From a87391d2562eaf4fa820df7d211978c6b25dd2c6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Verschelde?= <rverschelde@gmail.com>
Date: Thu, 2 Jan 2025 23:16:09 +0100
Subject: [PATCH] Linux: Allow building with GCC > 8, only GCC 6/7 trigger the
 `Object::cast_to` optimization issue

And likewise, prevent building with mingw-gcc for Windows if it's GCC 6/7.

The check for the Server platform was unnecessary as its `release` template
doesn't use `-O3`/`-Ofast`.
---
 platform/server/detect.py  | 10 ----------
 platform/windows/detect.py | 12 ++++++++++++
 platform/x11/detect.py     | 22 ++++++++++++----------
 3 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/platform/server/detect.py b/platform/server/detect.py
index 3afbd01133b..28f0956746a 100644
--- a/platform/server/detect.py
+++ b/platform/server/detect.py
@@ -40,16 +40,6 @@ def configure(env):
         env["CC"] = "clang"
         env["CXX"] = "clang++"
         env["LD"] = "clang++"
-    elif (os.system("gcc --version > /dev/null 2>&1") == 0): # GCC
-        # Hack to prevent building this branch with GCC 6+, which trigger segfaults due to UB when dereferencing pointers in Object::cast_to
-        # This is fixed in the master branch, for 2.1 we just prevent using too recent GCC versions.
-        import subprocess
-        gcc_major = subprocess.check_output(['gcc', '-dumpversion']).decode('ascii').split('.')[0]
-        if (int(gcc_major) > 5):
-            print("Your configured compiler appears to be GCC %s, which triggers issues in release builds for this version of Godot (fixed in Godot 3.0+)." % gcc_major)
-            print("You can use the Clang compiler instead with the `use_llvm=yes` option, or configure another compiler such as GCC 5 using the CC, CXX and LD flags.")
-            print("Aborting..")
-            sys.exit(255)
 
     is64 = sys.maxsize > 2**32
 
diff --git a/platform/windows/detect.py b/platform/windows/detect.py
index a7151235a52..40aa51cac4d 100644
--- a/platform/windows/detect.py
+++ b/platform/windows/detect.py
@@ -326,6 +326,18 @@ def configure(env):
 
             if (env["bits"] == "64"):
                 env.Append(CCFLAGS=['-O3'])
+
+                if (os.system(mingw_prefix + "gcc --version > /dev/null 2>&1") == 0): # GCC
+                    # Hack to prevent segfaults due to UB when dereferencing NULL `this` in `Object::cast_to` with `-O3`.
+                    # This is fixed in 3.0, for 2.1 we just prevent using the known affected GCC versions (6 and 7).
+                    # GCC 5 or GCC 8 and later seem to be fine.
+                    import subprocess
+                    gcc_major = int(subprocess.check_output([mingw_prefix + 'gcc', '-dumpversion']).decode('ascii').split('.')[0])
+                    if (gcc_major == 6 or gcc_major == 7):
+                        print("Your configured compiler appears to be GCC %d, which triggers issues in release builds for this version of Godot (fixed in Godot 3.0+)." % gcc_major)
+                        print("You can use the Clang compiler instead with the `use_llvm=yes` option, or configure another compiler such as GCC 5 using the CC, CXX and LD flags.")
+                        print("Aborting..")
+                        sys.exit(255)
             else:
                 env.Append(CCFLAGS=['-O2'])
 
diff --git a/platform/x11/detect.py b/platform/x11/detect.py
index ab791f357f7..0dfbca11f8b 100644
--- a/platform/x11/detect.py
+++ b/platform/x11/detect.py
@@ -86,16 +86,6 @@ def configure(env):
             env["LD"] = "clang++"
         env.Append(CPPFLAGS=['-DTYPED_METHOD_BIND'])
         env.extra_suffix = ".llvm"
-    elif (os.system("gcc --version > /dev/null 2>&1") == 0): # GCC
-        # Hack to prevent building this branch with GCC 6+, which trigger segfaults due to UB when dereferencing pointers in Object::cast_to
-        # This is fixed in the master branch, for 2.1 we just prevent using too recent GCC versions.
-        import subprocess
-        gcc_major = subprocess.check_output(['gcc', '-dumpversion']).decode('ascii').split('.')[0]
-        if (int(gcc_major) > 5):
-            print("Your configured compiler appears to be GCC %s, which triggers issues in release builds for this version of Godot (fixed in Godot 3.0+)." % gcc_major)
-            print("You can use the Clang compiler instead with the `use_llvm=yes` option, or configure another compiler such as GCC 5 using the CC, CXX and LD flags.")
-            print("Aborting..")
-            sys.exit(255)
 
     if (env["use_sanitizer"] == "yes"):
         env.Append(CCFLAGS=['-fsanitize=address', '-fno-omit-frame-pointer'])
@@ -125,6 +115,18 @@ def configure(env):
         if (env["debug_release"] == "yes"):
             env.Prepend(CCFLAGS=['-g2'])
 
+        if (os.system("gcc --version > /dev/null 2>&1") == 0): # GCC
+            # Hack to prevent segfaults due to UB when dereferencing NULL `this` in `Object::cast_to` with `-O3`.
+            # This is fixed in 3.0, for 2.1 we just prevent using the known affected GCC versions (6 and 7).
+            # GCC 5 or GCC 8 and later seem to be fine.
+            import subprocess
+            gcc_major = int(subprocess.check_output(['gcc', '-dumpversion']).decode('ascii').split('.')[0])
+            if (gcc_major == 6 or gcc_major == 7):
+                print("Your configured compiler appears to be GCC %d, which triggers issues in release builds for this version of Godot (fixed in Godot 3.0+)." % gcc_major)
+                print("You can use the Clang compiler instead with the `use_llvm=yes` option, or configure another compiler such as GCC 5 using the CC, CXX and LD flags.")
+                print("Aborting..")
+                sys.exit(255)
+
     elif (env["target"] == "release_debug"):
 
         env.Prepend(CCFLAGS=['-O2', '-ffast-math', '-DDEBUG_ENABLED'])