suppress GCC's -Wsuggest-attribute=format

I was not aware of this because I use clang these days.

compile.c

@@ -353,9 +353,9 @@ static void iseq_add_setlocal(rb_iseq_t *iseq, LINK_ANCHOR *const seq, const NOD
 
 /* error */
 #if CPDEBUG > 0
-NORETURN(static void append_compile_error(const rb_iseq_t *iseq, int line, const char *fmt, ...));
+RBIMPL_ATTR_NORETURN()
 #endif
-
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 3, 4)
 static void
 append_compile_error(const rb_iseq_t *iseq, int line, const char *fmt, ...)
 {

error.c

@@ -108,6 +108,7 @@ err_position_0(char *buf, long len, const char *file, int line)
     }
 }
 
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 5, 0)
 static VALUE
 err_vcatf(VALUE str, const char *pre, const char *file, int line,
 	  const char *fmt, va_list args)
@@ -344,6 +345,7 @@ rb_write_warning_str(VALUE str)
     rb_warning_warn(rb_mWarning, str);
 }
 
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 4, 0)
 static VALUE
 warn_vsprintf(rb_encoding *enc, const char *file, int line, const char *fmt, va_list args)
 {
@@ -396,6 +398,7 @@ rb_category_compile_warn(rb_warning_category_t category, const char *file, int l
     rb_warn_category(str, rb_warning_category_to_name(category));
 }
 
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 0)
 static VALUE
 warning_string(rb_encoding *enc, const char *fmt, va_list args)
 {
@@ -716,6 +719,7 @@ postscript_dump(FILE *out)
     bug_important_message(out, msg, msglen);
 }
 
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 0)
 static void
 bug_report_begin_valist(FILE *out, const char *fmt, va_list args)
 {
@@ -779,6 +783,7 @@ die(void)
     abort();
 }
 
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 1, 0)
 void
 rb_bug_without_die(const char *fmt, va_list args)
 {

include/ruby/missing.h

@@ -38,6 +38,7 @@
 #endif
 
 #include "ruby/internal/dllexport.h"
+#include "ruby/internal/attr/format.h"
 
 #ifndef M_PI
 # define M_PI 3.14159265358979323846
@@ -211,6 +212,7 @@ RUBY_EXTERN int ruby_close(int);
 #endif
 
 #ifndef HAVE_SETPROCTITLE
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 1, 2)
 RUBY_EXTERN void setproctitle(const char *fmt, ...);
 #endif
 

internal/error.h

@@ -43,6 +43,7 @@ extern long rb_backtrace_length_limit;
 extern VALUE rb_eEAGAIN;
 extern VALUE rb_eEWOULDBLOCK;
 extern VALUE rb_eEINPROGRESS;
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 3, 0)
 void rb_report_bug_valist(VALUE file, int line, const char *fmt, va_list args);
 NORETURN(void rb_async_bug_errno(const char *,int));
 const char *rb_builtin_type_name(int t);
@@ -114,6 +115,7 @@ void rb_deprecated_method_to_be_removed(const char *);
 # define RBIMPL_TODO0(x)
 #endif
 #define RBIMPL_TODO(message) RBIMPL_TODO0("TODO: " message)
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 6, 0)
 VALUE rb_syntax_error_append(VALUE, VALUE, int, int, rb_encoding*, const char*, va_list);
 PRINTF_ARGS(void rb_enc_warn(rb_encoding *enc, const char *fmt, ...), 2, 3);
 PRINTF_ARGS(void rb_sys_enc_warning(rb_encoding *enc, const char *fmt, ...), 2, 3);
@@ -124,6 +126,7 @@ VALUE rb_name_err_new(VALUE mesg, VALUE recv, VALUE method);
 VALUE rb_nomethod_err_new(VALUE mesg, VALUE recv, VALUE method, VALUE args, int priv);
 VALUE rb_key_err_new(VALUE mesg, VALUE recv, VALUE name);
 PRINTF_ARGS(VALUE rb_warning_string(const char *fmt, ...), 1, 2);
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 0)
 NORETURN(void rb_vraise(VALUE, const char *, va_list));
 NORETURN(static inline void rb_raise_cstr(VALUE etype, const char *mesg));
 NORETURN(static inline void rb_raise_cstr_i(VALUE etype, VALUE mesg));

vm_core.h

@@ -1661,6 +1661,7 @@ extern void rb_vmdebug_debug_print_post(const rb_execution_context_t *ec, const
 #define SDR2(cfp) rb_vmdebug_stack_dump_raw(GET_EC(), (cfp))
 void rb_vm_bugreport(const void *);
 typedef void (*ruby_sighandler_t)(int);
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 4, 5)
 NORETURN(void rb_bug_for_fatal_signal(ruby_sighandler_t default_sighandler, int sig, const void *, const char *fmt, ...));
 
 /* functions about thread/vm execution */

vm_debug.h

@@ -87,6 +87,7 @@ extern enum ruby_debug_log_mode {
     ruby_debug_log_file     = 0x04,
 } ruby_debug_log_mode;
 
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 4, 5)
 void ruby_debug_log(const char *file, int line, const char *func_name, const char *fmt, ...);
 void ruby_debug_log_print(unsigned int n);
 bool ruby_debug_log_filter(const char *func_name);