[Bug modula2/110246] New: Using variables of type CHAR or BYTE as array index does not work

[Bug modula2/110246] New: Using variables of type CHAR or BYTE as array index does not work

[admin@tho-otto.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110246

            Bug ID: 110246
           Summary: Using variables of type CHAR or BYTE as array index
                    does not work
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: modula2
          Assignee: gaius at gcc dot gnu.org
          Reporter: admin@tho-otto.de
  Target Milestone: ---

In the following example:

IMPLEMENTATION MODULE foo;

FROM SYSTEM IMPORT BYTE;

VAR arr: ARRAY['A'..'Z'] OF INTEGER;
VAR ch: CHAR;

BEGIN
  FOR ch := 'A' TO 'Z' DO arr[ch] := 0 END;
END foo.

I get error messages:

/usr/lib64/gcc/x86_64-suse-linux/13/m2/m2pim/COROUTINES.def:37:1: error: type
incompatibility, attempting to use a string ('_T38') when a CHAR is expected
/usr/lib64/gcc/x86_64-suse-linux/13/m2/m2pim/COROUTINES.def:37:1: error: type
incompatibility, attempting to use a string ('_T38') when a CHAR is expected
/usr/lib64/gcc/x86_64-suse-linux/13/m2/m2pim/COROUTINES.def:37:1: error: type
incompatibility, attempting to use a string ('_T38') when a CHAR is expected
/usr/lib64/gcc/x86_64-suse-linux/13/m2/m2pim/COROUTINES.def:37:1: error: type
incompatibility, attempting to use a string ('_T38') when a CHAR is expected

(note also the totally unrelated source line in the error message)

Changing the type of ch to BYTE i get instead:

/usr/lib64/gcc/x86_64-suse-linux/13/m2/m2pim/COROUTINES.def:37:1: error: left
operand ‘ch’ of type ‘BYTE’ is not allowed in binary expression +

[Bug modula2/110246] Using variables of type CHAR or BYTE as array index does not work

[admin@tho-otto.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110246

--- Comment #1 from Thorsten Otto <admin@tho-otto.de> ---
Edit: the problem seems to be caused by using a FOR loop. Changing it to a
similar WHILE loop:

  ch := 'A';
  WHILE ch <= 'Z' DO arr[ch] := 0; INC(ch); END;

does work without problems.

[Bug modula2/110246] Using variables of type CHAR or BYTE as array index does not work

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110246

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Gaius Mulley
<gaius@gcc.gnu.org>:

https://gcc.gnu.org/g:3e9aaa9bcb2fc64e64f4e8a2aa0f6f7395a21c52

commit r13-7622-g3e9aaa9bcb2fc64e64f4e8a2aa0f6f7395a21c52
Author: Gaius Mulley <gaiusmod2@gmail.com>
Date:   Fri Jul 28 15:00:29 2023 +0100

    PR modula2/109729 cannot use a CHAR type as a FOR loop iterator

    This patch introduces a new quadruple ArithAddOp which is used in
    the construction of FOR loop to ensure that when constant folding
    is applied it does not concatenate two constant char operands into
    a string constant.  Overloading only occurs with constant operands.

    gcc/m2/ChangeLog:

            PR modula2/109729
            PR modula2/110246
            * gm2-compiler/M2GenGCC.mod (CodeStatement): Detect
            ArithAddOp and call CodeAddChecked.
            (ResolveConstantExpressions): Detect ArithAddOp and call
            FoldArithAdd.
            (FoldArithAdd): New procedure.
            (FoldAdd): Refactor to use FoldArithAdd.
            * gm2-compiler/M2Quads.def (QuadOperator): Add ArithAddOp.
            * gm2-compiler/M2Quads.mod: Remove commented imports.
            (QuadFrame): Changed comments to use GNU coding standards.
            (ArithPlusTok): New global variable.
            (BuildForToByDo): Use ArithPlusTok instead of PlusTok.
            (MakeOp): Detect ArithPlusTok and return ArithAddOp.
            (WriteQuad): Add ArithAddOp clause.
            (WriteOperator): Add ArithAddOp clause.
            (Init): Initialize ArithPlusTok.

    gcc/testsuite/ChangeLog:

            PR modula2/109729
            * gm2/pim/run/pass/ForChar.mod: New test.

    (cherry picked from commit ac7c9954ece9a75c5e7c3b76a4800f2432002487)

    Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>

[Bug modula2/110246] Using variables of type CHAR or BYTE as array index does not work

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110246

Gaius Mulley <gaius at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2023-07-28

--- Comment #3 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Confirmed thanks for the bug report.

[Bug modula2/110246] Using variables of type CHAR or BYTE as array index does not work

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110246

Gaius Mulley <gaius at gcc dot gnu.org> changed:

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

--- Comment #4 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Closing now that the patch has been applied.