Allow disabling use of __builtin_constant_p in internal macros

Turns out that even in GCC, the expression in `__builtin_cosntant_p`
can end up evaluated and side-effects executed. To allow users to
work around this bug, I added a configuration option to disable its
use in internal macros.

Related to #2925

2 files changed, 48 insertions, 31 deletions

diff --git a/src/catch2/catch_user_config.hpp.in b/src/catch2/catch_user_config.hpp.in
index 10d61937..3acda688 100644
--- a/src/catch2/catch_user_config.hpp.in
+++ b/src/catch2/catch_user_config.hpp.in
@@ -178,6 +178,15 @@
 #endif
 
 
+#cmakedefine CATCH_CONFIG_USE_BUILTIN_CONSTANT_P
+#cmakedefine CATCH_CONFIG_NO_USE_BUILTIN_CONSTANT_P
+
+#if defined( CATCH_CONFIG_USE_BUILTIN_CONSTANT_P ) && \
+    defined( CATCH_CONFIG_NO_USE_BUILTIN_CONSTANT_P )
+#    error Cannot force USE_BUILTIN_CONSTANT_P to both ON and OFF
+#endif
+
+
 // ------
 // Simple toggle defines
 // their value is never used and they cannot be overridden
diff --git a/src/catch2/internal/catch_compiler_capabilities.hpp b/src/catch2/internal/catch_compiler_capabilities.hpp
index 7f09da51..d544b00c 100644
--- a/src/catch2/internal/catch_compiler_capabilities.hpp
+++ b/src/catch2/internal/catch_compiler_capabilities.hpp
@@ -62,7 +62,7 @@
 #    define CATCH_INTERNAL_SUPPRESS_SHADOW_WARNINGS \
          _Pragma( "GCC diagnostic ignored \"-Wshadow\"" )
 
-#    define CATCH_INTERNAL_IGNORE_BUT_WARN(...) (void)__builtin_constant_p(__VA_ARGS__)
+#    define CATCH_INTERNAL_CONFIG_USE_BUILTIN_CONSTANT_P
 
 #endif
 
@@ -86,35 +86,13 @@
 // clang-cl defines _MSC_VER as well as __clang__, which could cause the
 // start/stop internal suppression macros to be double defined.
 #if defined(__clang__) && !defined(_MSC_VER)
-
+#    define CATCH_INTERNAL_CONFIG_USE_BUILTIN_CONSTANT_P
 #    define CATCH_INTERNAL_START_WARNINGS_SUPPRESSION _Pragma( "clang diagnostic push" )
 #    define CATCH_INTERNAL_STOP_WARNINGS_SUPPRESSION  _Pragma( "clang diagnostic pop" )
-
 #endif // __clang__ && !_MSC_VER
 
 #if defined(__clang__)
 
-// As of this writing, IBM XL's implementation of __builtin_constant_p has a bug
-// which results in calls to destructors being emitted for each temporary,
-// without a matching initialization. In practice, this can result in something
-// like `std::string::~string` being called on an uninitialized value.
-//
-// For example, this code will likely segfault under IBM XL:
-// ```
-// REQUIRE(std::string("12") + "34" == "1234")
-// ```
-//
-// Similarly, NVHPC's implementation of `__builtin_constant_p` has a bug which
-// results in calls to the immediately evaluated lambda expressions to be
-// reported as unevaluated lambdas.
-// https://developer.nvidia.com/nvidia_bug/3321845.
-//
-// Therefore, `CATCH_INTERNAL_IGNORE_BUT_WARN` is not implemented.
-#  if !defined(__ibmxl__) && !defined(__CUDACC__) && !defined( __NVCOMPILER )
-#    define CATCH_INTERNAL_IGNORE_BUT_WARN(...) (void)__builtin_constant_p(__VA_ARGS__) /* NOLINT(cppcoreguidelines-pro-type-vararg, hicpp-vararg) */
-#  endif
-
-
 #    define CATCH_INTERNAL_SUPPRESS_GLOBALS_WARNINGS \
          _Pragma( "clang diagnostic ignored \"-Wexit-time-destructors\"" ) \
          _Pragma( "clang diagnostic ignored \"-Wglobal-constructors\"")
@@ -139,6 +117,27 @@
 
 #endif // __clang__
 
+// As of this writing, IBM XL's implementation of __builtin_constant_p has a bug
+// which results in calls to destructors being emitted for each temporary,
+// without a matching initialization. In practice, this can result in something
+// like `std::string::~string` being called on an uninitialized value.
+//
+// For example, this code will likely segfault under IBM XL:
+// ```
+// REQUIRE(std::string("12") + "34" == "1234")
+// ```
+//
+// Similarly, NVHPC's implementation of `__builtin_constant_p` has a bug which
+// results in calls to the immediately evaluated lambda expressions to be
+// reported as unevaluated lambdas.
+// https://developer.nvidia.com/nvidia_bug/3321845.
+//
+// Therefore, `CATCH_INTERNAL_IGNORE_BUT_WARN` is not implemented.
+#if defined( __ibmxl__ ) || defined( __CUDACC__ ) || defined( __NVCOMPILER )
+#    define CATCH_INTERNAL_CONFIG_NO_USE_BUILTIN_CONSTANT_P
+#endif
+
+
 
 ////////////////////////////////////////////////////////////////////////////////
 // We know some environments not to support full POSIX signals
@@ -362,6 +361,22 @@
 #endif
 
 
+// The goal of this macro is to avoid evaluation of the arguments, but
+// still have the compiler warn on problems inside...
+#if defined( CATCH_INTERNAL_CONFIG_USE_BUILTIN_CONSTANT_P ) && \
+    !defined( CATCH_INTERNAL_CONFIG_NO_USE_BUILTIN_CONSTANT_P ) && !defined(CATCH_CONFIG_USE_BUILTIN_CONSTANT_P)
+#define CATCH_CONFIG_USE_BUILTIN_CONSTANT_P
+#endif
+
+#if defined( CATCH_CONFIG_USE_BUILTIN_CONSTANT_P ) && \
+    !defined( CATCH_CONFIG_NO_USE_BUILTIN_CONSTANT_P )
+#    define CATCH_INTERNAL_IGNORE_BUT_WARN( ... )                                              \
+        (void)__builtin_constant_p( __VA_ARGS__ ) /* NOLINT(cppcoreguidelines-pro-type-vararg, \
+                                                     hicpp-vararg) */
+#else
+#    define CATCH_INTERNAL_IGNORE_BUT_WARN( ... )
+#endif
+
 // Even if we do not think the compiler has that warning, we still have
 // to provide a macro that can be used by the code.
 #if !defined(CATCH_INTERNAL_START_WARNINGS_SUPPRESSION)
@@ -398,13 +413,6 @@
 #    define CATCH_INTERNAL_SUPPRESS_SHADOW_WARNINGS
 #endif
 
-
-// The goal of this macro is to avoid evaluation of the arguments, but
-// still have the compiler warn on problems inside...
-#if !defined(CATCH_INTERNAL_IGNORE_BUT_WARN)
-#   define CATCH_INTERNAL_IGNORE_BUT_WARN(...)
-#endif
-
 #if defined(__APPLE__) && defined(__apple_build_version__) && (__clang_major__ < 10)
 #   undef CATCH_INTERNAL_SUPPRESS_UNUSED_TEMPLATE_WARNINGS
 #elif defined(__clang__) && (__clang_major__ < 5)