https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109422
Bug ID: 109422
Summary: wrong depth used for template parameter mangling for
lambdas in function signatures
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: richard-gccbugzilla at metafoo dot co.uk
Target Milestone: ---
Testcase:
struct C {
template<typename T>
void f(decltype([](T, auto) { return 0; })) {}
};
void g() { C().f<int>({}); }
GCC mangles f<int> as _ZN1C1fIiEEvDTtlNS_UlT_T_E_EEE -- note that this is
mangling / numbering the lambda directly within C, which is not permitted by
http://itanium-cxx-abi.github.io/cxx-abi/abi.html#closure-types but seems like
the best choice (see https://github.com/itanium-cxx-abi/cxx-abi/issues/165).
But the mangling of the <lambda-sig> as T_T_ is definitely wrong -- two
different template parameters should not be mangled the same. This should
instead be mangled as T_TL__ under
https://github.com/itanium-cxx-abi/cxx-abi/issues/31#issuecomment-528122117
