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From: "aldot at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/102973] New: possible inconsistency in
 procptr_assignment handling when matching ASSOCIATE
Date: Wed, 27 Oct 2021 20:43:33 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102973

            Bug ID: 102973
           Summary: possible inconsistency in procptr_assignment handling
                    when matching ASSOCIATE
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: aldot at gcc dot gnu.org
  Target Milestone: ---

As noted in https://gcc.gnu.org/pipermail/fortran/2018-September/050809.html

i spotted one
(pre-existing) possible inconsistency that i did overlook back then:

gfc_match_associate () reads
...
      if (gfc_match (" %e", &newAssoc->target) !=3D MATCH_YES)
        {
          /* Have another go, allowing for procedure pointer selectors.  */
          gfc_matching_procptr_assignment =3D 1;
          if (gfc_match (" %e", &newAssoc->target) !=3D MATCH_YES)
            {
              gfc_error ("Invalid association target at %C");
              goto assocListError;
            }
          gfc_matching_procptr_assignment =3D 0;
        }

i.e. we retry a match, but in the second attempt we turn on procptr
assignment matching and if that works, we turn procptr assignment
matching off again.
But if we fail that retry, we forget to turn it off again.
I suppose we should:

$ svn diff -x -p gcc/fortran/match.c
Index: gcc/fortran/match.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
--- gcc/fortran/match.c (revision 264040)
+++ gcc/fortran/match.c (working copy)
@@ -1898,13 +1898,16 @@ gfc_match_associate (void)
       if (gfc_match (" %e", &newAssoc->target) !=3D MATCH_YES)
  {
    /* Have another go, allowing for procedure pointer selectors.  */
+   match m;
+
    gfc_matching_procptr_assignment =3D 1;
-   if (gfc_match (" %e", &newAssoc->target) !=3D MATCH_YES)
+   m =3D gfc_match (" %e", &newAssoc->target);
+   gfc_matching_procptr_assignment =3D 0;
+   if (m !=3D MATCH_YES)
      {
        gfc_error ("Invalid association target at %C");
        goto assocListError;
      }
-   gfc_matching_procptr_assignment =3D 0;
  }
       newAssoc->where =3D gfc_current_locus;


Untested. Maybe someone wants to give it a whirl...
If it wrecks havoc then leaving it set deliberately deserves at least a
comment.

PS: It would be nice to get rid of gfc_matching_procptr_assignment,
gfc_matching_ptr_assignment, gfc_matching_prefix, FWIW.=