[committed] fortran/openmp.cc: Fix var init and locus use to avoid uninit values [PR fortran/116661]

[Tobias Burnus]

This patch fixes an issue with unintialized variables causing random ICE.
Committed as r15-3581-g4e9265a474def9

* * *

However, follow-up work is needed as there are multiple issues:

* The check whether something is a identifier (integer parameter) and 
not just a constant expression did fail in some corner cases. → causes 
now reliably a testsuite FAIL.

* Some checks are also not quite right

* After gfc_match_expr, a gobble whitespace is missing

* I missed that 'fr(…)' and 'attr(…)' accept a list of values*

* The latter requires a different internal representation.

I have a partial fix for this, but the last two items remove some more 
work, hence, I defer this to the next patch.

Tobias

(*) It looks also as if there will be post-TR13 spec changes, but it is 
not clear whether those just change the wording or more.
commit 4e9265a474def98cb6cdb59c15fbcb7630ba330e
Author: Tobias Burnus <tbur...@baylibre.com>
Date:   Wed Sep 11 09:25:47 2024 +0200

    fortran/openmp.cc: Fix var init and locus use to avoid uninit values [PR fortran/116661]
    
    gcc/fortran/ChangeLog:
    
            PR fortran/116661
            * openmp.cc (gfc_match_omp_prefer_type): NULL init a gfc_expr
            variable and use right locus in gfc_error.

diff --git a/gcc/fortran/openmp.cc b/gcc/fortran/openmp.cc
index c04d8b0f528..1145e2ff890 100644
--- a/gcc/fortran/openmp.cc
+++ b/gcc/fortran/openmp.cc
@@ -1860,6 +1860,7 @@ gfc_match_omp_prefer_type (char **pref_str, int *pref_str_len, int **pref_int_ar
 		  }
 		fr_found = true;
 		gfc_symbol *sym = NULL;
+		e = NULL;
 		locus loc = gfc_current_locus;
 		if (gfc_match_symbol (&sym, 0) != MATCH_YES
 		    || gfc_match (" _") == MATCH_YES)
@@ -1881,7 +1882,7 @@ gfc_match_omp_prefer_type (char **pref_str, int *pref_str_len, int **pref_int_ar
 		  {
 		    gfc_error ("Expected constant integer identifier or "
 			       "non-empty default-kind character literal at %L",
-			       &e->where);
+			       &loc);
 		    gfc_free_expr (e);
 		    return MATCH_ERROR;
 		  }