https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102990
--- Comment #14 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:6ba2a7e7474135b717c344030b114ffd6ad8ed7a commit r11-9711-g6ba2a7e7474135b717c344030b114ffd6ad8ed7a Author: Marek Polacek <pola...@redhat.com> Date: Tue Mar 22 18:42:27 2022 -0400 c++: FIX_TRUNC_EXPR in tsubst [PR102990] This is a crash where a FIX_TRUNC_EXPR gets into tsubst_copy_and_build where it hits gcc_unreachable (). The history of tsubst_copy_and_build/FIX_TRUNC_EXPR is such that it was introduced in r181478, but it did the wrong thing, whereupon it was turned into gcc_unreachable () in r258821 (see this thread: <https://gcc.gnu.org/pipermail/gcc-patches/2018-March/495853.html>). In a template, we should never create a FIX_TRUNC_EXPR (that's what conv_unsafe_in_template_p is for). But in this test we are NOT in a template when we call digest_nsdmi_init which ends up calling convert_like, converting 1.0e+0 to int, so convert_to_integer_1 gives us a FIX_TRUNC_EXPR. But then when we get to parsing f's parameters, we are in a template when processing decltype(Helpers{}), and since r268321, when the compound literal isn't instantiation-dependent and the type isn't type-dependent, finish_compound_literal falls back to the normal processing, so it calls digest_init, which does fold_non_dependent_init and since the FIX_TRUNC_EXPR isn't dependent, we instantiate and therefore crash in tsubst_copy_and_build. The fateful call to fold_non_dependent_init comes from massage_init_elt, We shouldn't be calling f_n_d_i on the result of get_nsdmi. This we can avoid by eschewing calling f_n_d_i on CONSTRUCTORs; their elements have already been folded. PR c++/102990 gcc/cp/ChangeLog: * typeck2.c (massage_init_elt): Avoid folding CONSTRUCTORs. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/nsdmi-template22.C: New test. * g++.dg/cpp0x/nsdmi-template23.C: New test. (cherry picked from commit f0530882d99abc410bb080051aa04e5cea848f18)
