[Bug c/80528] New: reimplement gnulib's "useless-if-before-free" script as a compiler warning

[egall at gwmail dot gwu.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80528

            Bug ID: 80528
           Summary: reimplement gnulib's "useless-if-before-free" script
                    as a compiler warning
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: egall at gwmail dot gwu.edu
  Target Milestone: ---

Split off from Bug 80519

Gnulib has a script called "useless-if-before-free" that detects code like:
if (p) free(p);
and warns about it, since the "if" test is usually unneeded nowadays. It'd be
nice if GCC did this warning instead, so users wouldn't have to import a
separate script from gnulib just to check for this sort of thing.

Source for script:
https://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob;f=build-aux/useless-if-before-free;h=4e3f3a2658b105e8949f14ef85d733192c29be2c;hb=HEAD