[Bug c++/94894] New: Premature instantiation of conversion function template during overload resolution
ppalka at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Thu Apr 30 18:10:07 GMT 2020
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94894
Bug ID: 94894
Summary: Premature instantiation of conversion function
template during overload resolution
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ppalka at gcc dot gnu.org
Target Milestone: ---
The following testcase was reduced from a build failure with GCC 10 when
compiling LLVM.
When considering the overload candidate 'void f(int&)' for the overloaded call
'f(S{})', we try to build up a conversion sequence from 'S' to 'int&' that goes
through the conversion operator template with T=int. In doing so we
instantiate the conversion operator template, which triggers an instantiation
of F<int>::k which triggers a hard error.
$ cat testcase.C
template <typename T, bool B = false>
struct F
{
static_assert(B);
};
struct S
{
template <typename T, int = F<T>::k> operator T();
};
void f(int&);
void f(S);
void foo()
{
f(S{});
}
$ g++ testcase.C
testcase.C: In instantiation of ‘struct F<int, false>’:
testcase.C:9:37: required by substitution of ‘template<class T, int
<anonymous> > S::operator T() [with T = int; int <anonymous> = <missing>]’
testcase.C:18:6: required from here
testcase.C:4:17: error: static assertion failed
4 | static_assert(B);
| ^
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