[Bug ada/115349] wrong Accum_Type inferred for a reduction expression

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115349

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Eric Botcazou <ebotcazou@gcc.gnu.org>:

https://gcc.gnu.org/g:09da4112cbb38de230973ea8296816371ecb38b4

commit r16-5950-g09da4112cbb38de230973ea8296816371ecb38b4
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Sun Dec 7 23:40:25 2025 +0100

    Ada: Fix wrong Accum_Type inferred for a reduction expression

    This was reported as a regression in GCC 14: the compiler resolves
    Accum_Type to Positive for a reduction expression whose "expected
    subtype" is Positive, which means that 0 cannot be used as initial
    value in the expression:

      Sum : Positive := V'Reduce ("+", 0);

    without always raising Constraint_Error as run time.  That's not the
    intent according to T. Taft in
      https://forum.ada-lang.io/t/regression-in-gnat-14/890
    so this changes the resolution to use the base type (Integer) instead.

    gcc/ada/
            PR ada/115349
            * sem_attr.adb (Resolve_Attribute) <Attribute_Reduce>: Use the base
            type as Accum_Type if the reducer is an operator from Standard and
            the type is numeric.  Use the type of the first operand for other
            operators.  Streamline the error message given for limited types.

    gcc/testsuite/
            * gnat.dg/reduce3.adb: New test.