gccrs: Add rust_debug_fmt

This should allow the use of gcc diagnostic format specifiers in debug
diagnostics, in exchange for stricter diagnostic quality checks.

gcc/rust/ChangeLog:

	* rust-diagnostics.cc (rust_debug_fmt_at): New function
	definition.
	* rust-diagnostics.h (rust_debug_fmt): New function-like macro
	definition.
	(rust_debug_fmt_at): New function declaration.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

Author: powerboat9

gcc/rust/rust-diagnostics.cc

@@ -420,6 +420,19 @@ rust_debug_loc (const location_t location, const char *fmt, ...)
   rust_be_inform (location, rval);
 }
 
+void
+rust_debug_fmt_at (const location_t location, const char *fmt, ...)
+{
+  if (!rust_be_debug_p ())
+    return;
+
+  va_list ap;
+
+  va_start (ap, fmt);
+  rust_be_inform (location, expand_message (fmt, ap));
+  va_end (ap);
+}
+
 namespace Rust {
 
 /**

gcc/rust/rust-diagnostics.h

@@ -307,4 +307,10 @@ struct Error
 void rust_debug_loc (const location_t location, const char *fmt,
 		     ...) ATTRIBUTE_PRINTF_2;
 
+// like rust_debug, but has gcc diagnostic formatting
+#define rust_debug_fmt(...) rust_debug_fmt_at (UNDEF_LOCATION, __VA_ARGS__)
+
+void rust_debug_fmt_at (location_t location, const char *fmt, ...)
+  RUST_ATTRIBUTE_GCC_DIAG (2, 3);
+
 #endif // !defined(RUST_DIAGNOSTICS_H)