Add magic to foundation.h to provide alignof everywhere

livecodefraser · livecodefraser · commit f3b90120efe0 · 2016-10-18T10:59:09.000+01:00
C++11 added alignof(x) to return the alignment of a type. Not all of our
compilers support this but they do all have equivalents. Lots of ifdef
magic has been added to foundation.h to support this.
diff --git a/libfoundation/include/foundation.h b/libfoundation/include/foundation.h
@@ -413,6 +413,40 @@ along with LiveCode.  If not see <http://www.gnu.org/licenses/>.  */
 #  define MC_DLLEXPORT_DEF __attribute__((__visibility__("default"), __used__))
 #endif
 
+////////////////////////////////////////////////////////////////////////////////
+//
+//  C++ COMPATIBILITY
+//
+
+#ifndef __has_feature
+#  define __has_feature(x)	0
+#endif
+#ifndef __has_extension
+#  define __has_extension(x) __has_feature(x)
+#endif
+
+// Ensure we have alignof(...) available
+#if defined(__cplusplus) && !__has_feature(cxx_alignof)
+// Testing __cplusplus isn't sufficient as some compilers changed the value before being fully-conforming
+#  if defined(__clang__)
+     // No need for a version check; Clang supports __has_feature as a built-in
+     // so if we get here, it isn't supported
+#    define alignof(x)      __alignof__(x)
+#  elif defined(__GNUC__)
+     // GCC added C++11 alignof(x) in GCC 4.8
+#    if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR < 8)
+#      define alignof(x)    __alignof__(x)
+#    endif
+#  elif defined(_MSC_VER)
+     // MSVC added C++11 alignof(x) in Visual Studio 2012 (compiler version 11.0, _MSC_VER 1700)
+#    if (_MSC_VER < 1700)
+#      define alignof(x)    __alignof(x)
+#    endif
+#  else
+#    error Don't know how to get alignof(x) on this compiler
+#  endif
+#endif
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 //  FIXED WIDTH INTEGER TYPES
diff --git a/libscript/src/script-execute.cpp b/libscript/src/script-execute.cpp
@@ -116,7 +116,7 @@ class MCScriptForeignInvocation
 	{
 		if (m_argument_count == kMaxArguments ||
 			!Allocate(sizeof(void *),
-					  __alignof__(void *),
+					  alignof(void *),
 					  m_argument_values[m_argument_count]))
 		{
 			return MCErrorThrowOutOfMemory();
@@ -208,13 +208,13 @@ __MCScriptComputeSlotAttributes(const MCResolvedTypeInfo& p_slot_type,
 		MCHandlerTypeInfoIsForeign(p_slot_type.type))
 	{
 		r_slot_size = sizeof(void*);
-		r_slot_align = __alignof__(void *);
+		r_slot_align = alignof(void*);
 		r_slot_drop = nil;
 		return;
 	}
-	
+
 	r_slot_size = sizeof(void*);
-	r_slot_align = __alignof__(void*);
+	r_slot_align = alignof(void*);
 	r_slot_drop = __MCScriptDropValueRef;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -116,7 +116,7 @@ class MCScriptForeignInvocation`
`116`	`116`	`{`
`117`	`117`	`if (m_argument_count == kMaxArguments \|\|`
`118`	`118`	`!Allocate(sizeof(void *),`
`119`		`- __alignof__(void *),`
	`119`	`+ alignof(void *),`
`120`	`120`	`m_argument_values[m_argument_count]))`
`121`	`121`	`{`
`122`	`122`	`return MCErrorThrowOutOfMemory();`
`@@ -208,13 +208,13 @@ __MCScriptComputeSlotAttributes(const MCResolvedTypeInfo& p_slot_type,`
`208`	`208`	`MCHandlerTypeInfoIsForeign(p_slot_type.type))`
`209`	`209`	`{`
`210`	`210`	`r_slot_size = sizeof(void*);`
`211`		`- r_slot_align = __alignof__(void *);`
	`211`	`+ r_slot_align = alignof(void*);`
`212`	`212`	`r_slot_drop = nil;`
`213`	`213`	`return;`
`214`	`214`	`}`
`215`		`-`
	`215`	`+`
`216`	`216`	`r_slot_size = sizeof(void*);`
`217`		`- r_slot_align = __alignof__(void*);`
	`217`	`+ r_slot_align = alignof(void*);`
`218`	`218`	`r_slot_drop = __MCScriptDropValueRef;`
`219`	`219`	`}`
`220`	`220`