Add format checking attributes on printf-like functions (#2570)

* Add format checking attributes on printf-like functions

* Don't use printf format attributes on msvc

Where they are not supported

3 files changed, 11 insertions, 0 deletions

diff --git a/source/core/slang-common.h b/source/core/slang-common.h
index 7fddb067e..cd1490a20 100644
--- a/source/core/slang-common.h
+++ b/source/core/slang-common.h
@@ -120,6 +120,12 @@ template<typename T> void slang_use_obj(T&) {}
 #endif
 #endif
 
+#if defined(_MSC_VER)
+#   define SLANG_ATTR_PRINTF(string_index, varargs_index)
+#else
+#   define SLANG_ATTR_PRINTF(string_index, varargs_index) __attribute__((format(printf, string_index, varargs_index)))
+#endif
+
 #ifndef SLANG_RT_API
 #define SLANG_RT_API
 #endif
diff --git a/source/core/slang-secure-crt.h b/source/core/slang-secure-crt.h
index 991fe939e..b6f6671dd 100644
--- a/source/core/slang-secure-crt.h
+++ b/source/core/slang-secure-crt.h
@@ -47,6 +47,7 @@ inline size_t strnlen_s(const char * str, size_t numberOfElements)
 #endif
 }
 
+__attribute__((format(printf, 3, 4)))
 inline int sprintf_s(char * buffer, size_t sizeOfBuffer, const char * format, ...)
 {
 	va_list argptr;
@@ -56,6 +57,9 @@ inline int sprintf_s(char * buffer, size_t sizeOfBuffer, const char * format, ..
 	return rs;
 }
 
+// A patch was submitted to GCC wchar_t support in 2001, so I'm sure we can
+// enable this any day now...
+// __attribute__((format(wprintf, 3, 4)))
 inline int swprintf_s(wchar_t * buffer, size_t sizeOfBuffer, const wchar_t * format, ...)
 {
 	va_list argptr;
diff --git a/source/core/slang-writer.h b/source/core/slang-writer.h
index ccdcb3747..2a86af629 100644
--- a/source/core/slang-writer.h
+++ b/source/core/slang-writer.h
@@ -16,6 +16,7 @@ namespace Slang
 class WriterHelper
 {
 public:
+    SLANG_ATTR_PRINTF(2, 3)
     SlangResult print(const char* format, ...);
     SlangResult put(const char* text);
     SlangResult put(const UnownedStringSlice& text);