https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100079
Bug ID: 100079
Summary: Non-type template parameter, itself a nested template,
rejected with internal error
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mail at lboeger dot de
Target Milestone: ---
The following snippet triggers an internal compiler error.
template <auto value>
struct Foo {
using SomeTypeAlias = int;
Foo()
{}
};
template <class T>
struct Bar {
T value;
constexpr Bar(const T& value)
: value{value}
{}
};
template <int N>
struct Baz {};
constexpr auto baz = Baz<42>{};
const Foo<Bar<Baz<42>>{baz}> test{};
test.cpp: In instantiation of 'struct Foo<Bar<Baz<42> >()>':
test.cpp:6:5: required from 'Foo<value>::Foo() [with auto value = Bar<Baz<42>
>{Baz<42>()}]'
test.cpp:24:35: required from here
test.cpp:3:12: internal compiler error: in finish_member_declaration, at
cp/semantics.c:3237
3 | struct Foo {
| ^
Interestingly, when removing the type alias Foo::SomeTypeAlias, this compiles
as expected. In addition, defaulting the Foo constructor yields a different
diagnostic:
test.cpp: In instantiation of 'struct Foo<Bar<Baz<42> >{Baz<42>()}>':
test.cpp:24:30: required from here
test.cpp:6:5: error: defaulted declaration 'Foo<value>::Foo() [with auto value
= Bar<Baz<42> >{Baz<42>()}]' does not match the expected signature
6 | Foo() = default;
| ^~~
test.cpp:6:5: note: expected signature: 'constexpr Foo<Bar<Baz<42>
>{Baz<42>()}>::Foo()'
These results were produced with gcc-10.2.0_4 on MacOS, but it seems to be the
same in 10.3 and trunk (see https://godbolt.org/z/PexPbq6cf)
