[Bug ada/107536] New: [12 regression] Wrong 'not referenced' warning on renamed variable

[Bug ada/107536] New: [12 regression] Wrong 'not referenced' warning on renamed variable

[simon at pushface dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107536

            Bug ID: 107536
           Summary: [12 regression] Wrong 'not referenced' warning on
                    renamed variable
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: simon at pushface dot org
  Target Milestone: ---

Created attachment 53834
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53834&action=edit
Demonstrator

If a record has aspect Volatile_Full_Access, a renaming of one of the record’s
components will be reported as unreferenced even though it plainly is.

$ gnatmake -gnatwa -c -u -f renaming.adb -gnatl
gcc -c -gnatwa -gnatl renaming.adb

GNAT 12.2.0
Copyright 1992-2022, Free Software Foundation, Inc.


Compiling: renaming.adb
Source file time stamp: 2022-11-05 16:48:11
Compiled at: 2022-11-05 16:50:40

     1. procedure Renaming is
     2.
     3.    type T is record
     4.       Item : Integer;
     5.    end record;
     6.    A_T : T;
     7.    Item : Integer renames A_T.Item;
     8.
     9.    type VFA_T is record
    10.       Item : Integer;
    11.    end record
    12.    with Volatile_Full_Access;
    13.    A_VFA_T : VFA_T;
    14.    VFA_Item : Integer renames A_VFA_T.Item;
           |
        >>> warning: renamed variable "VFA_Item" is not referenced [-gnatwu]

    15.
    16. begin
    17.    Item := 42;
    18.    VFA_Item := 42;
    19. end Renaming;

 19 lines: No errors, 1 warning

This is also present on 12.1.0.

[Bug ada/107536] [12/13 regression] Wrong 'not referenced' warning on renamed variable

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107536

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.3
            Summary|[12 regression] Wrong 'not  |[12/13 regression] Wrong
                   |referenced' warning on      |'not referenced' warning on
                   |renamed variable            |renamed variable
           Keywords|                            |diagnostic
           Priority|P3                          |P4

[Bug ada/107536] [12/13 regression] Wrong 'not referenced' warning on renamed variable

[simon at pushface dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107536

--- Comment #1 from simon at pushface dot org ---
Also present in GCC 13-20221030.

[Bug ada/107536] [12/13/14 regression] Wrong 'not referenced' warning on renamed variable

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107536

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|12.3                        |12.4

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 12.3 is being released, retargeting bugs to GCC 12.4.

[Bug ada/107536] [12/13/14 regression] Wrong 'not referenced' warning on renamed variable

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107536

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ebotcazou at gcc dot gnu.org
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-05-11
     Ever confirmed|0                           |1

--- Comment #3 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
The variable is macro-substituted and indeed fools the warning.