[gcc r17-2275] cobol: add diagnostic for SORT without defined key

https://gcc.gnu.org/g:e7140c283c74706e75d0e515cd824c7043705234

commit r17-2275-ge7140c283c74706e75d0e515cd824c7043705234
Author: James K. Lowden <[email protected]>
Date:   Wed Jul 8 18:16:27 2026 -0400

    cobol: add diagnostic for SORT without defined key
    
    gcc/cobol/ChangeLog:
    
            PR cobol/126106
            * parse.y: Report error instead of crashing.

Diff:
---
 gcc/cobol/parse.y | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gcc/cobol/parse.y b/gcc/cobol/parse.y
index 22445ed5b4c5..2d9263d983c5 100644
--- a/gcc/cobol/parse.y
+++ b/gcc/cobol/parse.y
@@ -9879,6 +9879,10 @@ sort_table:     SORT tableref[table] sort_keys sort_dup sort_seq {
 		    error_msg(@1, "%s has no OCCURS clause", $table->field->name);
                     YYERROR;
 		  }
+		  if( !$table->field->occurs.keys ) {
+		    error_msg(@1, "%s: no key defined", $table->field->name);
+                    YYERROR;
+		  }
                   cbl_key_t
                     key = cbl_key_t($table->field->occurs.keys[0]),
                     guess(1, &$table->field);