https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101227
Bug ID: 101227
Summary: Clang++ fails to instantiate std::optional if nested
type has a non-static data member initializer
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: florin at iucha dot net
Target Milestone: ---
I have reported https://bugs.llvm.org/show_bug.cgi?id=50904 and David suggested
it might be a bug in libstdc++.
GCC11.1 compiles this ok, Clang11 fails:
#include <optional>
class Bar
{
public:
struct Foo
{
int someInt = 3;
};
std::optional<Foo> theFoo;
};
int main()
{
Bar aBar;
aBar.theFoo = std::make_optional<Bar::Foo>();
return 0;
}
---
<source>:18:18: error: no matching function for call to 'make_optional'
aBar.theFoo = std::make_optional<Bar::Foo>();
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/12.0.0/../../../../include/c++/12.0.0/optional:1276:5:
note: candidate template ignored: requirement 'is_constructible_v<Bar::Foo>'
was not satisfied [with _Tp = Bar::Foo, _Args = <>]
make_optional(_Args&&... __args)
^
/opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/12.0.0/../../../../include/c++/12.0.0/optional:1268:5:
note: candidate function template not viable: requires single argument '__t',
but no arguments were provided
make_optional(_Tp&& __t)
^
/opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/12.0.0/../../../../include/c++/12.0.0/optional:1284:5:
note: candidate function template not viable: requires at least argument
'__il', but no arguments were provided
make_optional(initializer_list<_Up> __il, _Args&&... __args)
^
1 error generated.
Compiler returned: 1
