Add struct version to DownstreamCompiler::CompileOptions interface (#2692)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Add versioning to CompileOptions for DownstreamCompiler so we can add new options without breaking binary interface.

* Use builtin offset of directly.

1 files changed, 6 insertions, 3 deletions

diff --git a/slang.h b/slang.h
index d281cea85..ac097fbde 100644
--- a/slang.h
+++ b/slang.h
@@ -238,11 +238,14 @@ convention for interface methods.
 #   define SLANG_BREAKPOINT(id) __builtin_trap();
 #	define SLANG_ALIGN_OF(T)	__alignof__(T)
 
-// Use this macro instead of offsetof, because gcc produces warning if offsetof is used on a 
-// non POD type, even though it produces the correct result
-#   define SLANG_OFFSET_OF(T, ELEMENT) (size_t(&((T*)1)->ELEMENT) - 1)
+// Use the builtin directly so we don't need to have an include of stddef.h
+#   define SLANG_OFFSET_OF(T, ELEMENT) __builtin_offsetof(T, ELEMENT) 
 #endif // SLANG_GCC_FAMILY
 
+#ifndef SLANG_OFFSET_OF
+#   define SLANG_OFFSET_OF(T, ELEMENT) (size_t(&((T*)1)->ELEMENT) - 1)
+#endif
+
 // Microsoft VC specific
 #if SLANG_MICROSOFT_FAMILY
 #	define SLANG_NO_INLINE __declspec(noinline)