Rewrite std_instead_of_core

[bushrat011899]

Objective

• Fixes std_instead_of_core does not detect uses of non-fully qualified items #11159
• Fixes std_instead_of_core creates an invalid fix on stacked imports #12468
• Fixes std_instead_of_core/etc. miss macros #17260
• Alternative/followup to fix [std_instead_of_core]: false positive for multi-imports #17252

Solution

This PR is a major rewrite of std_instead_of_core which reduces allocations and hardens against possible changes to path segment resolution information, such as what is proposed in rust-lang/rust#159760. Instead of relying exclusively on check_path to collect possible lint points, we primarily rely on check_item for use statements. check_path is still used to catch instances such as std::boxed::Box::new(123), but such cases will contain resolution information for the full path, as the path is not shared across multiple items.

Lintcheck Interpretation

alloc_instead_of_core

• Vast majority of additions come from linting cases like fmt::Result when a crate does use std::fmt;. This is intended.

std_instead_of_alloc

• Additions and changes come from sync::{Arc, Mutex} and catching crate renames (extern crate std as alloc, etc.)
• Removal comes from crate renaming.

std_instead_of_core

• Some additions come from non-FQN paths such as hash::Hash.
• Further additions come from splitting incorrectly merged suggestion lints into multiple help emissions.
• Some removals come from catching crate renames (extern crate core as std, etc.)
• Other removals come from improper merges, such as std::fmt::{self, Debug} (while Debug is defined in core, std::fmt::self is alloc::fmt, so this cannot be a merged suggestion.
• Majority of changes come from fixing improper merges.
• Some changes come from macros having the first or the last call site linted to the user swapped.

---

Please write a short comment explaining your change (or "none" for internal only changes)

changelog: [std_instead_of_core], [std_instead_of_alloc], [alloc_instead_of_core]: fix false positive suggestions for multi-imports
changelog: [std_instead_of_core], [std_instead_of_alloc], [alloc_instead_of_core]: consider crate renames
changelog: [std_instead_of_core], [std_instead_of_alloc], [alloc_instead_of_core]: include relative paths
changelog: [std_instead_of_core], [std_instead_of_alloc], [alloc_instead_of_core]: include macros

[github-actions]

Lintcheck changes for b37f793

Lint	Added	Removed	Changed
clippy::alloc_instead_of_core	2465	0	0
clippy::std_instead_of_alloc	10	1	13
clippy::std_instead_of_core	116	12	18

This comment will be updated if you push new changes

[rustbot]

r? @llogiq

rustbot has assigned @llogiq.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: 8 candidates
• 8 candidates expanded to 8 candidates
• Random selection from Jarcho, llogiq, samueltardieu

[bushrat011899]

r? Jarcho

Please feel free to reverse this! I'm assigning it to you since this is an alternative to #17252 and based on your feedback to me, so I feel you'd be most appropriate to review. Again, thanks for all your help so far!

[oli-obk]

if you store this path in the ItemContext, you should be able to still get the resolutions from that after rust-lang/rust#159760 (comment)

View changes since the review

[bushrat011899]

I think that's exactly right, but I've taken this experience as an opportunity to redo this PR to be much simpler and just directly store the first and last PathSegments. As long as one contains the resolution data for the first segment, that can be used for all lint points sharing that segment.

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[Jarcho]

You beat me to finishing my first review by a few hours (I had it mostly typed up yesterday). You ended up doing one of the major things I was pointing out so that's cool.