[demangler] write-protect non-canonical source

[urnathan]

Summary

To try and void undesired changes to the non-canonical demangler sources, change the cp-to-llvm script to (a) write-protect the target files and (b) prepend 'do not edit' comments that are significant to emacs[*], and hopefully humans.

• bite me :)

[urnathan]

use a single cat with - to concatenate

[ChuanqiXu]

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

28–33

Is the indentation proper?

[serge-sans-paille]

May I suggest an alternate approach: it could be cmake's job to do the copying. That way the LLVM headers would never live in git, and there would be only one source for each of them (?)

[serge-sans-paille]

In D118008#3265195, @serge-sans-paille wrote:

May I suggest an alternate approach: it could be cmake's job to do the copying. That way the LLVM headers would never live in git, and there would be only one source for each of them (?)

But that would mean a cross-project rule, which is probably not a good thing. Forget about it.

[urnathan]

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

28–33

yes, that's a HERE document, so needs the indentation you want the output to have. Upsets the script's indentation as you noticed

[urnathan]

In D118008#3265198, @serge-sans-paille wrote:

In D118008#3265195, @serge-sans-paille wrote:

May I suggest an alternate approach: it could be cmake's job to do the copying. That way the LLVM headers would never live in git, and there would be only one source for each of them (?)

But that would mean a cross-project rule, which is probably not a good thing. Forget about it.

Either that or remove the duplication entirely. Either requires more effort than I have the time for :)

[ChuanqiXu]

This should be good.

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
 
-FILES="ItaniumDemangle.h StringView.h Utility.h README.txt"
+cd $(dirname $0)
+HDRS="ItaniumDemangle.h 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
-    for I in $FILES ; do
-        cp $I $LLVM_DEMANGLE_DIR/$I
+    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
+  cat - $I >$LLVM_DEMANGLE_DIR/$I <<EOF
+// Do not edit! -*- read-only -*-
+// See README.txt for instructions
+EOF
+  chmod -w $LLVM_DEMANGLE_DIR/$I
     done
 fi

llvm/include/llvm/Demangle/ItaniumDemangle.h

+// Do not edit! -*- read-only -*-
+// See README.txt for instructions
 //===------------------------- 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. This file has two byte-per-byte identical
 // copies in the source tree, one in libcxxabi, and the other in llvm.
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_DEMANGLE_ITANIUMDEMANGLE_H
-#define LLVM_DEMANGLE_ITANIUMDEMANGLE_H
+#ifndef DEMANGLE_ITANIUMDEMANGLE_H
+#define DEMANGLE_ITANIUMDEMANGLE_H
 
 // FIXME: (possibly) incomplete list of features that clang mangles that this
 // file does not yet support:
 //   - C++ modules TS
 
 #include "DemangleConfig.h"
 #include "StringView.h"
 #include "Utility.h"

 template <typename Alloc>
 struct ManglingParser : AbstractManglingParser<ManglingParser<Alloc>, Alloc> {
   using AbstractManglingParser<ManglingParser<Alloc>,
                                Alloc>::AbstractManglingParser;
 };
 
 DEMANGLE_NAMESPACE_END
 
-#endif // LLVM_DEMANGLE_ITANIUMDEMANGLE_H
+#endif // DEMANGLE_ITANIUMDEMANGLE_H

llvm/include/llvm/Demangle/StringView.h

+// Do not edit! -*- read-only -*-
+// See README.txt for instructions
 //===--- 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.
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_DEMANGLE_STRINGVIEW_H
-#define LLVM_DEMANGLE_STRINGVIEW_H
+#ifndef DEMANGLE_STRINGVIEW_H
+#define DEMANGLE_STRINGVIEW_H
 
 #include "DemangleConfig.h"
 #include <cassert>
 #include <cstring>
 
 DEMANGLE_NAMESPACE_BEGIN
 
 class StringView {

llvm/include/llvm/Demangle/Utility.h

+// Do not edit! -*- read-only -*-
+// See README.txt for instructions
 //===--- 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(s).
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_DEMANGLE_UTILITY_H
-#define LLVM_DEMANGLE_UTILITY_H
+#ifndef DEMANGLE_UTILITY_H
+#define DEMANGLE_UTILITY_H
 
 #include "StringView.h"
 #include <array>
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
 #include <exception>
 #include <limits>