From 247d1b97a43054b489b91a17dc7418b85b19857c Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Wed, 17 Jun 2020 09:19:02 -0400 Subject: 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. --- gcc/cp/constexpr.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'gcc/cp/constexpr.c') diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index c01c42b..f766abd 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -7093,6 +7093,19 @@ fold_non_dependent_expr (tree t, return maybe_constant_value (t, object, manifestly_const_eval); } +/* Like fold_non_dependent_expr, but if EXPR couldn't be folded to a constant, + return the original expression. */ + +tree +maybe_fold_non_dependent_expr (tree expr, + tsubst_flags_t complain/*=tf_warning_or_error*/) +{ + tree t = fold_non_dependent_expr (expr, complain); + if (t && TREE_CONSTANT (t)) + return t; + + return expr; +} /* Like maybe_constant_init but first fully instantiate the argument. */ -- cgit v1.1