compiler-wrapper: set -frandom-seed= in GCC

To make builds deterministic with GCC, use `-frandom-seed` with the
value set to the first positional argument from the command line
(typically the source file, or the output file name)

Signed-off-by: Harmen Stoppels <me@harmenstoppels.nl>

Author: haampie

repos/spack_repo/builtin/packages/compiler_wrapper/cc.sh

@@ -365,20 +365,21 @@ if [ -z "$mode" ] || [ "$mode" = ld ]; then
     done
 fi
 
-# Finish setting up the mode.
+# Finish setting up the mode, and find the first positional arguments as a value
+# for -frandom-seed (to make GCC deterministic)
+_rseed=""
+eval _has_frandom_seed=\${SPACK_${comp}_HAS_FRANDOM_SEED:-}
 if [ -z "$mode" ]; then
     mode=ccld
     for arg in "$@"; do
-        if [ "$arg" = "-E" ]; then
-            mode=cpp
-            break
-        elif [ "$arg" = "-S" ]; then
-            mode=as
-            break
-        elif [ "$arg" = "-c" ]; then
-            mode=cc
-            break
-        fi
+        case $arg in
+            -E) mode=cpp ;;
+            -S) mode=as ;;
+            -c) mode=cc ;;
+            -frandom-seed=*) [ -n "$_has_frandom_seed" ] && _rseed=_set ;;
+            -*|*.h*) ;;
+            *) if [ -n "$_has_frandom_seed" ] && [ -z "$_rseed" ]; then _rseed=$arg; fi ;;
+        esac
     done
 fi
 
@@ -951,6 +952,14 @@ extend args_list libs_list "-l"
 full_command_list="$command"
 extend full_command_list args_list
 
+if [ "$mode" = cc ] && [ -n "$_has_frandom_seed" ]; then
+    case "$_rseed" in
+        _set|'') ;;
+        *) append full_command_list "-frandom-seed=$_rseed" ;;
+    esac
+fi
+unset _rseed _has_frandom_seed
+
 # prepend the ccache binary if we're using ccache
 if [ -n "$SPACK_CCACHE_BINARY" ]; then
     case "$lang_flags" in

repos/spack_repo/builtin/packages/compiler_wrapper/package.py

@@ -40,7 +40,7 @@ class CompilerWrapper(Package):
     if sys.platform != "win32":
         version(
             "1.0",
-            sha256="c7b816479554fd32f677db15ceec6627b91c86074a5d65498688afcbe2796188",
+            sha256="21afdc01e2d8d1f4ea3438ab81b2d3bc16b235c01fbbb9357ac71390ec563b67",
             expand=False,
         )
     else:
@@ -175,6 +175,10 @@ def setup_dependent_build_environment(
             compiler = getattr(compiler_pkg, attr_name)
             env.set(spack_var_name, compiler)
 
+            # -frandom-seed= is needed for deterministic builds with GCC
+            if compiler_pkg.name == "gcc":
+                env.set(f"SPACK_{wrapper_var_name}_HAS_FRANDOM_SEED", "1")
+
             if language not in compiler_pkg.compiler_wrapper_link_paths:
                 continue