[Bug c/84919] [8/9/10 Regression] error: passing argument 1 to restrict-qualified parameter aliases with argument 5 [-Werror=restrict]

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84919

--- Comment #17 from Martin Sebor <msebor at gcc dot gnu.org> ---
The patch below avoids the warning.  Unfortunately, as a result of bug 92666,
it triggers another bogus warning during bootstrap.

Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c     (revision 278975)
+++ gcc/c-family/c-common.c     (working copy)
@@ -5763,8 +5763,26 @@ check_function_arguments (location_t loc, const_tr
   if (warn_format)
     check_function_sentinel (fntype, nargs, argarray);

-  if (warn_restrict)
-    warned_p |= check_function_restrict (fndecl, fntype, nargs, argarray);
+  if (fndecl && fndecl_built_in_p (fndecl, BUILT_IN_NORMAL))
+    {
+      switch (DECL_FUNCTION_CODE (fndecl))
+       {
+       case BUILT_IN_SPRINTF:
+       case BUILT_IN_SPRINTF_CHK:
+       case BUILT_IN_SNPRINTF:
+       case BUILT_IN_SNPRINTF_CHK:
+         /* Let the sprintf pass handle these.  */
+         return warned_p;
+
+       default:
+         break;
+       }
+    }
+
+  /* check_function_restrict sets the DECL_READ_P for arguments
+     so it must be called unconiditionally.  */
+  warned_p |= check_function_restrict (fndecl, fntype, nargs, argarray);
+
   return warned_p;
 }