On Tue, Feb 25, 2020 at 01:55:24PM -0500, Marek Polacek wrote: > On Tue, Feb 25, 2020 at 01:27:12PM -0500, Jason Merrill wrote: > > On 2/25/20 12:52 PM, Marek Polacek wrote: > > > On Mon, Feb 24, 2020 at 05:15:45PM -0500, Jason Merrill wrote: > > > > On 2/20/20 11:52 AM, Marek Polacek wrote: > > > > > 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)); > > > > > > > > instead of this, how about casting data_addr to elt_type* before > > > > cp_build_fold_indirect_ref? > > Gotcha. I'm testing the following, OK for 8/9/10 if it passes?
Which it did. > -- >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 | 8 ++++++-- > gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C | 13 +++++++++++++ > 2 files changed, 19 insertions(+), 2 deletions(-) > 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..61ed3aa7e93 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) > { > + /* 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 t = fold_convert (build_pointer_type (elt_type), data_addr); > /* 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); > + init_expr = cp_build_fold_indirect_ref (t); > 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: a71f2193d0df71a86c4743aab22891bb0003112e > -- > Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA > Marek
