From 8f9dd1b0bdd935592ba151e9d843fddf6193afbc Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Wed, 19 Feb 2020 16:36:38 -0500 Subject: c++: Fix wrong-code with non-constexpr constructor [PR93169] In order to detect modifying constant objects in constexpr evaluation, which is UB, in r10-2655 I added code that sets TREE_READONLY on CONSTRUCTORs of const-qualified objects after they have been fully constructed. But I never made sure that what we're setting the flag on actually is a CONSTRUCTOR. Consequently, as this test case shows, we could set TREE_READONLY on a VAR_DECL that in fact wasn't constant, causing problems later. Fixed by setting the flag on CONSTRUCTORs only, and only when the evaluation produced something constant. 2020-02-19 Marek Polacek PR c++/93169 - wrong-code with a non-constexpr constructor. * constexpr.c (cxx_eval_call_expression): Only set TREE_READONLY on constant CONSTRUCTORs. * g++.dg/cpp0x/constexpr-93169.C: New test. --- gcc/cp/constexpr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'gcc/cp/constexpr.c') diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index bf7a264..128f760 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -2474,7 +2474,8 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t, /*lval*/false, non_constant_p, overflow_p); - TREE_READONLY (e) = true; + if (TREE_CODE (e) == CONSTRUCTOR && !*non_constant_p) + TREE_READONLY (e) = true; } /* Forget the saved values of the callee's SAVE_EXPRs and -- cgit v1.1