[Bug ada/58881] crash for instantiation on tagged private type with unknown discriminants

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58881

--- Comment #8 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:12f3c63de3b4e53b63347c4bee6a82ce66d0078a

commit r16-4934-g12f3c63de3b4e53b63347c4bee6a82ce66d0078a
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Sun Nov 2 19:36:16 2025 +0100

    Ada: Fix crash on tagged private type with unknown discriminants

    This is an old issue with the extension of a tagged private type declared
    with unknown discriminants in the public part of a generic child unit,
    although the generic context is not a key factor (i.e. this also happens
    for a nongeneric child unit).  The public part of a child unit does not
    have visibility on the private part of its parent, so the extension also
    has unknown discriminants.

    gcc/ada/
            PR ada/58881
            * sem_ch3.adb (Build_Derived_Private_Type): Build the underlying
            full view when the derivation occurs in the public part of the
            scope of the parent.
            (Build_Derived_Record_Type): Propagate Has_Unknown_Discriminants
            in the same circumstances.
            (Constrain_Discriminated_Type): Give a specific error message for
            any type with the Has_Unknown_Discriminants flag.

    gcc/testsuite/
            * gnat.dg/specs/unknown_discr1.ads: New test.
            * gnat.dg/specs/unknown_discr1_pkg.ads: New helper.
            * gnat.dg/specs/unknown_discr1_pkg-child.ads: Likewise.
            * gnat.dg/specs/unknown_discr1_pkg-g.ads: Likewise.
            * gnat.dg/specs/unknown_discr1_pkg-inst.ads: Likewise.