[Bug analyzer/109570] New: detect fclose on unopened or NULL files

[vanyacpp at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109570

            Bug ID: 109570
           Summary: detect fclose on unopened or NULL files
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: vanyacpp at gmail dot com
  Target Milestone: ---

While cleaning up one not particularly well written program I noticed this code
fragment:

FILE* file = fopen(...);
if (!file)
{
    fclose(file);
    return false;
}

Passing NULL to fclose is undefined behavior. Perhaps -fanalyzer could warn
about code like this?