On Thu, Feb 20, 2020 at 12:13:07AM +0000, Jason Merrill wrote: > On 2/19/20 10:15 PM, Marek Polacek wrote: > > 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. > > We should call it for strip_array_types (type).
Since build_special_member_call takes an expression we'd have to modify its type which I think is not pretty, but it works. Is this along the lines you had in mind? I think I still like the v1 patch best but if you're fine with the following, then am I. -- >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, 18 insertions(+), 1 deletion(-) 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..c60f332313a 100644 --- a/gcc/cp/init.c +++ b/gcc/cp/init.c @@ -3511,13 +3511,17 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts, explicit_value_init_p = true; } - if (processing_template_decl && explicit_value_init_p) + if (processing_template_decl) { /* build_value_init doesn't work in templates, and we don't need the initializer anyway since we're going to throw it away and rebuild it at instantiation time, so just build up a single constructor call to get any appropriate diagnostics. */ init_expr = cp_build_fold_indirect_ref (data_addr); + /* Avoid an ICE when converting to a base in build_simple_base_path. + We'll throw this all away anyway, and build_new will create + a NEW_EXPR. */ + TREE_TYPE (init_expr) = strip_array_types (TREE_TYPE (init_expr)); if (type_build_ctor_call (elt_type)) init_expr = build_special_member_call (init_expr, complete_ctor_identifier, 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: 4be779f59b04947324889b7e1488fb9a68c81d53 -- Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
