[Bug c++/119303] [12/13/14/15 Regression] ICE: error reporting routines re-entered. in warning_at (diagnostic-global-context.cc:185)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119303

--- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:c7eec82942496520d6b0604aa945a89f279e2562

commit r15-9068-gc7eec82942496520d6b0604aa945a89f279e2562
Author: Marek Polacek <polacek@redhat.com>
Date:   Thu Mar 27 15:03:18 2025 -0400

    c++: fix reporting routines re-entered [PR119303]

    We crash while we call warning_at ("inline function used but never
defined")
    since it invokes dump_template_bindings -> tsubst -> ... -> convert_like ->
    ... -> c_common_truthvalue_conversion -> warning_at ("enum constant in
boolean
                                                         context")

    cp_truthvalue_conversion correctly gets complain=0 but it calls
    c_common_truthvalue_conversion from c-family which doesn't have
    a similar parameter.

    We can fix this by tweaking diagnostic_context::report_diagnostic to
    check for recursion after checking if the diagnostic was enabled.

            PR c++/116960
            PR c++/119303

    gcc/ChangeLog:

            * diagnostic.cc (diagnostic_context::report_diagnostic): Check for
            non-zero m_lock later, after checking diagnostic_enabled.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/lambda-uneval26.C: New test.
            * g++.dg/warn/undefined2.C: New test.

    Reviewed-by: Jason Merrill <jason@redhat.com>