#5626: lint iterator.map(|x| x)

[theo-lw]

changelog: adds a new lint for iterator.map(|x| x) (see #5626)

The code also lints for result.map(|x| x) and option.map(|x| x). Also, I'm not sure if I'm checking for type adjustments correctly and I can't think of an example where .map(|x| x) would apply type adjustments.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @matthiaskrgr (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

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[bors]

☔ The latest upstream changes (presumably #5378) made this pull request unmergeable. Please resolve the merge conflicts.

[matthiaskrgr]

I'm wondering if .map(std::convert::identity) (docs) should lint as well.

[bors]

☔ The latest upstream changes (presumably #5279) made this pull request unmergeable. Please resolve the merge conflicts.

[matthiaskrgr]

Could you please rebase and remove the merge commits?

[theo-lw]

Could you please rebase and remove the merge commits?

Done. There's still a merge at the end to get rid of the merge conflict though. Also just asking because I don't know git that well, is there a reason why those merge commits aren't wanted?

[matthiaskrgr]

AFAIK we follow rustcs no-merge policy https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#pull-requests

edit: Alternatively I could squash-merge the entire pr as a single commit.

[flip1995]

@wangtheo If you have difficulties with rebasing, we can do this for you. In fact, I pushed a branch on my fork, where I squashed this PR in one commit: https://github.com/flip1995/rust-clippy/tree/issue-5626

[theo-lw]

AFAIK we follow rustcs no-merge policy https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#pull-requests

edit: Alternatively I could squash-merge the entire pr as a single commit.

Oh that's interesting, I'll keep that in mind.

@wangtheo If you have difficulties with rebasing, we can do this for you. In fact, I pushed a branch on my fork, where I squashed this PR in one commit: https://github.com/flip1995/rust-clippy/tree/issue-5626

I tried rebasing again and I think I managed to get rid of the merge commits 😃

Also it looks like the branch isn't building and I'm not too sure why.

[flip1995]

I think a squash commit would be reasonable here. (There's still one unrelated commit.)

How to squash:

git rebase -i upstream/master  # assuming upstream is the remote of the rust-lang/rust-clippy repo
# editor will open
# change pick -> reword in the first line
# change pick -> fixup in every other line
# save and close editor
# a new editor instance will open, where you can adjust the commit message

Also it looks like the branch isn't building and I'm not too sure why.

Don't worry about that, this will be fixed in another PR (you may have to rebase after that though)

[theo-lw]

I think a squash commit would be reasonable here. (There's still one unrelated commit.)

How to squash:

git rebase -i upstream/master  # assuming upstream is the remote of the rust-lang/rust-clippy repo
# editor will open
# change pick -> reword in the first line
# change pick -> fixup in every other line
# save and close editor
# a new editor instance will open, where you can adjust the commit message

Also it looks like the branch isn't building and I'm not too sure why.

Don't worry about that, this will be fixed in another PR (you may have to rebase after that though)

Followed your instructions and squashed the commit, thanks for the help 😃

[flip1995]

@bors r+

[bors]

📌 Commit 40ee620 has been approved by flip1995

[bors]

🌲 The tree is currently closed for pull requests below priority 10, this pull request will be tested once the tree is reopened

[flip1995]

@bors treeclosed-

[bors]

⌛ Testing commit 40ee620 with merge fda4916...

[bors]

💔 Test failed - checks-action_test

[matthiaskrgr]

   Compiling clippy_lints v0.0.212 (/home/runner/work/rust-clippy/rust-clippy/clippy_lints)
error[E0023]: this pattern has 3 fields, but the corresponding tuple variant has 4 fields
    --> clippy_lints/src/map_identity.rs:64:16
     |
64   |         if let ExprKind::MethodCall(ref method, _, ref args) = expr.kind;
     |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected 4 fields, found 3

error: aborting due to previous error

[matthiaskrgr]

Thanks!
@bors r+

[bors]

📌 Commit fb4f9a0 has been approved by matthiaskrgr

[bors]

⌛ Testing commit fb4f9a0 with merge 583d644...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: matthiaskrgr
Pushing 583d644 to master...