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c++: Fix value-init crash in template [PR93676]

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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.
This commit is contained in:
Marek Polacek 2020-02-19 15:59:33 -05:00
parent 8ce13842b5
commit 38e1002657
4 changed files with 29 additions and 2 deletions
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5
gcc/cp/ChangeLog
View file

@ -1,3 +1,8 @@
2020-02-26 Marek Polacek <polacek@redhat.com>
PR c++/93676 - value-init crash in template.
* init.c (build_new_1): Don't call build_vec_init in a template.
2020-02-26 Marek Polacek <polacek@redhat.com>
PR c++/93862 - ICE with static_cast when converting from int[].

8
gcc/cp/init.c
View file

@ -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,

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2020-02-26 Marek Polacek <polacek@redhat.com>
PR c++/93676 - value-init crash in template.
* g++.dg/cpp0x/nsdmi-template19.C: New test.
2020-02-26 Marek Polacek <polacek@redhat.com>
PR c++/93862 - ICE with static_cast when converting from int[].

13
gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C Normal file
View file

@ -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;