[Bug c++/84463] [6/7 Regression] Supposedly-incompliant "error: '* key0' is not a constant expression"

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84463

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Fri Jun 22 21:12:32 2018
New Revision: 261956

URL: https://gcc.gnu.org/viewcvs?rev=261956&root=gcc&view=rev
Log:
        Backported from mainline
        2018-04-18  Jakub Jelinek  <jakub@redhat.com>

        PR c++/84463
        * typeck.c (cp_build_addr_expr_1): Move handling of offsetof-like
        tricks from here to ...
        * cp-gimplify.c (cp_fold) <case ADDR_EXPR>: ... here.  Only use it
        if INDIRECT_REF's operand is INTEGER_CST cast to pointer type.

        * g++.dg/cpp0x/constexpr-nullptr-1.C: Add -O1 to dg-options.
        * g++.dg/cpp0x/constexpr-nullptr-2.C: Expect different diagnostics
        in two cases.  Uncomment two other tests and add expected dg-error for
        them.
        * g++.dg/init/struct2.C: Cast to int rather than long to avoid
        -Wnarrowing diagnostics on some targets for c++11.
        * g++.dg/parse/array-size2.C: Remove xfail.
        * g++.dg/cpp0x/constexpr-84463.C: New test.

Added:
    branches/gcc-7-branch/gcc/testsuite/g++.dg/cpp0x/constexpr-84463.C
Modified:
    branches/gcc-7-branch/gcc/cp/ChangeLog
    branches/gcc-7-branch/gcc/cp/cp-gimplify.c
    branches/gcc-7-branch/gcc/cp/typeck.c
    branches/gcc-7-branch/gcc/testsuite/ChangeLog
    branches/gcc-7-branch/gcc/testsuite/g++.dg/cpp0x/constexpr-nullptr-1.C
    branches/gcc-7-branch/gcc/testsuite/g++.dg/cpp0x/constexpr-nullptr-2.C
    branches/gcc-7-branch/gcc/testsuite/g++.dg/init/struct2.C
    branches/gcc-7-branch/gcc/testsuite/g++.dg/parse/array-size2.C