Change build script for C++ modules with recent Clang

Author: cpp-tutor

modules/build/build-clang-modules.sh

@@ -1,14 +1,37 @@
 #!/bin/sh
 
 # This script will compile all files with .cpp extension in the parent directory
-# Clang version 12 (or newer) C++ modules version
+# Clang version 16 (or newer) C++ modules version
+
+if [ -z "$CLANG_PREFIX" ] ; then
+  CLANG_PREFIX="/usr"
+fi
+
+if [ -z "$CLANG_PCM" ] ; then
+   CLANG_PCM="./std.pcm"
+fi
+
+CLANG="$CLANG_PREFIX/bin/clang++"
+
+if [ ! -f "$CLANG_PCM" ] ; then
+  echo "Compiling library module..."
+  if [ ! -f "$CLANG_PREFIX/share/libc++/v1/std.cppm" ] ; then
+    echo "Error: Could not find file $CLANG_PREFIX/share/libc++/v1/std.cppm"
+    echo "Please set environment variable CLANG_PREFIX and re-run script"
+    exit 1
+  fi
+    LD_LIBRARY_PATH="$CLANG_PREFIX/lib":"$CLANG_PREFIX/lib/x86_64-unknown-linux-gnu" \
+      "$CLANG" -std=c++23 -stdlib=libc++ -Wno-reserved-identifier -Wno-reserved-module-identifier \
+      --precompile -o "$CLANG_PCM" "$CLANG_PREFIX/share/libc++/v1/std.cppm"
+fi
 
 failures=0
 for PROGRAM in ../*.cpp ; do
   BASE="$(basename $PROGRAM)"
   echo "$BASE..."
   failed=""
-  clang++ -fmodules -std=c++20 -stdlib=libc++ -o ${BASE%.cpp} $PROGRAM >/dev/null 2>&1 || failed="y"
+  LD_LIBRARY_PATH="$CLANG_PREFIX/lib":"$CLANG_PREFIX/lib/x86_64-unknown-linux-gnu" \
+    "$CLANG" -fmodule-file=std="$CLANG_PCM" -std=c++23 -stdlib=libc++ -o ${BASE%.cpp} $PROGRAM || failed="y"
   if [ -n "$failed" ] ; then
     echo "Failed to compile $BASE"
     failures=$((failures+1))