COBOL: Prevent crash on invalid refmod literal (PR126104)

Fixes a crash in the COBOL compiler when encountering invalid `refmod` literals.

By James K. Lowden July 6, 2026 committed

This commit addresses a crash in the COBOL compiler that occurred when processing invalid refmod literals. A specific check in literal_refmod_valid within parse.y has been modified to prevent dereferencing a NULL pointer, resolving the issue reported in PR126104.

In Details

In gcc/cobol/parse.y, the literal_refmod_valid function previously failed to check for a NULL pointer before attempting to dereference it when validating refmod literals, causing a crash. This commit adds the necessary NULL check, fixing the bug reported in PR126104.

For Context

refmod: Likely refers to a 'referential modifier' or a similar construct within COBOL syntax, used for qualifying certain types of literals or references. The exact meaning depends on the specific COBOL dialect and context.
literal: A fixed value represented directly in source code, such as a number (e.g., 123), a string (e.g., 'hello'), or a boolean (TRUE).
parse.y: A file typically containing grammar rules for a parser generator like Bison (or Yacc), used here for the COBOL front-end to define the language's syntax.
NULL pointer: A pointer that does not point to any valid memory location. In C/C++, it's often represented by NULL or 0.

Filed Under: cobolcompilerparserbugfix

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