fix: derive source scope from syntax node to be transformed

[lowr]

Fixes #14534

When we use PathTransform for associated items of a trait, we have been feeding SemanticsScope for the trait definition to it as source scope. PathTransform uses the source scope to resolve paths in associated items to find which path to transform. In the course of path resolution, the scope is responsible for lowering ast::MacroTypes (because they can be written within a path) using AstIdMap for the scope's HirFileId.

The problem here is that when an associated item is generated by a macro, the scope for the trait is different from the scope for that associated item. The former can only resolve the top-level macros within the trait definition but not the macro calls generated by those top-level macros. We need the latter to resolve such nested macros.

This PR makes sure that we pass SemanticsScope for each associated item we're applying path transformation to.

[Veykril]

So that was the problem
@bors r+

[bors]

📌 Commit 7df5768 has been approved by Veykril

It is now in the queue for this repository.

[bors]

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

1. git checkout fix/nested-macro-in-assoc-item-panic (switch to your branch)
2. git fetch upstream master (retrieve the latest master)
3. git rebase upstream/master -p (rebase on top of it)
4. Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
5. git push self fix/nested-macro-in-assoc-item-panic --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging crates/ide-assists/src/utils.rs
CONFLICT (content): Merge conflict in crates/ide-assists/src/utils.rs
Auto-merging crates/ide-assists/src/handlers/replace_derive_with_manual_impl.rs
CONFLICT (content): Merge conflict in crates/ide-assists/src/handlers/replace_derive_with_manual_impl.rs
Auto-merging crates/ide-assists/src/handlers/add_missing_impl_members.rs
CONFLICT (content): Merge conflict in crates/ide-assists/src/handlers/add_missing_impl_members.rs
Automatic merge failed; fix conflicts and then commit the result.

[lnicola]

@bors r=Veykril

[bors]

📌 Commit d091991 has been approved by Veykril

It is now in the queue for this repository.

[bors]

⌛ Testing commit d091991 with merge c3bab96...

[bors]

☀️ Test successful - checks-actions
Approved by: Veykril
Pushing c3bab96 to master...