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From: "nickhuang99 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/104358] Assignable template lambda as function parameter is
 incorrectly reduced to type of "int"
Date: Thu, 03 Feb 2022 20:14:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104358

--- Comment #1 from qingzhe huang <nickhuang99 at hotmail dot com> ---
Sorry about the long description and here is the short version to highlight=
 the
core issue. Given this template function with a templated lambda as paramet=
er:

template<typename T>
using Lambda=3Ddecltype(+[](T){});

template<typename T>
auto foo(T&&, Lambda<T>)->T;



GCC considers the parameter "Lambda<T>" as type "int" which is wrong:

static_assert(is_same_v<decltype(&foo<int>),=20
                 int(*)(int&&, /*"Lambda<T>"*/ int)>);=