[Bug modula2/114055] New: poor error message generated during when checking the BY constant expression type

[Bug modula2/114055] New: poor error message generated during when checking the BY constant expression type

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114055

            Bug ID: 114055
           Summary: poor error message generated during when checking the
                    BY constant expression type
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: modula2
          Assignee: gaius at gcc dot gnu.org
          Reporter: gaius at gcc dot gnu.org
  Target Milestone: ---

This is a minor follow on bug to 114026.

$ cat forloopby.mod
MODULE forloopby ;


PROCEDURE init ;
CONST
   increment = CARDINAL (1) ;
VAR
   i: INTEGER ;
BEGIN
   FOR i := 0 TO 10 BY increment DO
   END
END init ;


BEGIN
   init
END forloopby.

$ gm2 forloopby.mod 
forloopby.mod: In function ‘init’:
forloopby.mod:10:8: error: In procedure ‘init’: type incompatibility between
‘INTEGER’ and ‘CARDINAL’
   10 |    FOR i := 0 TO 10 BY increment DO
      |        ^

which could be improved to mention the BY constant expression and designator
expression type fail.

[Bug modula2/114055] poor error message generated during when checking the BY constant expression type

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114055

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2024-02-22
     Ever confirmed|0                           |1

--- Comment #1 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Confirmed.

[Bug modula2/114055] poor error message generated during when checking the BY constant expression type

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114055

--- Comment #2 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Created attachment 57497
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57497&action=edit
Proposed fix

The fix marks a constant created during the default BY clause of the FOR loop
as internal.  The type checker will always return true if checking against an
internal const.

$ cat forloopby.mod
MODULE forloopby ;


PROCEDURE init ;
CONST
   increment = CARDINAL (1) ;
VAR
   i: INTEGER ;
BEGIN
   FOR i := 0 TO 10 BY increment DO
   END
END init ;


BEGIN
   init
END forloopby.

 gm2 forloopby.mod 
forloopby.mod:10:8: error: In procedure ‘init’: type expression incompatibility
between ‘INTEGER’ and ‘CARDINAL’ detected between the designator ‘i’ and the BY
constant expression ‘increment’ in the FOR loop
   10 |    FOR i := 0 TO 10 BY increment DO
      |        ^~~~~~~~~~~~~~~~~~~~~~~~~

It also succeeds when compiling a for loop with a subrange which does not
include 1.

$ cat forloopby2.mod 
MODULE forloopby2 ;

TYPE
   negative = [-10..-1] ;


PROCEDURE init ;
VAR
   i: negative ;
BEGIN
   FOR i := MIN (negative) TO MAX (negative) DO
   END
END init ;


BEGIN
   init
END forloopby2.

$ gm2 forloopby2.mod

[Bug modula2/114055] poor error message generated during when checking the BY constant expression type

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114055

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Gaius Mulley <gaius@gcc.gnu.org>:

https://gcc.gnu.org/g:c1667b1ef538e4da10cf83bdf1ae62d7bdd96128

commit r14-9136-gc1667b1ef538e4da10cf83bdf1ae62d7bdd96128
Author: Gaius Mulley <gaiusmod2@gmail.com>
Date:   Thu Feb 22 15:02:19 2024 +0000

    PR modula2/114055 improve error message when checking the BY constant

    The fix marks a constant created during the default BY clause of the
    FOR loop as internal.  The type checker will always return true if
    checking against an internal const.

    gcc/m2/ChangeLog:

            PR modula2/114055
            * gm2-compiler/M2Check.mod (Import): IsConstLitInternal and
            IsConstLit.
            (isInternal): New procedure function.
            (doCheck): Test for isInternal in either operand and early
            return true.
            * gm2-compiler/M2Quads.mod (PushOne): Rewrite with extra
            parameter internal.
            (BuildPseudoBy): Add TRUE parameter to PushOne call.
            (BuildIncProcedure): Add FALSE parameter to PushOne call.
            (BuildDecProcedure): Add FALSE parameter to PushOne call.
            * gm2-compiler/M2Range.mod (ForLoopBeginTypeCompatible):
            Uncomment code and tidy up error string.
            * gm2-compiler/SymbolTable.def (PutConstLitInternal):
            New procedure.
            (IsConstLitInternal): New procedure function.
            * gm2-compiler/SymbolTable.mod (PutConstLitInternal):
            New procedure.
            (IsConstLitInternal): New procedure function.
            (SymConstLit): New field IsInternal.
            (CreateConstLit): Initialize IsInternal to FALSE.

    gcc/testsuite/ChangeLog:

            PR modula2/114055
            * gm2/pim/fail/forloopby.mod: New test.
            * gm2/pim/pass/forloopby2.mod: New test.

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

[Bug modula2/114055] poor error message generated during when checking the BY constant expression type

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114055

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

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

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