From 726ea5cf2f7dc9d91b0903fb8996c0d91d524171 Mon Sep 17 00:00:00 2001
From: shahoian <ruben.shahoyan@cern.ch>
Date: Thu, 20 Aug 2026 11:38:04 +0200
Subject: [PATCH] Fix clang post-installation test

Suggested by codex with this explanation

  Clang.sh moves clang into bin-safe, then immediately runs:

  $(clang --print-target-triple)

  But plain clang is no longer in PATH, so the log shows:

  Clang.sh: line 95: clang: command not found
  Clang.sh: line 98: clang: command not found
  Clang.sh: line 101: clang: command not found

  That creates wrongly named config files:

  -clang.cfg
  -clang++.cfg
  -clang-cpp.cfg

  So bin-safe/clang++ does not load the intended --gcc-toolchain config. It falls back to system GCC 12:

  Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12

  but this machine only has C++ headers for GCC 11 under /usr/include/c++/11, not GCC 12, so the final check fails with:

  test.cc:1:10: fatal error: 'iostream' file not found

  I also verified that using the aliBuild GCC toolchain explicitly works:

  clang++ --gcc-toolchain=/home/shahoian/alice/sw/ubuntu2204_x86-64/GCC-Toolchain/v14.2.0-alice2-1 ...

  One more issue: the generated config contains the literal text $GCC_TOOLCHAIN_ROOT; Clang config files did not expand that in my test. So the recipe likely needs both a correct clang path for --print-target-triple and a concrete GCC toolchain path, or another supported relocation mechanism.
---
 clang.sh | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/clang.sh b/clang.sh
index 622b30d717..7ed0e20dae 100644
--- a/clang.sh
+++ b/clang.sh
@@ -111,14 +111,17 @@ rm "$INSTALLROOT"/lib/cmake/clang/*.bak
 # we want to resolve the environment when we run, not when we build this, to avoid
 # relocation issues in case GCC and clang are not built at the same time.
 if [ ! "X$GCC_TOOLCHAIN_ROOT" = X ]; then
-  cat > "$INSTALLROOT/bin-safe/$(clang --print-target-triple)-clang++.cfg" << \EOF
---gcc-toolchain=$GCC_TOOLCHAIN_ROOT
+  target_triple="$("$INSTALLROOT/bin-safe/clang" --print-target-triple)"
+  gcc_toolchain_root="$(eval echo "$GCC_TOOLCHAIN_ROOT")"
+
+  cat > "$INSTALLROOT/bin-safe/${target_triple}-clang++.cfg" << EOF
+--gcc-toolchain=$gcc_toolchain_root
 EOF
-  cat > "$INSTALLROOT/bin-safe/$(clang --print-target-triple)-clang.cfg" << \EOF
---gcc-toolchain=$GCC_TOOLCHAIN_ROOT
+  cat > "$INSTALLROOT/bin-safe/${target_triple}-clang.cfg" << EOF
+--gcc-toolchain=$gcc_toolchain_root
 EOF
-  cat > "$INSTALLROOT/bin-safe/$(clang --print-target-triple)-clang-cpp.cfg" << \EOF
---gcc-toolchain=$GCC_TOOLCHAIN_ROOT
+  cat > "$INSTALLROOT/bin-safe/${target_triple}-clang-cpp.cfg" << EOF
+--gcc-toolchain=$gcc_toolchain_root
 EOF
 fi