Core: Bump C++ Standard to C++20

Author: Repiteo

.github/workflows/linux_builds.yml

@@ -11,15 +11,14 @@ env:
   GODOT_CPP_BRANCH: 4.4
   DOTNET_NOLOGO: true
   DOTNET_CLI_TELEMETRY_OPTOUT: true
-  ASAN_OPTIONS: color=always:print_suppressions=1:suppressions=${{ github.workspace }}/misc/error_suppressions/asan.txt
+  ASAN_OPTIONS: color=always:print_suppressions=1:suppressions=${{ github.workspace }}/misc/error_suppressions/asan.txt:alloc_dealloc_mismatch=0
   LSAN_OPTIONS: color=always:print_suppressions=1:suppressions=${{ github.workspace }}/misc/error_suppressions/lsan.txt
   TSAN_OPTIONS: color=always:print_suppressions=1:suppressions=${{ github.workspace }}/misc/error_suppressions/tsan.txt
   UBSAN_OPTIONS: color=always:print_suppressions=1:suppressions=${{ github.workspace }}/misc/error_suppressions/ubsan.txt
 
 jobs:
   build-linux:
-    # Stay one LTS before latest to increase portability of Linux artifacts.
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     name: ${{ matrix.name }}
     timeout-minutes: 120
     strategy:

SConstruct

@@ -665,16 +665,16 @@ cc_version_metadata1 = cc_version["metadata1"]
 
 if cc_version_major == -1:
     print_warning(
-        "Couldn't detect compiler version, skipping version checks. "
-        "Build may fail if the compiler doesn't support C++17 fully."
+        "Couldn't detect compiler version, skipping version checks. Build may "
+        "fail if the compiler doesn't support C++20 fully."
     )
 elif methods.using_gcc(env):
-    if cc_version_major < 9:
+    if cc_version_major < 11:
         print_error(
-            "Detected GCC version older than 9, which does not fully support "
-            "C++17, or has bugs when compiling Godot. Supported versions are 9 "
-            "and later. Use a newer GCC version, or Clang 6 or later by passing "
-            '"use_llvm=yes" to the SCons command line.'
+            "Detected GCC version older than 11, which does not fully support "
+            "C++20. Supported versions are GCC 11 and later. Use a newer GCC "
+            'version, or Clang 16 or later by passing "use_llvm=yes" to the '
+            "SCons command line."
         )
         Exit(255)
     elif cc_version_metadata1 == "win32":
@@ -689,47 +689,33 @@ elif methods.using_clang(env):
     # Apple LLVM versions differ from upstream LLVM version \o/, compare
     # in https://en.wikipedia.org/wiki/Xcode#Toolchain_versions
     if methods.is_apple_clang(env):
-        if cc_version_major < 10:
+        if cc_version_major < 15:
             print_error(
-                "Detected Apple Clang version older than 10, which does not fully "
-                "support C++17. Supported versions are Apple Clang 10 and later."
+                "Detected Apple Clang version older than 15, which does not fully "
+                "support C++20. Supported versions are Apple Clang 15 and later."
             )
             Exit(255)
-        elif env["debug_paths_relative"] and cc_version_major < 12:
-            print_warning(
-                "Apple Clang < 12 doesn't support -ffile-prefix-map, disabling `debug_paths_relative` option."
-            )
-            env["debug_paths_relative"] = False
     else:
-        if cc_version_major < 6:
+        if cc_version_major < 16:
             print_error(
-                "Detected Clang version older than 6, which does not fully support "
-                "C++17. Supported versions are Clang 6 and later."
+                "Detected Clang version older than 16, which does not fully support "
+                "C++20. Supported versions are Clang 16 and later."
             )
             Exit(255)
-        elif env["debug_paths_relative"] and cc_version_major < 10:
-            print_warning("Clang < 10 doesn't support -ffile-prefix-map, disabling `debug_paths_relative` option.")
-            env["debug_paths_relative"] = False
 
 elif env.msvc:
     # Ensure latest minor builds of Visual Studio 2017/2019.
     # https://github.com/godotengine/godot/pull/94995#issuecomment-2336464574
-    if cc_version_major == 16 and cc_version_minor < 11:
-        print_error(
-            "Detected Visual Studio 2019 version older than 16.11, which has bugs "
-            "when compiling Godot. Use a newer VS2019 version, or VS2022."
-        )
-        Exit(255)
-    if cc_version_major == 15 and cc_version_minor < 9:
+    if cc_version_major < 16:
         print_error(
-            "Detected Visual Studio 2017 version older than 15.9, which has bugs "
-            "when compiling Godot. Use a newer VS2017 version, or VS2019/VS2022."
+            "Detected Visual Studio version older than 2019, which does not fully "
+            "support C++20. Supported versions are Visual Studio 2019 and later."
         )
         Exit(255)
-    if cc_version_major < 15:
+    elif cc_version_major == 16 and cc_version_minor < 11:
         print_error(
-            "Detected Visual Studio 2015 or earlier, which is unsupported in Godot. "
-            "Supported versions are Visual Studio 2017 and later."
+            "Detected Visual Studio 2019 version older than 16.11, which has bugs "
+            "when compiling Godot. Use a newer VS2019 version, or VS2022."
         )
         Exit(255)
 
@@ -840,22 +826,17 @@ if env["lto"] != "none":
     print("Using LTO: " + env["lto"])
 
 # Set our C and C++ standard requirements.
-# C++17 is required as we need guaranteed copy elision as per GH-36436.
-# Prepending to make it possible to override.
 # This needs to come after `configure`, otherwise we don't have env.msvc.
 if not env.msvc:
     # Specifying GNU extensions support explicitly, which are supported by
-    # both GCC and Clang. Both currently default to gnu17 and gnu++17.
+    # both GCC and Clang. Both currently default to gnu17 and gnu++20.
     env.Prepend(CFLAGS=["-std=gnu17"])
-    env.Prepend(CXXFLAGS=["-std=gnu++17"])
+    env.Prepend(CXXFLAGS=["-std=gnu++20"])
 else:
     # MSVC started offering C standard support with Visual Studio 2019 16.8, which covers all
-    # of our supported VS2019 & VS2022 versions; VS2017 will only pass the C++ standard.
-    env.Prepend(CXXFLAGS=["/std:c++17"])
-    if cc_version_major < 16:
-        print_warning("Visual Studio 2017 cannot specify a C-Standard.")
-    else:
-        env.Prepend(CFLAGS=["/std:c17"])
+    # of our supported VS2019 & VS2022 versions.
+    env.Prepend(CFLAGS=["/std:c17"])
+    env.Prepend(CXXFLAGS=["/std:c++20"])
     # MSVC is non-conforming with the C++ standard by default, so we enable more conformance.
     # Note that this is still not complete conformance, as certain Windows-related headers
     # don't compile under complete conformance.
@@ -913,22 +894,15 @@ if env.msvc and not methods.using_clang(env):  # MSVC
 else:  # GCC, Clang
     common_warnings = []
     if methods.using_gcc(env):
-        common_warnings += ["-Wshadow", "-Wno-misleading-indentation"]
-        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"]
+        common_warnings += ["-Wshadow", "-Wno-misleading-indentation", "-Wenum-conversion"]
         if cc_version_major == 12:
             # Regression in GCC 12, false positives in our error macros, see GH-58747.
             common_warnings += ["-Wno-return-type"]
-        if cc_version_major >= 11:
-            common_warnings += ["-Wenum-conversion"]
     elif methods.using_clang(env) or methods.using_emcc(env):
-        common_warnings += ["-Wshadow-field-in-constructor", "-Wshadow-uncaptured-local"]
+        common_warnings += ["-Wshadow-field-in-constructor", "-Wshadow-uncaptured-local", "-Wenum-conversion"]
         # 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"]
-        common_warnings += ["-Wenum-conversion"]
 
     # clang-cl will interpret `-Wall` as `-Weverything`, workaround with compatibility cast.
     env["WARNLEVEL"] = "-Wall" if not env.msvc else "-W3"
@@ -940,19 +914,14 @@ else:  # GCC, Clang
             env.AppendUnique(
                 CCFLAGS=[
                     "-Walloc-zero",
+                    "-Wattribute-alias=2",
                     "-Wduplicated-branches",
                     "-Wduplicated-cond",
+                    "-Wlogical-op",
                     "-Wstringop-overflow=4",
                 ]
             )
             env.AppendUnique(CXXFLAGS=["-Wplacement-new=1", "-Wvirtual-inheritance"])
-            # 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.AppendUnique(CCFLAGS=["-Wattribute-alias=2"])
-            if cc_version_major >= 11:  # Broke on MethodBind templates before GCC 11.
-                env.AppendUnique(CCFLAGS=["-Wlogical-op"])
         elif methods.using_clang(env) or methods.using_emcc(env):
             env.AppendUnique(CCFLAGS=["-Wimplicit-fallthrough"])
     elif env["warnings"] == "all":
@@ -968,8 +937,6 @@ else:  # GCC, Clang
 # Configure external includes.
 if env.msvc:
     if not methods.using_clang(env):
-        if cc_version_major < 16 or (cc_version_major == 16 and cc_version_minor < 10):
-            env.AppendUnique(CCFLAGS=["/experimental:external"])
         env.AppendUnique(CCFLAGS=["/external:anglebrackets"])
     env.AppendUnique(CCFLAGS=["/external:W0"])
     env["EXTINCPREFIX"] = "/external:I"

core/io/ip_address.h

@@ -63,21 +63,7 @@ struct [[nodiscard]] IPAddress {
 		}
 		return true;
 	}
-
-	bool operator!=(const IPAddress &p_ip) const {
-		if (p_ip.valid != valid) {
-			return true;
-		}
-		if (!valid) {
-			return true;
-		}
-		for (int i = 0; i < 4; i++) {
-			if (field32[i] != p_ip.field32[i]) {
-				return true;
-			}
-		}
-		return false;
-	}
+	bool operator==(const String &p_ip) const { return operator==(IPAddress(p_ip)); }
 
 	void clear();
 	bool is_wildcard() const { return wildcard; }

core/math/aabb.h

@@ -61,9 +61,6 @@ struct [[nodiscard]] AABB {
 	constexpr bool operator==(const AABB &p_rval) const {
 		return position == p_rval.position && size == p_rval.size;
 	}
-	constexpr bool operator!=(const AABB &p_rval) const {
-		return position != p_rval.position || size != p_rval.size;
-	}
 
 	bool is_equal_approx(const AABB &p_aabb) const;
 	bool is_same(const AABB &p_aabb) const;

core/math/basis.h

@@ -124,7 +124,6 @@ struct [[nodiscard]] Basis {
 	bool is_finite() const;
 
 	constexpr bool operator==(const Basis &p_matrix) const;
-	constexpr bool operator!=(const Basis &p_matrix) const;
 
 	_FORCE_INLINE_ Vector3 xform(const Vector3 &p_vector) const;
 	_FORCE_INLINE_ Vector3 xform_inv(const Vector3 &p_vector) const;
@@ -259,10 +258,6 @@ constexpr bool Basis::operator==(const Basis &p_matrix) const {
 	return true;
 }
 
-constexpr bool Basis::operator!=(const Basis &p_matrix) const {
-	return (!(*this == p_matrix));
-}
-
 _FORCE_INLINE_ void Basis::operator*=(const Basis &p_matrix) {
 	set(
 			p_matrix.tdotx(rows[0]), p_matrix.tdoty(rows[0]), p_matrix.tdotz(rows[0]),

core/math/bvh_abb.h

@@ -59,7 +59,6 @@ struct BVH_ABB {
 	POINT neg_max;
 
 	bool operator==(const BVH_ABB &o) const { return (min == o.min) && (neg_max == o.neg_max); }
-	bool operator!=(const BVH_ABB &o) const { return (*this == o) == false; }
 
 	void set(const POINT &_min, const POINT &_max) {
 		min = _min;

core/math/bvh_tree.h

@@ -101,7 +101,6 @@ struct BVHHandle {
 	void set_id(uint32_t p_id) { _data = p_id; }
 
 	bool operator==(const BVHHandle &p_h) const { return _data == p_h._data; }
-	bool operator!=(const BVHHandle &p_h) const { return (*this == p_h) == false; }
 };
 
 // helper class to make iterative versions of recursive functions

core/math/color.h

@@ -74,9 +74,6 @@ struct [[nodiscard]] Color {
 	constexpr bool operator==(const Color &p_color) const {
 		return (r == p_color.r && g == p_color.g && b == p_color.b && a == p_color.a);
 	}
-	constexpr bool operator!=(const Color &p_color) const {
-		return (r != p_color.r || g != p_color.g || b != p_color.b || a != p_color.a);
-	}
 
 	constexpr Color operator+(const Color &p_color) const;
 	constexpr void operator+=(const Color &p_color);

core/math/convex_hull.cpp

@@ -136,10 +136,6 @@ class ConvexHullInternal {
 			return (x == b.x) && (y == b.y) && (z == b.z);
 		}
 
-		bool operator!=(const Point32 &b) const {
-			return (x != b.x) || (y != b.y) || (z != b.z);
-		}
-
 		bool is_zero() {
 			return (x == 0) && (y == 0) && (z == 0);
 		}

core/math/plane.h

@@ -77,7 +77,6 @@ struct [[nodiscard]] Plane {
 	bool is_finite() const;
 
 	constexpr bool operator==(const Plane &p_plane) const;
-	constexpr bool operator!=(const Plane &p_plane) const;
 	explicit operator String() const;
 
 	Plane() = default;
@@ -129,9 +128,5 @@ constexpr bool Plane::operator==(const Plane &p_plane) const {
 	return normal == p_plane.normal && d == p_plane.d;
 }
 
-constexpr bool Plane::operator!=(const Plane &p_plane) const {
-	return normal != p_plane.normal || d != p_plane.d;
-}
-
 template <>
 struct is_zero_constructible<Plane> : std::true_type {};