[SCons] Add warnings build options

.github/workflows/ci.yml

@@ -90,6 +90,7 @@ jobs:
       SCONS_CACHE: ${{ github.workspace }}/.scons-cache/
       EM_VERSION: 3.1.39
       EM_CACHE_FOLDER: "emsdk-cache"
+      SCONSFLAGS: warnings=extra werror=yes
 
     steps:
       - name: Checkout

include/godot_cpp/core/binder_common.hpp

@@ -229,6 +229,13 @@ void call_with_ptr_args(T *p_instance, R (T::*p_method)(P...) const, const GDExt
 	call_with_ptr_args_retc_helper<T, R, P...>(p_instance, p_method, p_args, r_ret, BuildIndexSequence<sizeof...(P)>{});
 }
 
+// GCC raises "parameter 'p_args' set but not used" when P = {},
+// it's not clever enough to treat other P values as making this branch valid.
+#if defined(DEBUG_METHODS_ENABLED) && defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
+#endif
+
 template <class T, class... P, size_t... Is>
 void call_with_variant_args_helper(T *p_instance, void (T::*p_method)(P...), const Variant **p_args, GDExtensionCallError &r_error, IndexSequence<Is...>) {
 	r_error.error = GDEXTENSION_CALL_OK;
@@ -470,13 +477,6 @@ void call_with_variant_args_retc_dv(T *p_instance, R (T::*p_method)(P...) const,
 	call_with_variant_args_retc_helper(p_instance, p_method, argsp.data(), r_ret, r_error, BuildIndexSequence<sizeof...(P)>{});
 }
 
-// GCC raises "parameter 'p_args' set but not used" when P = {},
-// it's not clever enough to treat other P values as making this branch valid.
-#if defined(DEBUG_METHODS_ENABLED) && defined(__GNUC__) && !defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
-#endif
-
 template <class Q>
 void call_get_argument_type_helper(int p_arg, int &index, GDExtensionVariantType &type) {
 	if (p_arg == index) {

include/godot_cpp/core/method_bind.hpp

@@ -605,6 +605,7 @@ class MethodBindTS : public MethodBind {
 #if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wlogical-op"
+#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
 #endif
 	virtual GDExtensionVariantType gen_argument_type(int p_arg) const {
 		if (p_arg >= 0 && p_arg < (int)sizeof...(P)) {

tools/targets.py

@@ -1,4 +1,5 @@
 import os
+import re
 import subprocess
 import sys
 from SCons.Script import ARGUMENTS
@@ -9,6 +10,37 @@
 # Helper methods
 
 
+def get_compiler_version(env):
+    """
+    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.get("is_msvc", False):
+        # 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 = subprocess.check_output([env.subst(env["CXX"]), "--version"]).strip().decode("utf-8")
+        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(
+        "(?:(?<=version )|(?<=\) )|(?<=^))"
+        "(?P<major>\d+)"
+        "(?:\.(?P<minor>\d*))?"
+        "(?:\.(?P<patch>\d*))?"
+        "(?:-(?P<metadata1>[0-9a-zA-Z-]*))?"
+        "(?:\+(?P<metadata2>[0-9a-zA-Z-]*))?"
+        "(?: (?P<date>[0-9]{8}|[0-9]{6})(?![0-9a-zA-Z]))?",
+        version,
+    )
+    if match is not None:
+        return match.groupdict()
+    else:
+        return None
+
+
 def get_cmdline_bool(option, default):
     """We use `ARGUMENTS.get()` to check if options were manually overridden on the command line,
     and SCons' _text2bool helper to convert them to booleans, otherwise they're handled as strings.
@@ -20,6 +52,14 @@ def get_cmdline_bool(option, default):
         return default
 
 
+def using_gcc(env):
+    return "gcc" in os.path.basename(env["CC"])
+
+
+def using_emcc(env):
+    return "emcc" in os.path.basename(env["CC"])
+
+
 def using_clang(env):
     return "clang" in os.path.basename(env["CC"])
 
@@ -49,6 +89,8 @@ def options(opts):
     )
     opts.Add(BoolVariable("debug_symbols", "Build with debugging symbols", True))
     opts.Add(BoolVariable("dev_build", "Developer build with dev-only debugging code (DEV_ENABLED)", False))
+    opts.Add(EnumVariable("warnings", "Level of compilation warnings", "all", ("extra", "all", "moderate", "no")))
+    opts.Add(BoolVariable("werror", "Treat compiler warnings as errors", False))
 
 
 def exists(env):
@@ -115,6 +157,37 @@ def generate(env):
             env.Append(LINKFLAGS=["/OPT:REF"])
         elif env["optimize"] == "debug" or env["optimize"] == "none":
             env.Append(CCFLAGS=["/Od"])
+
+        # Warnings
+        if env["warnings"] == "no":
+            env.Append(CCFLAGS=["/w"])
+        else:
+            if env["warnings"] == "extra":
+                env.Append(CCFLAGS=["/W4"])
+            elif env["warnings"] == "all":
+                env.Append(CCFLAGS=["/W3"])
+            elif env["warnings"] == "moderate":
+                env.Append(CCFLAGS=["/W2"])
+            # Disable warnings which we don't plan to fix.
+
+            env.Append(
+                CCFLAGS=[
+                    "/wd4100",  # C4100 (unreferenced formal parameter): Doesn't play nice with polymorphism.
+                    "/wd4127",  # C4127 (conditional expression is constant)
+                    "/wd4201",  # C4201 (non-standard nameless struct/union): Only relevant for C89.
+                    "/wd4244",  # C4244 C4245 C4267 (narrowing conversions): Unavoidable at this scale.
+                    "/wd4245",
+                    "/wd4267",
+                    "/wd4305",  # C4305 (truncation): double to float or real_t, too hard to avoid.
+                    "/wd4514",  # C4514 (unreferenced inline function has been removed)
+                    "/wd4714",  # C4714 (function marked as __forceinline not inlined)
+                    "/wd4820",  # C4820 (padding added after construct)
+                ]
+            )
+
+        if env["werror"]:
+            env.Append(CCFLAGS=["/WX"])
+
     else:
         if env["debug_symbols"]:
             # Adding dwarf-4 explicitly makes stacktraces work with clang builds,
@@ -142,3 +215,64 @@ def generate(env):
             env.Append(CCFLAGS=["-Og"])
         elif env["optimize"] == "none":
             env.Append(CCFLAGS=["-O0"])
+
+        # Warnings
+        cc_version = get_compiler_version(env) or {
+            "major": None,
+            "minor": None,
+            "patch": None,
+            "metadata1": None,
+            "metadata2": None,
+            "date": None,
+        }
+        cc_version_major = int(cc_version["major"] or -1)
+        cc_version_minor = int(cc_version["minor"] or -1)
+
+        common_warnings = []
+
+        if using_gcc(env):
+            common_warnings += ["-Wshadow-local", "-Wno-misleading-indentation"]
+            if cc_version_major == 7:  # Bogus warning fixed in 8+.
+                common_warnings += ["-Wno-strict-overflow"]
+            if cc_version_major < 11:
+                # Regression in GCC 9/10, spams so much in our variadic templates
+                # that we need to outright disable it.
+                common_warnings += ["-Wno-type-limits"]
+            if cc_version_major >= 12:  # False positives in our error macros, see GH-58747.
+                common_warnings += ["-Wno-return-type"]
+        elif using_clang(env) or using_emcc(env):
+            # We often implement `operator<` for structs of pointers as a requirement
+            # for putting them in `Set` or `Map`. We don't mind about unreliable ordering.
+            common_warnings += ["-Wno-ordered-compare-function-pointers"]
+
+        if env["warnings"] == "extra":
+            env.Append(CCFLAGS=["-Wall", "-Wextra", "-Wwrite-strings", "-Wno-unused-parameter"] + common_warnings)
+            env.Append(CXXFLAGS=["-Wctor-dtor-privacy", "-Wnon-virtual-dtor"])
+            if using_gcc(env):
+                env.Append(
+                    CCFLAGS=[
+                        "-Walloc-zero",
+                        "-Wduplicated-branches",
+                        "-Wduplicated-cond",
+                        "-Wstringop-overflow=4",
+                    ]
+                )
+                env.Append(CXXFLAGS=["-Wplacement-new=1"])
+                # Need to fix a warning with AudioServer lambdas before enabling.
+                # if cc_version_major != 9:  # GCC 9 had a regression (GH-36325).
+                #    env.Append(CXXFLAGS=["-Wnoexcept"])
+                if cc_version_major >= 9:
+                    env.Append(CCFLAGS=["-Wattribute-alias=2"])
+                if cc_version_major >= 11:  # Broke on MethodBind templates before GCC 11.
+                    env.Append(CCFLAGS=["-Wlogical-op"])
+            elif using_clang(env) or using_emcc(env):
+                env.Append(CCFLAGS=["-Wimplicit-fallthrough"])
+        elif env["warnings"] == "all":
+            env.Append(CCFLAGS=["-Wall"] + common_warnings)
+        elif env["warnings"] == "moderate":
+            env.Append(CCFLAGS=["-Wall", "-Wno-unused"] + common_warnings)
+        else:  # 'no'
+            env.Append(CCFLAGS=["-w"])
+
+        if env["werror"]:
+            env.Append(CCFLAGS=["-Werror"])

tools/windows.py

@@ -32,7 +32,6 @@ def generate(env):
 
         env.Append(CPPDEFINES=["TYPED_METHOD_BIND", "NOMINMAX"])
         env.Append(CCFLAGS=["/utf-8"])
-        env.Append(LINKFLAGS=["/WX"])
 
         if env["use_clang_cl"]:
             env["CC"] = "clang-cl"