{:8'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<1>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<1>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<1>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<0>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<0>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<1>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<1>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<1>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:4:14'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<2>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-nested-template-instantiation.cpp:}}[[@LINE+1]]{{:8'$}}
+foo<2> x;

test/Sema/templight-one-instantiation.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+
+template <class T>
+struct foo {};
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-one-instantiation.cpp:}}[[@LINE+6]]{{:10'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-one-instantiation.cpp:}}[[@LINE+1]]{{:10'$}}
+foo<int> x;

test/Sema/templight-prior-template-arg.cpp

+// RUN: %clang_cc1 -templight-dump %s 2>&1 | FileCheck %s
+template<class T>
+class A {};
+
+template <template <class Inner> class Outer>
+class B {};
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B::Outer'$}}
+// CHECK: {{^kind:[ ]+PriorTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+50]]{{:1'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B::Outer'$}}
+// CHECK: {{^kind:[ ]+PriorTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+45]]{{:1'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+39]]{{:6'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+34]]{{:6'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+28]]{{:6'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+23]]{{:6'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+17]]{{:6'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+12]]{{:6'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+6]]{{:6'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'B<A>'$}}
+// CHECK: {{^kind:[ ]+Memoization$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^poi:[ ]+'.*templight-prior-template-arg.cpp:}}[[@LINE+1]]{{:6'$}}
+B<A> b;

tools/CMakeLists.txt

 
 # libclang may require clang-tidy in clang-tools-extra.
 add_clang_subdirectory(libclang)
+add_subdirectory(templight)