https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:ae2ebf011fec926e003645c33c07a03619ea216a commit r11-1449-gae2ebf011fec926e003645c33c07a03619ea216a Author: Marek Polacek <pola...@redhat.com> Date: Wed Jun 17 09:19:02 2020 -0400 c++: ICE with IMPLICIT_CONV_EXPR in array subscript [PR95508] Since r10-7096 convert_like, when called in a template, creates an IMPLICIT_CONV_EXPR when we're converting to/from array type. In this test, we have e[f], and we're converting f (of type class A) to int, so convert_like in build_new_op_1 created the IMPLICIT_CONV_EXPR that got into cp_build_array_ref which calls maybe_constant_value. My patch above failed to adjust this spot to call fold_non_dependent_expr instead, which can handle codes like I_C_E in a template. Fixed by using a new function maybe_fold_non_dependent_expr, which, if the expr can't be evaluated to a constant, returns the original expression. gcc/cp/ChangeLog: PR c++/95508 * constexpr.c (maybe_fold_non_dependent_expr): New. * cp-tree.h (maybe_fold_non_dependent_expr): Declare. * typeck.c (cp_build_array_ref): Call maybe_fold_non_dependent_expr instead of maybe_constant_value. gcc/testsuite/ChangeLog: PR c++/95508 * g++.dg/template/conv16.C: New test.
