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From: Marek Polacek <mpolacek@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-8216] c++: wrong error with constexpr COMPOUND_EXPR [PR105321] Date: Thu, 21 Apr 2022 14:18:47 +0000 (GMT) [thread overview] Message-ID: <20220421141847.97E5A3857C6F@sourceware.org> (raw) https://gcc.gnu.org/g:93b65ed9706e2ceb4be7b28c9ff9be759e68a614 commit r12-8216-g93b65ed9706e2ceb4be7b28c9ff9be759e68a614 Author: Marek Polacek <polacek@redhat.com> Date: Wed Apr 20 16:02:52 2022 -0400 c++: wrong error with constexpr COMPOUND_EXPR [PR105321] Here we issue a bogus error for the first assert in the test. Therein we have <retval> = (void) (VIEW_CONVERT_EXPR<bool>(yes) || handle_error ());, VIEW_CONVERT_EXPR<int>(value); which has a COMPOUND_EXPR, so we get to cxx_eval_constant_expression <case COMPOUND_EXPR>. The problem here is that we call 7044 /* Check that the LHS is constant and then discard it. */ 7045 cxx_eval_constant_expression (ctx, op0, 7046 true, non_constant_p, overflow_p, 7047 jump_target); where lval is always true, so the PARM_DECL 'yes' is not evaluated into its value. Fixed by always passing false for 'lval' in cxx_eval_logical_expression; there's no case where we actually expect an lvalue from a TRUTH_*. PR c++/105321 gcc/cp/ChangeLog: * constexpr.cc (cxx_eval_logical_expression): Always pass false for lval to cxx_eval_constant_expression. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/constexpr-105321.C: New test. Diff: --- gcc/cp/constexpr.cc | 9 ++++----- gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C | 18 ++++++++++++++++++ 2 files changed, 22 insertions(+), 5 deletions(-) diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index e89440e770f..fa65290e938 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -4566,19 +4566,18 @@ cxx_eval_bit_cast (const constexpr_ctx *ctx, tree t, bool *non_constant_p, static tree cxx_eval_logical_expression (const constexpr_ctx *ctx, tree t, tree bailout_value, tree continue_value, - bool lval, - bool *non_constant_p, bool *overflow_p) + bool, bool *non_constant_p, bool *overflow_p) { tree r; tree lhs = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0), - lval, - non_constant_p, overflow_p); + /*lval*/false, non_constant_p, + overflow_p); VERIFY_CONSTANT (lhs); if (tree_int_cst_equal (lhs, bailout_value)) return lhs; gcc_assert (tree_int_cst_equal (lhs, continue_value)); r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1), - lval, non_constant_p, + /*lval*/false, non_constant_p, overflow_p); VERIFY_CONSTANT (r); return r; diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C new file mode 100644 index 00000000000..adb6830ff22 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C @@ -0,0 +1,18 @@ +// PR c++/105321 +// { dg-do compile { target c++11 } } + +bool handle_error(); + +constexpr int echo(int value, bool yes = true) noexcept +{ + return (yes || handle_error()), value; +} + +static_assert(echo(10) == 10, ""); + +constexpr int echo2(int value, bool no = false) noexcept +{ + return (!no || handle_error()), value; +} + +static_assert(echo2(10) == 10, "");
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