[gcc r13-1605] c-family: Fix option check in handle_pragma_diagnostic [PR106252]

[Lewis Hyatt <lhyatt@gcc.gnu.org>]

https://gcc.gnu.org/g:cb7b01db7a1979a45fd1dce87a8738e80568520e

commit r13-1605-gcb7b01db7a1979a45fd1dce87a8738e80568520e
Author: Lewis Hyatt <lhyatt@gmail.com>
Date:   Mon Jul 11 08:12:33 2022 -0400

    c-family: Fix option check in handle_pragma_diagnostic [PR106252]
    
    In r13-1544, handle_pragma_diagnostic was refactored to support processing
    early pragmas. During that process the part looking up option arguments was
    inadvertenly moved too early, prior to checking the option was valid, causing
    PR106252. Fixed by moving the check back where it goes.
    
    gcc/c-family/ChangeLog:
    
            PR preprocessor/106252
            * c-pragma.cc (handle_pragma_diagnostic_impl): Don't look up the
            option argument prior to verifying the option was found.

Diff:
---
 gcc/c-family/c-pragma.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/gcc/c-family/c-pragma.cc b/gcc/c-family/c-pragma.cc
index 62bce2ed0f5..789719e6e6a 100644
--- a/gcc/c-family/c-pragma.cc
+++ b/gcc/c-family/c-pragma.cc
@@ -1009,10 +1009,6 @@ handle_pragma_diagnostic_impl ()
   if (early && !c_option_is_from_cpp_diagnostics (option_index))
     return;
 
-  const char *arg = NULL;
-  if (cl_options[option_index].flags & CL_JOINED)
-    arg = data.option_str + 1 + cl_options[option_index].opt_len;
-
   if (option_index == OPT_SPECIAL_unknown)
     {
       if (want_diagnostics)
@@ -1052,6 +1048,10 @@ handle_pragma_diagnostic_impl ()
       return;
     }
 
+  const char *arg = NULL;
+  if (cl_options[option_index].flags & CL_JOINED)
+    arg = data.option_str + 1 + cl_options[option_index].opt_len;
+
   struct cl_option_handlers handlers;
   set_default_handlers (&handlers, NULL);
   /* FIXME: input_location isn't the best location here, but it is