gcc: restore old detection (spack#45810)

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

@@ -52,27 +52,6 @@ paths:
         cxx: ".*/bin/g[+][+]-5$"
         fortran: ".*/bin/gfortran-5$"
 
-# Multiple compilers present at the same time
-- layout:
-  - executables:
-    - "bin/x86_64-linux-gnu-gcc-6"
-    script: 'echo 6.5.0'
-  - executables:
-    - "bin/x86_64-linux-gnu-gcc-10"
-    - "bin/x86_64-linux-gnu-g++-10"
-    script: "echo 10.1.0"
-  platforms: [darwin, linux]
-  results:
-  - spec: "gcc@6.5.0 languages=c"
-    extra_attributes:
-      compilers:
-        c: ".*/bin/x86_64-linux-gnu-gcc-6$"
-  - spec: "gcc@10.1.0 languages=c,c++"
-    extra_attributes:
-      compilers:
-        c: ".*/bin/x86_64-linux-gnu-gcc-10$"
-        cxx: ".*/bin/x86_64-linux-gnu-g[+][+]-10$"
-
 # Apple clang under disguise as gcc should not be detected
 - layout:
   - executables:
@@ -94,3 +73,25 @@ paths:
       fi
   platforms: ["darwin"]
   results: []
+
+# Mingw cross compiler on linux should not be detected
+- layout:
+  - executables:
+    - "bin/i686-w64-mingw32-gcc"
+    script: |
+      if [ "$1" = "-dumpversion" ] ; then
+        echo "9.3-win32"
+      elif [ "$1" = "-dumpfullversion" ] ; then
+        echo "9.3-win32" >&2
+        exit 1
+      elif [ "$1" = "--version" ] ; then
+        echo "i686-w64-mingw32-gcc (GCC) 9.3-win32 20200320"
+        echo "Copyright (C) 2019 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: [linux]
+  results: []

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

@@ -7,7 +7,7 @@
 import os
 import sys
 
-from archspec.cpu import UnsupportedMicroarchitecture
+import archspec.cpu
 
 import llnl.util.tty as tty
 from llnl.util.symlink import readlink
@@ -535,45 +535,26 @@ def supported_languages(self):
     fortran_names = ["gfortran"]
     d_names = ["gdc"]
     go_names = ["gccgo"]
-    compiler_prefixes = [r"\w+-\w+-\w+-"]
     compiler_suffixes = [r"-mp-\d+(?:\.\d+)?", r"-\d+(?:\.\d+)?", r"\d\d"]
     compiler_version_regex = r"(?<!clang version)\s?([0-9.]+)"
     compiler_version_argument = ("-dumpfullversion", "-dumpversion")
 
-    @classmethod
-    def determine_version(cls, exe):
-        try:
-            output = spack.compiler.get_compiler_version_output(exe, "--version")
-        except Exception:
-            output = ""
-        # Apple's gcc is actually apple clang, so skip it.
-        if "Apple" in output:
-            return None
-
-        return super().determine_version(exe)
-
     @classmethod
     def filter_detected_exes(cls, prefix, exes_in_prefix):
-        result = []
-        for exe in exes_in_prefix:
-            # On systems like Ubuntu we might get multiple executables
-            # with the string "gcc" in them. See:
-            # https://helpmanual.io/packages/apt/gcc/
-            basename = os.path.basename(exe)
-            substring_to_be_filtered = [
-                "c99-gcc",
-                "c89-gcc",
-                "-nm",
-                "-ar",
-                "ranlib",
-                "clang",  # clang++ matches g++ -> clan[g++]
-            ]
-            if any(x in basename for x in substring_to_be_filtered):
-                continue
-
-            result.append(exe)
+        # Apple's gcc is actually apple clang, so skip it.
+        if str(spack.platforms.host()) == "darwin":
+            not_apple_clang = []
+            for exe in exes_in_prefix:
+                try:
+                    output = spack.compiler.get_compiler_version_output(exe, "--version")
+                except Exception:
+                    output = ""
+                if "Apple" in output:
+                    continue
+                not_apple_clang.append(exe)
+            return not_apple_clang
 
-        return result
+        return exes_in_prefix
 
     @classmethod
     def determine_variants(cls, exes, version_str):
@@ -702,7 +683,7 @@ def get_common_target_flags(self, spec):
         for uarch in microarchitectures:
             try:
                 return uarch.optimization_flags("gcc", str(spec.version))
-            except UnsupportedMicroarchitecture:
+            except archspec.cpu.UnsupportedMicroarchitecture:
                 pass
         # no arch specific flags in common, unlikely to happen.
         return ""