gcc: simplify version_regex, change string to filter out Apple clang (#45852)

var/spack/repos/builtin/packages/gcc/detection_test.yaml

@@ -82,8 +82,7 @@ paths:
       if [ "$1" = "-dumpversion" ] ; then
         echo "9.3-win32"
       elif [ "$1" = "-dumpfullversion" ] ; then
-        echo "9.3-win32" >&2
+        echo "9.3-win32" 
-        exit 1
       elif [ "$1" = "--version" ] ; then
         echo "i686-w64-mingw32-gcc (GCC) 9.3-win32 20200320"
         echo "Copyright (C) 2019 Free Software Foundation, Inc."
@@ -95,3 +94,28 @@ paths:
       fi
   platforms: [linux]
   results: []
+
+# Homebrew GCC should be detected
+- layout:
+  - executables:
+    - "bin/gcc-14"
+    script: |
+      if [ "$1" = "-dumpversion" ] ; then
+        echo "14"
+      elif [ "$1" = "-dumpfullversion" ] ; then
+        echo "14.1.0" 
+      elif [ "$1" = "--version" ] ; then
+        echo "gcc-14 (Homebrew GCC 14.1.0_2) 14.1.0"
+        echo "Copyright (C) 2024 Free Software Foundation, Inc."
+        echo "This is free software; see the source for copying conditions.  There is NO"
+        echo "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE."
+      else
+        echo "mock executable got an unexpected flag: $1"
+        exit 1
+      fi
+  platforms: [darwin]
+  results:
+    - spec: "gcc@14.1.0 languages=c"
+      extra_attributes:
+        compilers:
+          c: ".*/bin/gcc-14$"

var/spack/repos/builtin/packages/gcc/package.py

@@ -536,7 +536,7 @@ def supported_languages(self):
     d_names = ["gdc"]
     go_names = ["gccgo"]
     compiler_suffixes = [r"-mp-\d+(?:\.\d+)?", r"-\d+(?:\.\d+)?", r"\d\d"]
-    compiler_version_regex = r"(?<!clang version)\s?([0-9.]+)"
+    compiler_version_regex = r"([0-9.]+)"
     compiler_version_argument = ("-dumpfullversion", "-dumpversion")
 
     @classmethod
@@ -549,7 +549,7 @@ def filter_detected_exes(cls, prefix, exes_in_prefix):
                     output = spack.compiler.get_compiler_version_output(exe, "--version")
                 except Exception:
                     output = ""
-                if "Apple" in output:
+                if "clang version" in output:
                     continue
                 not_apple_clang.append(exe)
             return not_apple_clang