From 25056bdf94d5f3e66bef039702f7fae799ef16b9 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Wed, 18 Nov 2020 22:49:59 -0500 Subject: [PATCH] c++: Fix crash with broken deduction from {} [PR97895] Unfortunately, the otherwise beautiful for (constructor_elt &elt : *CONSTRUCTOR_ELTS (init)) is not immune to an empty constructor, so we have to check CONSTRUCTOR_ELTS first. gcc/cp/ChangeLog: PR c++/97895 * pt.c (do_auto_deduction): Don't crash when the constructor has zero elements. gcc/testsuite/ChangeLog: PR c++/97895 * g++.dg/cpp0x/auto54.C: New test. --- gcc/cp/pt.c | 11 +++++++---- gcc/testsuite/g++.dg/cpp0x/auto54.C | 10 ++++++++++ 2 files changed, 17 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/auto54.C diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 1babf833d32..a1b6631d691 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -29250,10 +29250,13 @@ do_auto_deduction (tree type, tree init, tree auto_node, return error_mark_node; if (BRACE_ENCLOSED_INITIALIZER_P (init)) - /* We don't recurse here because we can't deduce from a nested - initializer_list. */ - for (constructor_elt &elt : *CONSTRUCTOR_ELTS (init)) - elt.value = resolve_nondeduced_context (elt.value, complain); + { + /* We don't recurse here because we can't deduce from a nested + initializer_list. */ + if (CONSTRUCTOR_ELTS (init)) + for (constructor_elt &elt : *CONSTRUCTOR_ELTS (init)) + elt.value = resolve_nondeduced_context (elt.value, complain); + } else init = resolve_nondeduced_context (init, complain); diff --git a/gcc/testsuite/g++.dg/cpp0x/auto54.C b/gcc/testsuite/g++.dg/cpp0x/auto54.C new file mode 100644 index 00000000000..0c1815a99bc --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/auto54.C @@ -0,0 +1,10 @@ +// PR c++/97895 +// { dg-do compile { target c++11 } } + +namespace std { + template struct initializer_list { + const T *ptr; + decltype(sizeof 0) n; + }; + auto a = {}; // { dg-error "unable to deduce" } +} -- 2.30.2