From dd4eb5494f7a9a2bd6a29b430a6741da49c51b03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Verschelde?= <rverschelde@gmail.com>
Date: Wed, 26 Feb 2020 07:46:44 +0100
Subject: [PATCH] SCons: Re-allow upcoming GCC 8.4, fixes C++17 copy elision

Follow-up to #36484.

The patches for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86521 have now
landed in the `releases/gcc-8` branch and will be in GCC 8.4.
---
 SConstruct | 20 +++++++++++---------
 methods.py |  6 +++++-
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/SConstruct b/SConstruct
index 9c1644594f4..a5a233fa11d 100644
--- a/SConstruct
+++ b/SConstruct
@@ -334,15 +334,16 @@ if selected_platform in platform_list:
 
     # Enforce our minimal compiler version requirements
     version = methods.get_compiler_version(env)
-    major = int(version[0]) if version is not None else -1
-    if methods.using_gcc(env):
-        # GCC 8 has a regression in the support of guaranteed copy elision
+    if version is not None and methods.using_gcc(env):
+        major = int(version[0])
+        minor = int(version[1])
+        # GCC 8 before 8.4 has a regression in the support of guaranteed copy elision
         # which causes a build failure: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86521
-        if major == 8:
-            print("Detected GCC version 8, which is not supported due to a regression "
-                  "in its C++17 guaranteed copy elision support. Use a newer GCC "
-                  "version, or Clang 6 or later by passing \"use_llvm=yes\" to the "
-                  "SCons command line.")
+        if major == 8 and minor < 4:
+            print("Detected GCC 8 version < 8.4, which is not supported due to a "
+                  "regression in its C++17 guaranteed copy elision support. Use a "
+                  "newer GCC version, or Clang 6 or later by passing \"use_llvm=yes\" "
+                  "to the SCons command line.")
             sys.exit(255)
         elif major < 7:
             print("Detected GCC version older than 7, which does not fully support "
@@ -350,7 +351,8 @@ if selected_platform in platform_list:
                   "version, or Clang 6 or later by passing \"use_llvm=yes\" to the "
                   "SCons command line.")
             sys.exit(255)
-    elif methods.using_clang(env):
+    elif version is not None and methods.using_clang(env):
+        major = int(version[0])
         # Apple LLVM versions differ from upstream LLVM version \o/, compare
         # in https://en.wikipedia.org/wiki/Xcode#Toolchain_versions
         if env["platform"] == "osx" or env["platform"] == "iphone":
diff --git a/methods.py b/methods.py
index 5fdcc2c4b47..2e858e38658 100644
--- a/methods.py
+++ b/methods.py
@@ -557,6 +557,10 @@ def is_vanilla_clang(env):
 
 
 def get_compiler_version(env):
+    """
+    Returns an array of version numbers as strings: [major, minor, patch].
+    The return array should have at least two values (major, minor).
+    """
     if using_gcc(env):
         version = decode_utf8(subprocess.check_output([env['CXX'], '-dumpversion']).strip())
     elif using_clang(env):
@@ -564,7 +568,7 @@ def get_compiler_version(env):
         version = decode_utf8(subprocess.check_output([env['CXX'], '--version']).strip())
     else:  # TODO: Implement for MSVC
         return None
-    match = re.search('[0-9][0-9.]*', version)
+    match = re.search('[0-9]+\.[0-9.]*', version)
     if match is not None:
         return match.group().split('.')
     else: