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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/53220] [4.7/4.8 Regression] g++ mis-compiles compound
 literals
Date: Tue, 28 Nov 2023 21:29:26 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D53220

--- Comment #23 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:305a2686c99bf9b57490419f25c79f6fb3ae0feb

commit r14-5941-g305a2686c99bf9b57490419f25c79f6fb3ae0feb
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Nov 28 13:54:47 2023 -0500

    c++: prvalue array decay [PR94264]

    My change for PR53220 made array to pointer decay for prvalue arrays
    ill-formed to catch well-defined C code that produces a dangling pointe=
r in
    C++ due to the shorter lifetime of compound literals.  This wasn't real=
ly
    correct, but wasn't a problem until C++17 added prvalue arrays, at which
    point it started rejecting valid C++ code.

    I wanted to make sure that we still diagnose the problematic code;
    -Wdangling-pointer covers the array-lit.c case, but I needed to extend
    -Wreturn-local-addr to handle the return case.

            PR c++/94264
            PR c++/53220

    gcc/c/ChangeLog:

            * c-typeck.cc (array_to_pointer_conversion): Adjust -Wc++-compat
            diagnostic.

    gcc/cp/ChangeLog:

            * call.cc (convert_like_internal): Remove obsolete comment.
            * typeck.cc (decay_conversion): Allow array prvalue.
            (maybe_warn_about_returning_address_of_local): Check
            for returning pointer to temporary.

    gcc/testsuite/ChangeLog:

            * c-c++-common/array-lit.c: Adjust.
            * g++.dg/cpp1z/array-prvalue1.C: New test.
            * g++.dg/ext/complit17.C: New test.=