From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2153) id 8C423386F808; Fri, 19 Mar 2021 23:29:06 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8C423386F808 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jakub Jelinek To: gcc-cvs@gcc.gnu.org Subject: [gcc r10-9468] c++: Fix zero initialization of flexible array members [PR99033] X-Act-Checkin: gcc X-Git-Author: Jakub Jelinek X-Git-Refname: refs/heads/releases/gcc-10 X-Git-Oldrev: a964f494cd5a90f631b8c0c01777a9899e0351ce X-Git-Newrev: ea535f59b19f65e5b313c990ee6c194a7b055bd7 Message-Id: <20210319232906.8C423386F808@sourceware.org> Date: Fri, 19 Mar 2021 23:29:06 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Mar 2021 23:29:06 -0000 https://gcc.gnu.org/g:ea535f59b19f65e5b313c990ee6c194a7b055bd7 commit r10-9468-gea535f59b19f65e5b313c990ee6c194a7b055bd7 Author: Jakub Jelinek Date: Thu Feb 11 17:24:17 2021 +0100 c++: Fix zero initialization of flexible array members [PR99033] array_type_nelts returns error_mark_node for type of flexible array members and build_zero_init_1 was placing an error_mark_node into the CONSTRUCTOR, on which e.g. varasm ICEs. I think there is nothing erroneous on zero initialization of flexible array members though, such arrays should simply get no elements, like they do if such classes are constructed (everything except when some larger initializer comes from an explicit initializer). So, this patch handles [] arrays in zero initialization like [0] arrays and fixes handling of the [0] arrays - the tree_int_cst_equal (max_index, integer_minus_one_node) check didn't do what it thought it would do, max_index is typically unsigned integer (sizetype) and so it is never equal to a -1. What the patch doesn't do and maybe would be desirable is if it returns error_mark_node for other reasons let the recursive callers not stick that into CONSTRUCTOR but return error_mark_node instead. But I don't have a testcase where that would be needed right now. 2021-02-11 Jakub Jelinek PR c++/99033 * init.c (build_zero_init_1): Handle zero initialiation of flexible array members like initialization of [0] arrays. Use integer_minus_onep instead of comparison to integer_minus_one_node and integer_zerop instead of comparison against size_zero_node. Formatting fixes. * g++.dg/ext/flexary38.C: New test. (cherry picked from commit 2dcdd15d0bafb9b45a8d7ff580217bd6ac1f0975) Diff: --- gcc/cp/init.c | 20 +++++++++++--------- gcc/testsuite/g++.dg/ext/flexary38.C | 18 ++++++++++++++++++ 2 files changed, 29 insertions(+), 9 deletions(-) diff --git a/gcc/cp/init.c b/gcc/cp/init.c index 8cdce278248..bbd33f46697 100644 --- a/gcc/cp/init.c +++ b/gcc/cp/init.c @@ -246,9 +246,12 @@ build_zero_init_1 (tree type, tree nelts, bool static_storage_p, /* Iterate over the array elements, building initializations. */ if (nelts) - max_index = fold_build2_loc (input_location, - MINUS_EXPR, TREE_TYPE (nelts), - nelts, integer_one_node); + max_index = fold_build2_loc (input_location, MINUS_EXPR, + TREE_TYPE (nelts), nelts, + build_one_cst (TREE_TYPE (nelts))); + /* Treat flexible array members like [0] arrays. */ + else if (TYPE_DOMAIN (type) == NULL_TREE) + max_index = build_minus_one_cst (sizetype); else max_index = array_type_nelts (type); @@ -260,20 +263,19 @@ build_zero_init_1 (tree type, tree nelts, bool static_storage_p, /* A zero-sized array, which is accepted as an extension, will have an upper bound of -1. */ - if (!tree_int_cst_equal (max_index, integer_minus_one_node)) + if (!integer_minus_onep (max_index)) { constructor_elt ce; /* If this is a one element array, we just use a regular init. */ - if (tree_int_cst_equal (size_zero_node, max_index)) + if (integer_zerop (max_index)) ce.index = size_zero_node; else ce.index = build2 (RANGE_EXPR, sizetype, size_zero_node, - max_index); + max_index); - ce.value = build_zero_init_1 (TREE_TYPE (type), - /*nelts=*/NULL_TREE, - static_storage_p, NULL_TREE); + ce.value = build_zero_init_1 (TREE_TYPE (type), /*nelts=*/NULL_TREE, + static_storage_p, NULL_TREE); if (ce.value) { vec_alloc (v, 1); diff --git a/gcc/testsuite/g++.dg/ext/flexary38.C b/gcc/testsuite/g++.dg/ext/flexary38.C new file mode 100644 index 00000000000..4fa987bcb41 --- /dev/null +++ b/gcc/testsuite/g++.dg/ext/flexary38.C @@ -0,0 +1,18 @@ +// PR c++/99033 +// { dg-do compile } +// { dg-options "" } + +struct T { int t; }; +struct S { char c; int T::*b[]; } a; +struct U { char c; int T::*b[0]; } b; +struct V { char c; int T::*b[1]; } c; +struct W { char c; int T::*b[2]; } d; + +void +foo () +{ + a.c = 1; + b.c = 2; + c.c = 3; + d.c = 4; +}