SCons: Fix get_compiler_version() to return ints

Otherwise comparisons would fail for compiler versions above 10.
Also simplified code somewhat to avoid using subprocess too much
needlessly.

(cherry picked from commits c7dc5142b56b3f52ba9c2746eb4855fae68ed26e
and df7ecfc4a7f8403144be2aa49bb47f9ead25926b)

SConstruct

@@ -350,12 +350,13 @@ if selected_platform in platform_list:
         # Force to use Unicode encoding
         env.Append(MSVC_FLAGS=['/utf8'])
     else: # Rest of the world
+        version = methods.get_compiler_version(env) or [-1, -1]
+
         shadow_local_warning = []
         all_plus_warnings = ['-Wwrite-strings']
 
         if methods.using_gcc(env):
-            version = methods.get_compiler_version(env)
-            if version != None and version[0] >= '7':
+            if version[0] >= 7:
                 shadow_local_warning = ['-Wshadow-local']
 
         if (env["warnings"] == 'extra'):
@@ -369,8 +370,7 @@ if selected_platform in platform_list:
                     '-Wduplicated-branches', '-Wduplicated-cond',
                     '-Wstringop-overflow=4', '-Wlogical-op'])
                 env.Append(CXXFLAGS=['-Wnoexcept', '-Wplacement-new=1'])
-                version = methods.get_compiler_version(env)
-                if version != None and version[0] >= '9':
+                if version[0] >= 9:
                     env.Append(CCFLAGS=['-Wattribute-alias=2'])
         elif (env["warnings"] == 'all'):
             env.Append(CCFLAGS=['-Wall'] + shadow_local_warning)

methods.py

@@ -1,5 +1,4 @@
 import os
-import os.path
 import re
 import glob
 import subprocess
@@ -626,14 +625,23 @@ def detect_darwin_sdk_path(platform, env):
             raise
 
 def get_compiler_version(env):
-    # Not using this method on clang because it returns 4.2.1 # https://reviews.llvm.org/D56803
-    if using_gcc(env):
-        version = decode_utf8(subprocess.check_output([env['CXX'], '-dumpversion']).strip())
-    else:
-        version = decode_utf8(subprocess.check_output([env['CXX'], '--version']).strip())
-    match = re.search('[0-9][0-9.]*', version)
+    """
+    Returns an array of version numbers as ints: [major, minor, patch].
+    The return array should have at least two values (major, minor).
+    """
+    if not env.msvc:
+        # Not using -dumpversion as some GCC distros only return major, and
+        # Clang used to return hardcoded 4.2.1: # https://reviews.llvm.org/D56803
+        try:
+            version = decode_utf8(subprocess.check_output([env.subst(env['CXX']), '--version']).strip())
+        except (subprocess.CalledProcessError, OSError):
+            print("Couldn't parse CXX environment variable to infer compiler version.")
+            return None
+    else:  # TODO: Implement for MSVC
+        return None
+    match = re.search('[0-9]+\.[0-9.]+', version)
     if match is not None:
-        return match.group().split('.')
+        return list(map(int, match.group().split('.')))
     else:
         return None
 

platform/x11/detect.py

@@ -180,15 +180,14 @@ def configure(env):
     env.Append(LINKFLAGS=['-pipe'])
 
     # Check for gcc version >= 6 before adding -no-pie
+    version = get_compiler_version(env) or [-1, -1]
     if using_gcc(env):
-        version = get_compiler_version(env)
-        if version != None and version[0] >= '6':
+        if version[0] >= 6:
             env.Append(CCFLAGS=['-fpie'])
             env.Append(LINKFLAGS=['-no-pie'])
     # Do the same for clang should be fine with Clang 4 and higher
     if using_clang(env):
-        version = get_compiler_version(env)
-        if version != None and version[0] >= '4':
+        if version[0] >= 4:
             env.Append(CCFLAGS=['-fpie'])
             env.Append(LINKFLAGS=['-no-pie'])