| Issue |
184083
|
| Summary |
[clang-tidy] `readability-redundant-typename` false positive on required `typename` in template argument
|
| Labels |
clang-tidy,
false-positive
|
| Assignees |
|
| Reporter |
tarun-t
|
### Description
`readability-redundant-typename` flags `typename` as redundant in a context where both GCC and Clang require it — a dependent type used as a template argument to a class template. Removing `typename` as suggested causes a hard compiler error on both compilers.
### Reproducer
```cpp
#include <unordered_map>
enum class Mode { A, B };
template<Mode M>
struct Foo {
using Bar = int;
static std::unordered_map<int, typename Foo<M>::Bar> create();
};
template<Mode M>
std::unordered_map<int, typename Foo<M>::Bar> Foo<M>::create() { return {}; }
template struct Foo<Mode::A>;
# clang-tidy flags typename as redundant:
$ clang-tidy-22 test.cpp --checks='-*,readability-redundant-typename' -- -std=c++26
# warning: redundant 'typename' [readability-redundant-typename]
# But removing typename causes a compiler error on both:
$ clang++-22 -std=c++26 -c test.cpp
# error: template argument for template type parameter must be a type; did you forget 'typename'?
$ g++-15 -std=c++26 -c test.cpp
# error: type/value mismatch at argument 2 in template parameter list
Expected behavior
No warning — typename is required here because the dependent type appears as a template argument, which is not a context where C++23 made typename optional.
Version
Ubuntu clang version 22.1.1
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