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Subject: [Bug c++/99700] [10/11 Regression] uninitialized variable accepted
 as a constant expression in C++ 20
Date: Fri, 16 Apr 2021 13:25:14 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99700

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:baf05d54dc919c968d12de9d049e36e5bac10dec

commit r11-8216-gbaf05d54dc919c968d12de9d049e36e5bac10dec
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Apr 16 09:24:46 2021 -0400

    c++: partially initialized constexpr array [PR99700]

    Here, reduced_constant_expression_p is incorrectly returning true for a
    partially initialized array CONSTRUCTOR (in C++20 mode) because when the
    CONSTRUCTOR_NO_CLEARING flag is set, the predicate doesn't check that
    the CONSTRUCTOR spans the entire array like it does for class CONSTRUCT=
ORS.
    This patch adds a dedicated loop for the array case that simultaneously
    verifies the CONSTRUCTOR spans the entire array and is made up of valid
    constant expressions.

    gcc/cp/ChangeLog:

            PR c++/99700
            * constexpr.c (reduced_constant_expression_p): For array
            CONSTRUCTORs, use a dedicated loop that additionally verifies
            the CONSTRUCTOR spans the entire array.

    gcc/testsuite/ChangeLog:

            PR c++/99700
            * g++.dg/cpp2a/constexpr-init21.C: New test.=