remove Demangle/StringView.h

[nickdesaulniers]

Summary

Now that we've converted libcxxabi and llvm Demangle to use
std::string_view, this code no longer has any users. Bye bye!

[nickdesaulniers]

• fix typo

[nickdesaulniers]

• remove StringView unittests

[nickdesaulniers]

• resolve TODOs, rebase

[MaskRay]

LGTM, but this can only be accepted from a member of #libc_abi

[phosek]

LGTM

[nickdesaulniers]

• rebase

[nickdesaulniers]

• rebase for presubmit testing

libcxxabi/src/demangle/ItaniumDemangle.h

 //===------------------------- ItaniumDemangle.h ----------------*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // Generic itanium demangler library.
 // There are two copies of this file in the source tree.  The one under
 // libcxxabi is the original and the one under llvm is the copy.  Use
+// TODO
 // cp-to-llvm.sh to update the copy.  See README.txt for more details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DEMANGLE_ITANIUMDEMANGLE_H
 #define DEMANGLE_ITANIUMDEMANGLE_H
 
 #include "DemangleConfig.h"

libcxxabi/src/demangle/README.txt

 
 The copy of the demangler in LLVM has some extra stuff that aren't
 needed in libcxxabi (ie, the MSVC demangler, ItaniumPartialDemangler),
 which depend on the shared generic components. Despite these
 differences, we want to keep the "core" generic demangling library
 identical between both copies to simplify development and testing.
 
 If you're working on the generic library, then do the work first in
+TODO
 libcxxabi, then run the cp-to-llvm.sh script in src/demangle. This
 script takes as an optional argument the path to llvm, and copies the
 changes you made to libcxxabi over.  Note that this script just
 blindly overwrites all changes to the generic library in llvm, so be
 careful.
 
 Because the core demangler needs to work in libcxxabi, everything
 needs to be declared in an anonymous namespace (see

libcxxabi/src/demangle/StringView.h

 //===--- StringView.h -------------------------------------------*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // FIXME: Use std::string_view instead when we support C++17.
 // There are two copies of this file in the source tree.  The one under
 // libcxxabi is the original and the one under llvm is the copy.  Use
+// TODO
 // cp-to-llvm.sh to update the copy.  See README.txt for more details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DEMANGLE_STRINGVIEW_H
 #define DEMANGLE_STRINGVIEW_H
 
 #include "DemangleConfig.h"

libcxxabi/src/demangle/Utility.h

 //===--- Utility.h ----------------------------------------------*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // Provide some utility classes for use in the demangler.
 // There are two copies of this file in the source tree.  The one in libcxxabi
+// TODO
 // is the original and the one in llvm is the copy.  Use cp-to-llvm.sh to update
 // the copy.  See README.txt for more details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DEMANGLE_UTILITY_H
 #define DEMANGLE_UTILITY_H
 

libcxxabi/src/demangle/cp-to-llvm.sh

-#!/bin/bash
-
-# Copies the 'demangle' library, excluding 'DemangleConfig.h', to llvm. If no
-# llvm directory is specified, then assume a monorepo layout.
-
-set -e
-
-cd $(dirname $0)
-HDRS="ItaniumDemangle.h ItaniumNodes.def StringView.h Utility.h"
-LLVM_DEMANGLE_DIR=$1
-
-if [[ -z "$LLVM_DEMANGLE_DIR" ]]; then
-    LLVM_DEMANGLE_DIR="../../../llvm/include/llvm/Demangle"
-fi
-
-if [[ ! -d "$LLVM_DEMANGLE_DIR" ]]; then
-    echo "No such directory: $LLVM_DEMANGLE_DIR" >&2
-    exit 1
-fi
-
-read -p "This will overwrite the copies of $FILES in $LLVM_DEMANGLE_DIR; are you sure? [y/N]" -n 1 -r ANSWER
-echo
-
-if [[ $ANSWER =~ ^[Yy]$ ]]; then
-    cp -f README.txt $LLVM_DEMANGLE_DIR
-    chmod -w $LLVM_DEMANGLE_DIR/README.txt
-    for I in $HDRS ; do
-  rm -f $LLVM_DEMANGLE_DIR/$I
-  dash=$(echo "$I---------------------------" | cut -c -27 |\
-       sed 's|[^-]*||')
-  sed -e '1s|^//=*-* .*\..* -*.*=*// *$|//===--- '"$I $dash"'-*- mode:c++;eval:(read-only-mode) -*-===//|' \
-      -e '2s|^// *$|//       Do not edit! See README.txt.|' \
-      $I >$LLVM_DEMANGLE_DIR/$I
-  chmod -w $LLVM_DEMANGLE_DIR/$I
-    done
-fi

llvm/include/llvm/Demangle/ItaniumDemangle.h

 //===--- ItaniumDemangle.h -----------*- mode:c++;eval:(read-only-mode) -*-===//
 //       Do not edit! See README.txt.
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // Generic itanium demangler library.
 // There are two copies of this file in the source tree.  The one under
-// libcxxabi is the original and the one under llvm is the copy.  Use
-// cp-to-llvm.sh to update the copy.  See README.txt for more details.
+// libcxxabi doesn't use string_view.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DEMANGLE_ITANIUMDEMANGLE_H
 #define DEMANGLE_ITANIUMDEMANGLE_H
 
 #include <llvm/ADT/StringViewExtras.h>
 

llvm/include/llvm/Demangle/README.txt

 * libcxxabi needs the demangler to implement __cxa_demangle, which is
   part of the itanium ABI spec.
 
 * LLVM needs a copy for a bunch of places, and cannot rely on the
   system's __cxa_demangle because it a) might not be available (i.e.,
   on Windows), and b) may not be up-to-date on the latest language
   features.
 
-The copy of the demangler in LLVM has some extra stuff that aren't
-needed in libcxxabi (ie, the MSVC demangler, ItaniumPartialDemangler),
-which depend on the shared generic components. Despite these
-differences, we want to keep the "core" generic demangling library
-identical between both copies to simplify development and testing.
-
-If you're working on the generic library, then do the work first in
-libcxxabi, then run the cp-to-llvm.sh script in src/demangle. This
-script takes as an optional argument the path to llvm, and copies the
-changes you made to libcxxabi over.  Note that this script just
-blindly overwrites all changes to the generic library in llvm, so be
-careful.
-
-Because the core demangler needs to work in libcxxabi, everything
-needs to be declared in an anonymous namespace (see
-DEMANGLE_NAMESPACE_BEGIN), and you can't introduce any code that
-depends on the libcxx dylib.
+The copy of the demangler in LLVM has some extra stuff that aren't needed in
+libcxxabi (ie, the MSVC demangler, ItaniumPartialDemangler), which depend on
+the shared generic components, and makes use of std::string_view.
+
+Because the core demangler needs to work in libcxxabi, everything needs to be
+declared in an anonymous namespace (see DEMANGLE_NAMESPACE_BEGIN), and you
+can't introduce any code that depends on the libcxx dylib.
 
 FIXME: Now that LLVM is a monorepo, it should be possible to
 de-duplicate this code, and have both LLVM and libcxxabi depend on a
 shared demangler library.
 
 Testing
 -------
 
 The tests are split up between libcxxabi/test/{unit,}test_demangle.cpp, and
 llvm/unittest/Demangle. The llvm directory should only get tests for stuff not
 included in the core library. In the future though, we should probably move all
 the tests to LLVM.
 
 It is also a really good idea to run libFuzzer after non-trivial changes, see
 libcxxabi/fuzz/cxa_demangle_fuzzer.cpp and https://llvm.org/docs/LibFuzzer.html.

llvm/include/llvm/Demangle/StringView.h

-//===--- StringView.h ----------------*- mode:c++;eval:(read-only-mode) -*-===//
-//       Do not edit! See README.txt.
-// 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
-//
-//===----------------------------------------------------------------------===//
-//
-// FIXME: Use std::string_view instead when we support C++17.
-// There are two copies of this file in the source tree.  The one under
-// libcxxabi is the original and the one under llvm is the copy.  Use
-// cp-to-llvm.sh to update the copy.  See README.txt for more details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef DEMANGLE_STRINGVIEW_H
-#define DEMANGLE_STRINGVIEW_H
-
-#include "DemangleConfig.h"
-#include <cassert>
-#include <cstring>
-
-DEMANGLE_NAMESPACE_BEGIN
-
-class StringView {
-  const char *First;
-  const char *Last;
-
-public:
-  static const size_t npos = ~size_t(0);
-
-  template <size_t N>
-  StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {}
-  StringView(const char *First_, size_t Len)
-      : First(First_), Last(First_ + Len) {}
-  StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {}
-  StringView() : First(nullptr), Last(nullptr) {}
-
-  StringView substr(size_t Pos, size_t Len = npos) const {
-    assert(Pos <= size());
-    if (Len > size() - Pos)
-      Len = size() - Pos;
-    return StringView(begin() + Pos, Len);
-  }
-
-  size_t find(char C, size_t From = 0) const {
-    // Avoid calling memchr with nullptr.
-    if (From < size()) {
-      // Just forward to memchr, which is faster than a hand-rolled loop.
-      if (const void *P = ::memchr(First + From, C, size() - From))
-        return size_t(static_cast<const char *>(P) - First);
-    }
-    return npos;
-  }
-
-  void remove_prefix(size_t N) {
-    assert(size() >= N);
-    First += N;
-  }
-  void remove_suffix(size_t N) {
-    assert(size() >= N);
-    Last -= N;
-  }
-
-  char front() const {
-    assert(!empty());
-    return *begin();
-  }
-
-  char back() const {
-    assert(!empty());
-    return *(end() - 1);
-  }
-
-  bool startsWith(char C) const { return !empty() && *begin() == C; }
-
-  bool startsWith(StringView Str) const {
-    if (Str.size() > size())
-      return false;
-    return std::strncmp(Str.begin(), begin(), Str.size()) == 0;
-  }
-
-  const char &operator[](size_t Idx) const { return *(begin() + Idx); }
-
-  const char *begin() const { return First; }
-  const char *end() const { return Last; }
-  size_t size() const { return static_cast<size_t>(Last - First); }
-  bool empty() const { return First == Last; }
-};
-
-inline bool operator==(const StringView &LHS, const StringView &RHS) {
-  return LHS.size() == RHS.size() &&
-         std::strncmp(LHS.begin(), RHS.begin(), LHS.size()) == 0;
-}
-
-DEMANGLE_NAMESPACE_END
-
-#endif

llvm/include/llvm/Demangle/Utility.h

 //===--- Utility.h -------------------*- mode:c++;eval:(read-only-mode) -*-===//
 //       Do not edit! See README.txt.
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // Provide some utility classes for use in the demangler.
 // There are two copies of this file in the source tree.  The one in libcxxabi
-// is the original and the one in llvm is the copy.  Use cp-to-llvm.sh to update
-// the copy.  See README.txt for more details.
+// doesn't use string_view.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DEMANGLE_UTILITY_H
 #define DEMANGLE_UTILITY_H
 
 #include "DemangleConfig.h"