WIP: another workaround for hardcoded compiler versions

Author: omajid

eng/common/native/init-compiler.sh

@@ -2,7 +2,9 @@
 #
 # This file detects the C/C++ compiler and exports it to the CC/CXX environment variables
 #
-# NOTE: some scripts source this file and rely on stdout being empty, make sure to not output anything here!
+# NOTE: some scripts source this file and rely on stdout being empty, make sure
+# to not output *anything* here, unless it is an error message that fails the
+# build.
 
 if [ -z "$build_arch" ] || [ -z "$compiler" ]; then
   echo "Usage..."
@@ -62,6 +64,7 @@ if [ -z "$CLR_CC" ]; then
 
     # Set default versions
     if [ -z "$majorVersion" ]; then
+
         # note: gcc (all versions) and clang versions higher than 6 do not have minor version in file name, if it is zero.
         if [ "$compiler" = "clang" ]; then versions="18 17 16 15 14 13 12 11 10 9 8 7 6.0 5.0 4.0 3.9 3.8 3.7 3.6 3.5"
         elif [ "$compiler" = "gcc" ]; then versions="13 12 11 10 9 8 7 6 5 4.9"; fi
@@ -75,11 +78,14 @@ if [ -z "$CLR_CC" ]; then
 
         if [ -z "$majorVersion" ]; then
             if command -v "$compiler" > /dev/null; then
-                if [ "$(uname)" != "Darwin" ]; then
-                    echo "Warning: Specific version of $compiler not found, falling back to use the one in PATH."
-                fi
                 CC="$(command -v "$compiler")"
                 CXX="$(command -v "$cxxCompiler")"
+                version="$("$CC" -dumpversion)"
+                # gcc and clang often display 3 part versions. However, gcc can show only 1 part in some environments.
+                IFS=. read -r majorVersion minorVersion patchVersion <<EOF
+$version
+EOF
+                unset patchVersion
             else
                 echo "No usable version of $compiler found."
                 exit 1
@@ -88,7 +94,6 @@ if [ -z "$CLR_CC" ]; then
             if [ "$compiler" = "clang" ] && [ "$majorVersion" -lt 5 ]; then
                 if [ "$build_arch" = "arm" ] || [ "$build_arch" = "armel" ]; then
                     if command -v "$compiler" > /dev/null; then
-                        echo "Warning: Found clang version $majorVersion which is not supported on arm/armel architectures, falling back to use clang from PATH."
                         CC="$(command -v "$compiler")"
                         CXX="$(command -v "$cxxCompiler")"
                     else
@@ -110,6 +115,12 @@ if [ -z "$CLR_CC" ]; then
         CC="$(command -v "$compiler$desired_version")"
         CXX="$(command -v "$cxxCompiler$desired_version")"
         if [ -z "$CXX" ]; then CXX="$(command -v "$cxxCompiler")"; fi
+        version="$("$CC" -dumpversion)"
+        # gcc and clang often display 3 part versions. However, gcc can show only 1 part in some environments.
+        IFS=. read -r majorVersion minorVersion patchVersion <<EOF
+$version
+EOF
+        unset patchVersion
     fi
 else
     if [ ! -f "$CLR_CC" ]; then