From 4cee81365ad32ef947f500e4cf4b3514d88236c9 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Mon, 25 May 2020 18:04:39 -0400 Subject: [PATCH] c++: generic lambda and -fsanitize=vla-bound [PR93822] Within the generic lambda the VLA capture proxy VAR_DECL has DECL_VALUE_EXPR which is a NOP_EXPR to the VLA type of the proxy. The problem here was that when instantiating we were tsubsting that type twice, once for the type of the DECL and once for the type of the NOP_EXPR, and getting two different (though equivalent) types. Then gimplify_type_sizes fixed up the type of the DECL, but that didn't affect the type of the NOP_EXPR, leading to sadness. Fixed by directly reusing the type from the DECL. gcc/cp/ChangeLog 2020-05-01 Jason Merrill PR c++/93822 * pt.c (tsubst_decl): Make sure DECL_VALUE_EXPR continues to have the same type as the variable. --- gcc/cp/ChangeLog | 6 ++++++ gcc/cp/pt.c | 9 +++++++++ 2 files changed, 15 insertions(+) diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 306ebf2c71f7..a4fac1932785 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,9 @@ +2020-05-25 Jason Merrill + + PR c++/93822 + * pt.c (tsubst_decl): Make sure DECL_VALUE_EXPR continues to have + the same type as the variable. + 2020-05-24 Iain Sandoe Backported from mainline diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index b8f03d185411..e025dd7a3887 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -14609,6 +14609,11 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain) if (DECL_HAS_VALUE_EXPR_P (t)) { tree ve = DECL_VALUE_EXPR (t); + /* If the DECL_VALUE_EXPR is converted to the declared type, + preserve the identity so that gimplify_type_sizes works. */ + bool nop = (TREE_CODE (ve) == NOP_EXPR); + if (nop) + ve = TREE_OPERAND (ve, 0); ve = tsubst_expr (ve, args, complain, in_decl, /*constant_expression_p=*/false); if (REFERENCE_REF_P (ve)) @@ -14616,6 +14621,10 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain) gcc_assert (TYPE_REF_P (type)); ve = TREE_OPERAND (ve, 0); } + if (nop) + ve = build_nop (type, ve); + else + gcc_checking_assert (TREE_TYPE (ve) == type); SET_DECL_VALUE_EXPR (r, ve); } if (CP_DECL_THREAD_LOCAL_P (r) -- 2.47.2