[Bug fortran/95106] New: Bogus warning from module with long name and an equivalence

[Bug fortran/95106] New: Bogus warning from module with long name and an equivalence

[gscfq@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

            Bug ID: 95106
           Summary: Bogus warning from module with long name and an
                    equivalence
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gscfq@t-online.de
  Target Milestone: ---

Name length 59 ok, suspicious warning for 60..63 :


$ cat z1_59.f90
module m2345678901234567890123456789012345678901234567890123456789
   real :: a(4), u(3,2)
   real :: b(4), v(4,2)
   equivalence (a(1),u(1,1)), (b(1),v(1,1))
end


$ cat z1_60.f90
module m23456789012345678901234567890123456789012345678901234567890
   real :: a(4), u(3,2)
   real :: b(4), v(4,2)
   equivalence (a(1),u(1,1)), (b(1),v(1,1))
end


$ cat z1_63.f90
module m23456789012345678901234567890123456789012345678901234567890123
   real :: a(4), u(3,2)
   real :: b(4), v(4,2)
   equivalence (a(1),u(1,1)), (b(1),v(1,1))
end


$ gfortran-11-20200510 -c z1_59.f90
$
$ gfortran-11-20200510 -c z1_60.f90
z1_60.f90:1:67:

    1 | module m23456789012345678901234567890123456789012345678901234567890
      |                                                                   1
Warning: Named COMMON block
'm23456789012345678901234567890123456789012345678901234567890.eq.1' at (1)
shall be of the same size as elsewhere (24 vs 32 bytes)

[Bug fortran/95106] Bogus warning from module with long name and an equivalence

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |anlauf at gcc dot gnu.org
   Last reconfirmed|                            |2020-05-21
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
           Keywords|                            |wrong-code
           Priority|P3                          |P4

--- Comment #1 from anlauf at gcc dot gnu.org ---
The warning is not only bogus, but indicates that something goes wrong.

Doing an "nm" on the resulting object files, it seems one equivalence is
missing for names of length 60+.

For z1_59.o:

0000000000000020 C
m2345678901234567890123456789012345678901234567890123456789.eq.0_
0000000000000018 C
m2345678901234567890123456789012345678901234567890123456789.eq.1_

For z1_60.o:

0000000000000020 C
m23456789012345678901234567890123456789012345678901234567890.eq._

It seems it cannot disambiguate the two equivalences any more,
and treat them as a single common.

[Bug fortran/95106] Bogus warning from module with long name and an equivalence

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

--- Comment #2 from anlauf at gcc dot gnu.org ---
Something like

diff --git a/gcc/fortran/trans-common.c b/gcc/fortran/trans-common.c
index bf163bc4f52..06313873002 100644
--- a/gcc/fortran/trans-common.c
+++ b/gcc/fortran/trans-common.c
@@ -242,8 +242,8 @@ static tree
 gfc_sym_mangled_common_id (gfc_common_head *com)
 {
   int has_underscore;
-  char mangled_name[GFC_MAX_MANGLED_SYMBOL_LEN + 1];
-  char name[GFC_MAX_SYMBOL_LEN + 1];
+  char mangled_name[GFC_MAX_MANGLED_SYMBOL_LEN + 10];
+  char name[GFC_MAX_SYMBOL_LEN + 10];

   /* Get the name out of the common block pointer.  */
   strcpy (name, com->name);

prevents the truncation of the mangled name, including the .eq.0123_ part.

[Bug fortran/95106] Bogus warning from module with long name and an equivalence

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |anlauf at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #3 from anlauf at gcc dot gnu.org ---
Patch submitted for review:

https://gcc.gnu.org/pipermail/fortran/2020-May/054373.html

[Bug fortran/95106] Bogus warning from module with long name and an equivalence

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Harald Anlauf <anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:d176184d98a00ab379ae5959aed1908a79995e6b

commit r11-594-gd176184d98a00ab379ae5959aed1908a79995e6b
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sun May 24 21:35:04 2020 +0200

    PR fortran/95106 - truncation of long symbol names with EQUIVALENCE

            For long module names, the generated name-mangled symbol was
            truncated, leading to bogus warnings about COMMON block
            mismatches.  Provide sufficiently large temporaries.

    gcc/fortran/

    2020-05-24  Harald Anlauf  <anlauf@gmx.de>

            PR fortran/95106
            * trans-common.c (gfc_sym_mangled_common_id): Enlarge temporaries
            for name-mangling.

    gcc/testsuite/

    2020-05-24  Harald Anlauf  <anlauf@gmx.de>

            PR fortran/95106
            * gfortran.dg/equiv_11.f90: New test.

[Bug fortran/95106] Bogus warning from module with long name and an equivalence

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #5 from anlauf at gcc dot gnu.org ---
Should be fixed, closing.

The test case assumes name mangling for equivalences as on Linux/x86.
If some platform has different conventions, I can add an appropriate
restriction.

Thanks for the report!

[Bug fortran/95106] Bogus warning from module with long name and an equivalence

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Harald Anlauf
<anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:1e20cd1b583347cb2ea8591a45d99df143f7c41a

commit r10-8255-g1e20cd1b583347cb2ea8591a45d99df143f7c41a
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sun May 24 21:35:04 2020 +0200

    PR fortran/95106 - truncation of long symbol names with EQUIVALENCE

            For long module names, the generated name-mangled symbol was
            truncated, leading to bogus warnings about COMMON block
            mismatches.  Provide sufficiently large temporaries.

    gcc/fortran/

    2020-05-24  Harald Anlauf  <anlauf@gmx.de>

            PR fortran/95106
            * trans-common.c (gfc_sym_mangled_common_id): Enlarge temporaries
            for name-mangling.

    gcc/testsuite/

    2020-05-24  Harald Anlauf  <anlauf@gmx.de>

            PR fortran/95106
            * gfortran.dg/equiv_11.f90: New test.

[Bug fortran/95106] Bogus warning from module with long name and an equivalence

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95106

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Harald Anlauf
<anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:371739d01d00ae4c55902e0937b73ddee7d66391

commit r9-8655-g371739d01d00ae4c55902e0937b73ddee7d66391
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sun May 24 21:35:04 2020 +0200

    PR fortran/95106 - truncation of long symbol names with EQUIVALENCE

            For long module names, the generated name-mangled symbol was
            truncated, leading to bogus warnings about COMMON block
            mismatches.  Provide sufficiently large temporaries.

    gcc/fortran/

    2020-05-24  Harald Anlauf  <anlauf@gmx.de>

            PR fortran/95106
            * trans-common.c (gfc_sym_mangled_common_id): Enlarge temporaries
            for name-mangling.

    gcc/testsuite/

    2020-05-24  Harald Anlauf  <anlauf@gmx.de>

            PR fortran/95106
            * gfortran.dg/equiv_11.f90: New test.

    (cherry picked from commit d176184d98a00ab379ae5959aed1908a79995e6b)