[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 >$LLVM_DEMANGLE_DIR/$I <<EOF
+// Do not edit! -*- read-only -*-
+// See README.txt for instructions
+EOF
+        cat $I >>$LLVM_DEMANGLE_DIR/$I
+  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
 //
 //===----------------------------------------------------------------------===//
 //

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
 //
 //===----------------------------------------------------------------------===//
 //

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
 //
 //===----------------------------------------------------------------------===//
 //