On Fri, Feb 14, 2020 at 12:24:30AM +0100, Jason Merrill wrote: > On 2/11/20 8:54 PM, Marek Polacek wrote: > > Since <https://gcc.gnu.org/ml/gcc-patches/2015-02/msg00556.html> we > > attempt to value-initialize in build_vec_init even when there's no > > initializer but the type has a constexpr default constructor. But > > build_value_init doesn't work in templates, so I think let's avoid > > this scenario; we'll go to the normal build_aggr_init path then. > > > > Bootstrapped/regtested on x86_64-linux, ok for trunk and branches? > > > > PR c++/93676 - value-init crash in template. > > * init.c (build_vec_init): Don't perform value-init in a template. > > Hmm, we really shouldn't even be calling build_vec_init in a template, that > builds up a lot of garbage that we'll throw away at the end of build_new.
Ah, it's true that build_new will just creates a NEW_EXPR in a template and doesn't use the result of build_new_1. Unfortunately I can't just call build_special_member_call like we do in build_new_1 since that crashes for array types. Maybe just return NULL_TREE then? I was afraid we would miss diagnostics but it seems to work. Bootstrapped/regtested on x86_64-linux, ok for trunk? -- >8 -- Since <https://gcc.gnu.org/ml/gcc-patches/2015-02/msg00556.html> we attempt to value-initialize in build_vec_init even when there's no initializer but the type has a constexpr default constructor. But build_value_init doesn't work in templates, and build_vec_init creates a lot of garbage that would not be used anyway, so don't call it in a template. PR c++/93676 - value-init crash in template. * init.c (build_new_1): Don't call build_vec_init in a template. * g++.dg/cpp0x/nsdmi-template19.C: New test. --- gcc/cp/init.c | 6 ++++++ gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C | 13 +++++++++++++ 2 files changed, 19 insertions(+) create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C diff --git a/gcc/cp/init.c b/gcc/cp/init.c index d480660445e..332a9b04679 100644 --- a/gcc/cp/init.c +++ b/gcc/cp/init.c @@ -3554,6 +3554,12 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts, error ("parenthesized initializer in array new"); return error_mark_node; } + /* We shouldn't call build_vec_init in a template: it could call + build_value_init which doesn't work in templates, and it would + create a lot of garbage that would not be used anyway, so return + a null tree and let build_new create a NEW_EXPR instead. */ + if (processing_template_decl) + return NULL_TREE; init_expr = build_vec_init (data_addr, cp_build_binary_op (input_location, diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C new file mode 100644 index 00000000000..f3e2cb87fd6 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C @@ -0,0 +1,13 @@ +// PR c++/93676 - value-init crash in template. +// { dg-do compile { target c++11 } } + +struct P { + int x = 0; +}; + +template<class T> +struct S { + S() { new P[2][2]; } +}; + +S<int> s; base-commit: 58f2e59ad36ca05444cb0a57ad1f13cc58e52755 -- Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
