Emit a diagnostic note at the class declaration when the method definition does not match any declaration.

[hokein]

Considering the follow case:

template <class T>
class FooBar {
  double Foo();
};

template <class T>
double FooBar<T>::Bar() { return 0.0; }

Currently, Clang only emits the error out-of-line definition of 'Bar' does not match any declaration at the Bar definition. It would be helpful to also emit a note pointing to the FooBar class declaration (GCC already does this).

See https://godbolt.org/z/GG8zvvzaP

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Haojian Wu (hokein)

Considering the follow case:

template <class T>
class FooBar {
  double Foo();
};

template <class T>
double FooBar<T>::Bar() { return 0.0; }

Currently, Clang only emits the error out-of-line definition of 'Bar' does not match any declaration at the Bar definition. It would be helpful to also emit a note pointing to the FooBar class declaration (GCC already does this).

See https://godbolt.org/z/GG8zvvzaP

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Haojian Wu (hokein)

Considering the follow case:

template <class T>
class FooBar {
  double Foo();
};

template <class T>
double FooBar<T>::Bar() { return 0.0; }

Currently, Clang only emits the error out-of-line definition of 'Bar' does not match any declaration at the Bar definition. It would be helpful to also emit a note pointing to the FooBar class declaration (GCC already does this).

See https://godbolt.org/z/GG8zvvzaP

[shafik]

@hokein since you labelled this a good first issue, it may be helpful to point out the diagnostic id and where the diagnostic is being emitted to help someone new get started.