Use absl's wrappers around __has_attribute etc rather than polyfilling.

The goal is to reduce the surface area and size of port_def.inc, as a somewhat
magic textual header.
(Also #defining __reserved_names is a bit of a maintenance risk)

PiperOrigin-RevId: 572188636

src/google/protobuf/port_def.inc

@@ -30,6 +30,8 @@
 #error "port_def.inc included multiple times"
 #endif
 #define PROTOBUF_PORT_
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
 
 // The definitions in this file are intended to be portable across Clang,
 // GCC, and MSVC. Function-like macros are usable without an #ifdef guard.
@@ -65,42 +67,12 @@
 // - MSVC: https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-history
 //         https://docs.microsoft.com/en-us/visualstudio/releasenotes/vs2017-relnotes-history
 
-// Portable fallbacks for C++20 feature test macros:
-// https://en.cppreference.com/w/cpp/feature_test
-#ifndef __has_cpp_attribute
-#define __has_cpp_attribute(x) 0
-#define PROTOBUF_has_cpp_attribute_DEFINED_
-#endif
-
-// Portable fallback for Clang's __has_feature macro:
-// https://clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension
-#ifndef __has_feature
-#define __has_feature(x) 0
-#define PROTOBUF_has_feature_DEFINED_
-#endif
-
 // Portable fallback for Clang's __has_warning macro:
 #ifndef __has_warning
 #define __has_warning(x) 0
 #define PROTOBUF_has_warning_DEFINED_
 #endif
 
-// Portable fallbacks for the __has_attribute macro (GCC and Clang):
-// https://clang.llvm.org/docs/LanguageExtensions.html#has-attribute
-// https://gcc.gnu.org/onlinedocs/cpp/_005f_005fhas_005fattribute.html
-#ifndef __has_attribute
-#define __has_attribute(x) 0
-#define PROTOBUF_has_attribute_DEFINED_
-#endif
-
-// Portable fallback for __has_builtin (GCC and Clang):
-// https://clang.llvm.org/docs/LanguageExtensions.html#has-builtin
-// https://gcc.gnu.org/onlinedocs/cpp/_005f_005fhas_005fbuiltin.html
-#ifndef __has_builtin
-#define __has_builtin(x) 0
-#define PROTOBUF_has_builtin_DEFINED_
-#endif
-
 #ifdef ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #define PROTOBUF_POISON_MEMORY_REGION(p, n) ASAN_POISON_MEMORY_REGION(p, n)
@@ -121,23 +93,23 @@
 #ifdef PROTOBUF_BUILTIN_BSWAP64
 #error PROTOBUF_BUILTIN_BSWAP64 was previously defined
 #endif
-#if defined(__GNUC__) || __has_builtin(__builtin_bswap16)
+#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap16)
 #define PROTOBUF_BUILTIN_BSWAP16(x) __builtin_bswap16(x)
 #endif
-#if defined(__GNUC__) || __has_builtin(__builtin_bswap32)
+#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap32)
 #define PROTOBUF_BUILTIN_BSWAP32(x) __builtin_bswap32(x)
 #endif
-#if defined(__GNUC__) || __has_builtin(__builtin_bswap64)
+#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap64)
 #define PROTOBUF_BUILTIN_BSWAP64(x) __builtin_bswap64(x)
 #endif
 
 // Portable check for __builtin_mul_overflow.
-#if __has_builtin(__builtin_mul_overflow)
+#if ABSL_HAVE_BUILTIN(__builtin_mul_overflow)
 #define PROTOBUF_HAS_BUILTIN_MUL_OVERFLOW 1
 #endif
 
 // Portable check for gcc-style atomic built-ins
-#if __has_builtin(__atomic_load_n)
+#if ABSL_HAVE_BUILTIN(__atomic_load_n)
 #define PROTOBUF_BUILTIN_ATOMIC 1
 #endif
 
@@ -282,7 +254,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 // Use like:
 //   PROTOBUF_ALWAYS_INLINE_CALL res = SomeFunc(args...);
 #if defined(__clang__) && !defined(PROTOBUF_NO_INLINE_CALL) && \
-    __has_cpp_attribute(clang::always_inline)
+    ABSL_HAVE_CPP_ATTRIBUTE(clang::always_inline)
 #define PROTOBUF_ALWAYS_INLINE_CALL [[clang::always_inline]]
 #else
 #define PROTOBUF_ALWAYS_INLINE_CALL
@@ -321,7 +293,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_TAILCALL
 #error PROTOBUF_TAILCALL was previously defined
 #endif
-#if __has_cpp_attribute(clang::musttail) && !defined(__arm__) &&      \
+#if ABSL_HAVE_CPP_ATTRIBUTE(clang::musttail) && !defined(__arm__) &&  \
     !defined(_ARCH_PPC) && !defined(__wasm__) &&                      \
     !(defined(_MSC_VER) && defined(_M_IX86)) && !defined(__i386__)
 // Compilation fails on ARM32: b/195943306
@@ -338,7 +310,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_EXCLUSIVE_LOCKS_REQUIRED
 #error PROTOBUF_EXCLUSIVE_LOCKS_REQUIRED was previously defined
 #endif
-#if __has_attribute(exclusive_locks_required)
+#if ABSL_HAVE_ATTRIBUTE(exclusive_locks_required)
 #define PROTOBUF_EXCLUSIVE_LOCKS_REQUIRED(...) \
   __attribute__((exclusive_locks_required(__VA_ARGS__)))
 #else
@@ -348,7 +320,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_NO_THREAD_SAFETY_ANALYSIS
 #error PROTOBUF_NO_THREAD_SAFETY_ANALYSIS was previously defined
 #endif
-#if __has_attribute(no_thread_safety_analysis)
+#if ABSL_HAVE_ATTRIBUTE(no_thread_safety_analysis)
 #define PROTOBUF_NO_THREAD_SAFETY_ANALYSIS \
   __attribute__((no_thread_safety_analysis))
 #else
@@ -358,7 +330,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_GUARDED_BY
 #error PROTOBUF_GUARDED_BY was previously defined
 #endif
-#if __has_attribute(guarded_by)
+#if ABSL_HAVE_ATTRIBUTE(guarded_by)
 #define PROTOBUF_GUARDED_BY(x) __attribute__((guarded_by(x)))
 #else
 #define PROTOBUF_GUARDED_BY(x)
@@ -367,7 +339,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_LOCKS_EXCLUDED
 #error PROTOBUF_LOCKS_EXCLUDED was previously defined
 #endif
-#if __has_attribute(locks_excluded)
+#if ABSL_HAVE_ATTRIBUTE(locks_excluded)
 #define PROTOBUF_LOCKS_EXCLUDED(...) \
   __attribute__((locks_excluded(__VA_ARGS__)))
 #else
@@ -377,7 +349,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_COLD
 #error PROTOBUF_COLD was previously defined
 #endif
-#if __has_attribute(cold) || defined(__GNUC__)
+#if ABSL_HAVE_ATTRIBUTE(cold) || defined(__GNUC__)
 # define PROTOBUF_COLD __attribute__((cold))
 #else
 # define PROTOBUF_COLD
@@ -386,7 +358,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_SECTION_VARIABLE
 #error PROTOBUF_SECTION_VARIABLE was previously defined
 #endif
-#if (__has_attribute(section) || defined(__GNUC__)) && defined(__ELF__)
+#if (ABSL_HAVE_ATTRIBUTE(section) || defined(__GNUC__)) && defined(__ELF__)
 // Place a variable in the given ELF section.
 # define PROTOBUF_SECTION_VARIABLE(x) __attribute__((section(#x)))
 #else
@@ -413,7 +385,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_RETURNS_NONNULL
 #error PROTOBUF_RETURNS_NONNULL was previously defined
 #endif
-#if __has_attribute(returns_nonnull) || defined(__GNUC__)
+#if ABSL_HAVE_ATTRIBUTE(returns_nonnull) || defined(__GNUC__)
 #define PROTOBUF_RETURNS_NONNULL __attribute__((returns_nonnull))
 #else
 #define PROTOBUF_RETURNS_NONNULL
@@ -422,7 +394,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_ATTRIBUTE_REINITIALIZES
 #error PROTOBUF_ATTRIBUTE_REINITIALIZES was previously defined
 #endif
-#if __has_cpp_attribute(clang::reinitializes)
+#if ABSL_HAVE_CPP_ATTRIBUTE(clang::reinitializes)
 #define PROTOBUF_ATTRIBUTE_REINITIALIZES [[clang::reinitializes]]
 #else
 #define PROTOBUF_ATTRIBUTE_REINITIALIZES
@@ -441,7 +413,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #elif defined(__cpp_rtti)
 // https://en.cppreference.com/w/cpp/feature_test
 #define PROTOBUF_RTTI 1
-#elif __has_feature(cxx_rtti)
+#elif ABSL_HAVE_FEATURE(cxx_rtti)
 // https://clang.llvm.org/docs/LanguageExtensions.html#c-rtti
 #define PROTOBUF_RTTI 1
 #elif defined(__GXX_RTTI)
@@ -553,9 +525,9 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_NODISCARD
 #error PROTOBUF_NODISCARD was previously defined
 #endif
-#if __has_cpp_attribute(nodiscard) && PROTOBUF_CPLUSPLUS_MIN(201703L)
+#if ABSL_HAVE_CPP_ATTRIBUTE(nodiscard) && PROTOBUF_CPLUSPLUS_MIN(201703L)
 #define PROTOBUF_NODISCARD [[nodiscard]]
-#elif __has_attribute(warn_unused_result) || defined(__GNUC__)
+#elif ABSL_HAVE_ATTRIBUTE(warn_unused_result) || defined(__GNUC__)
 #define PROTOBUF_NODISCARD __attribute__((warn_unused_result))
 #else
 #define PROTOBUF_NODISCARD
@@ -611,9 +583,10 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_FALLTHROUGH_INTENDED
 #error PROTOBUF_FALLTHROUGH_INTENDED was previously defined
 #endif
-#if __has_cpp_attribute(fallthrough)
+#if ABSL_HAVE_CPP_ATTRIBUTE(fallthrough)
 #define PROTOBUF_FALLTHROUGH_INTENDED [[fallthrough]]
-#elif __has_feature(cxx_attributes) && __has_warning("-Wimplicit-fallthrough")
+#elif ABSL_HAVE_FEATURE(cxx_attributes) && \
+    __has_warning("-Wimplicit-fallthrough")
 #define PROTOBUF_FALLTHROUGH_INTENDED [[clang::fallthrough]]
 #elif defined(__GNUC__)
 #define PROTOBUF_FALLTHROUGH_INTENDED [[gnu::fallthrough]]
@@ -710,8 +683,8 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 // constant-initializing weak default instance pointers. Versions 12.0 and
 // higher seem to work, except that XCode 12.5.1 shows the error even though it
 // uses Clang 12.0.5.
-# elif !defined(__CYGWIN__) && !defined(__MINGW32__) && \
+#elif !defined(__CYGWIN__) && !defined(__MINGW32__) &&                 \
-    __has_cpp_attribute(clang::require_constant_initialization) && \
+    ABSL_HAVE_CPP_ATTRIBUTE(clang::require_constant_initialization) && \
     ((defined(__APPLE__) && PROTOBUF_CLANG_MIN(13, 0)) ||              \
      (!defined(__APPLE__) && PROTOBUF_CLANG_MIN(12, 0)))
 #  define PROTOBUF_CONSTINIT [[clang::require_constant_initialization]]
@@ -731,7 +704,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_ATTRIBUTE_NO_DESTROY
 #error PROTOBUF_ATTRIBUTE_NO_DESTROY was previously defined
 #endif
-#if __has_cpp_attribute(clang::no_destroy)
+#if ABSL_HAVE_CPP_ATTRIBUTE(clang::no_destroy)
 #define PROTOBUF_ATTRIBUTE_NO_DESTROY [[clang::no_destroy]]
 #else
 #define PROTOBUF_ATTRIBUTE_NO_DESTROY
@@ -746,7 +719,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_ATTRIBUTE_STANDALONE_DEBUG
 #error PROTOBUF_ATTRIBUTE_STANDALONE_DEBUG was previously defined
 #endif
-#if __has_cpp_attribute(clang::standalone_debug)
+#if ABSL_HAVE_CPP_ATTRIBUTE(clang::standalone_debug)
 #define PROTOBUF_ATTRIBUTE_STANDALONE_DEBUG [[clang::standalone_debug]]
 #else
 #define PROTOBUF_ATTRIBUTE_STANDALONE_DEBUG
@@ -788,10 +761,8 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_ATTRIBUTE_WEAK
 #error PROTOBUF_ATTRIBUTE_WEAK was previously defined
 #endif
-#if __has_attribute(weak) && \
+#if ABSL_HAVE_ATTRIBUTE(weak) && !defined(__APPLE__) && \
-    !defined(__APPLE__) && \
+    (!defined(_WIN32) || __clang_major__ < 9) && !defined(__MINGW32__)
-    (!defined(_WIN32) || __clang_major__ < 9) && \
-    !defined(__MINGW32__)
 #define PROTOBUF_ATTRIBUTE_WEAK __attribute__((weak))
 #define PROTOBUF_HAVE_ATTRIBUTE_WEAK 1
 #else
@@ -810,13 +781,13 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #error PROTOBUF_TSAN was previously defined
 #endif
 #if defined(__clang__)
-#  if __has_feature(address_sanitizer)
+#if ABSL_HAVE_FEATURE(address_sanitizer)
 #    define PROTOBUF_ASAN 1
 #  endif
-#  if __has_feature(thread_sanitizer)
+#if ABSL_HAVE_FEATURE(thread_sanitizer)
 #    define PROTOBUF_TSAN 1
 #  endif
-#  if __has_feature(memory_sanitizer)
+#if ABSL_HAVE_FEATURE(memory_sanitizer)
 #    define PROTOBUF_MSAN 1
 #  endif
 #elif defined(__GNUC__)
@@ -905,10 +876,10 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_UNUSED
 #error PROTOBUF_UNUSED was previously defined
 #endif
-#if __has_cpp_attribute(maybe_unused) || \
+#if ABSL_HAVE_CPP_ATTRIBUTE(maybe_unused) || \
     (PROTOBUF_MSC_VER_MIN(1911) && PROTOBUF_CPLUSPLUS_MIN(201703L))
 #define PROTOBUF_UNUSED [[maybe_unused]]
-#elif __has_attribute(unused) || defined(__GNUC__)
+#elif ABSL_HAVE_ATTRIBUTE(unused) || defined(__GNUC__)
 #define PROTOBUF_UNUSED __attribute__((__unused__))
 #else
 #define PROTOBUF_UNUSED
@@ -922,7 +893,7 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #ifdef PROTOBUF_BUILTIN_CONSTANT_P
 #error PROTOBUF_BUILTIN_CONSTANT_P was previously defined
 #endif
-#if __has_builtin(__builtin_constant_p)
+#if ABSL_HAVE_BUILTIN(__builtin_constant_p)
 #define PROTOBUF_BUILTIN_CONSTANT_P(x) __builtin_constant_p(x)
 #else
 #define PROTOBUF_BUILTIN_CONSTANT_P(x) false
@@ -1172,7 +1143,7 @@ PROTOBUF_EXPORT void protobuf_assumption_failed(const char *pred,
 #ifdef PROTOBUF_ASSUME
 #error PROTOBUF_ASSUME was previously defined
 #endif
-#if __has_builtin(__builtin_assume)
+#if ABSL_HAVE_BUILTIN(__builtin_assume)
 #ifdef NDEBUG
 #define PROTOBUF_ASSUME(pred) __builtin_assume(pred)
 #else  // NDEBUG
@@ -1196,23 +1167,7 @@ PROTOBUF_EXPORT void protobuf_assumption_failed(const char *pred,
 // We don't want code outside port_def doing complex testing, so
 // remove our portable condition test macros to nudge folks away from
 // using it themselves.
-#ifdef PROTOBUF_has_cpp_attribute_DEFINED_
-#  undef __has_cpp_attribute
-#  undef PROTOBUF_has_cpp_attribute_DEFINED_
-#endif
-#ifdef PROTOBUF_has_feature_DEFINED_
-#  undef __has_feature
-#  undef PROTOBUF_has_feature_DEFINED_
-#endif
 #ifdef PROTOBUF_has_warning_DEFINED_
 #  undef __has_warning
 #  undef PROTOBUF_has_warning_DEFINED_
 #endif
-#ifdef PROTOBUF_has_attribute_DEFINED_
-#  undef __has_attribute
-#  undef PROTOBUF_has_attribute_DEFINED_
-#endif
-#ifdef PROTOBUF_has_builtin_DEFINED_
-#  undef __has_builtin
-#  undef PROTOBUF_has_builtin_DEFINED_
-#endif