disallowed_methods: Support functions in addition to methods
## Context:
Hey all! I have a particular use case where I'd like to ban certain functions in a code base I work on. For example, I want to ban `Instant::now()` (among others) as we have a time service for mocking time in deterministic simulation tests. Obviously, it doesn't make sense to include a lint like this for all clippy users. Imagine my excitement when I spotted the new `disallowed_methods` lint in clippy--perfect! Unfortunately, after playing around with it for a bit, I was frustrated to realize that it didn't support functions like `Instant::now()`, so I've added support for them in this PR.
It might also make sense to rename the lint from `disallowed_methods` -> `disallowed_functions`, though I've held off from including that rename in this change, since I'm unsure of clippy's breaking change policy.
## Change
Support functions in addition to methods. In other words, support:
`disallowed_methods = ["alloc::vec::Vec::new"]` (a function) in addition to
`disallowed_methods = ["alloc::vec::Vec::leak"]` (a method).
Improve the documentation to clarify that users must specify the full qualified path for each disallowed function, which can be confusing for reexports. Include an example `clippy.toml`.
Simplify the actual lint pass so we can reuse `utils::fn_def_id`.
changelog: disallowed_method: Now supports functions in addition to methods
Add new lint `filter_map_identity`
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This commit adds a new lint named filter_map_identity.
This lint is the same as `flat_map_identity` except that it checks for the usage of `filter_map`.
---
Closes#6643
changelog: Added a new lint: `filter_map_identity`
Adds a new lint that checks if there is a semicolon on the last block statement if it returns nothing
changelog: Added a new lint: `SEMICOLON_IF_NOTHING_RETURNED`
fixes#6467
Adds the `SEMICOLON_IF_NOTHING_RETURNED` lint and therefore closes#6467.
Cleanup path-to-local checks
changelog: none
It seemed like too much ceremony going on to check if an expression matches a variable. So I created two util functions `path_to_local(Expr) -> Option<HirId>` and `path_to_local_id(Expr, HirId) -> bool` to make this easier, and used them wherever applicable.
I changed logic in a few places to use `HirId` instead of `Symbol` where it was easy to do so. I believe this is more correct and may even fix some bugs.
I also removed some calls to `qpath_res`. This is not needed if you are only looking for a `Res::Local`.
As a note, I wanted to name the util functions in a way that encourages understanding of the HIR.
This commit adds a new lint named `filter_map_identity`. This lint is
the same as `flat_map_identity` except that it checks for `filter_map`.
Closes#6643
In other words, support:
`disallowed_methods = ["alloc::vec::Vec::new"]` (a free function) in
addition to
`disallowed_methods = ["alloc::vec::Vec::leak"]` (a method).
Improve the documentation to clarify that users must specify the full
qualified path for each disallowed function, which can be confusing for
reexports. Include an example `clippy.toml`.
Simplify the actual lint pass so we can reuse `utils::fn_def_id`.
New Lint: Manual Flatten
This is a draft PR for [Issue 6564](https://github.com/rust-lang/rust-clippy/issues/6564).
r? `@camsteffen`
- \[x] Followed [lint naming conventions][lint_naming]
- \[x] Added passing UI tests (including committed `.stderr` file)
- \[x] `cargo test` passes locally
- \[x] Executed `cargo dev update_lints`
- \[x] Added lint documentation
- \[x] Run `cargo dev fmt`
---
*Please write a short comment explaining your change (or "none" for internal only changes)*
changelog: Add new lint [`manual_flatten`] to check for loops over a single `if let` expression with `Result` or `Option`.
Fix let_and_return false positive
The issue:
See this Rust playground link: https://play.rust-lang.org/?edition=2018&gist=12cb5d1e7527f8c37743b87fc4a53748
Run the above with clippy to see the following warning:
```
warning: returning the result of a `let` binding from a block
--> src/main.rs:24:5
|
23 | let value = Foo::new(&x).value();
| --------------------------------- unnecessary `let` binding
24 | value
| ^^^^^
|
= note: `#[warn(clippy::let_and_return)]` on by default
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_and_return
help: return the expression directly
|
23 |
24 | Foo::new(&x).value()
|
```
Implementing the suggested fix, removing the temporary let binding,
yields a compiler error:
```
error[E0597]: `x` does not live long enough
--> src/main.rs:23:14
|
23 | Foo::new(&x).value()
| ---------^^-
| | |
| | borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
24 | }
| -
| |
| `x` dropped here while still borrowed
| ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `Foo`
|
= note: the temporary is part of an expression at the end of a block;
consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
|
23 | let x = Foo::new(&x).value(); x
| ^^^^^^^ ^^^
```
The fix:
Of course, clippy looks like it should already handle this edge case;
however, it appears `utils::fn_def_id` is not returning a `DefId` for
`Foo::new`. Changing the `qpath_res` lookup to use the child Path
`hir_id` instead of the parent Call `hir_id` fixes the issue.
changelog: none
Do not lint when range is completely included into another one
This fix has been developed following this [comment](https://github.com/rust-lang/rust-clippy/issues/5986#issuecomment-703313548).
So this will be linted:
```
|----------|
|-----------|
```
Now this won't be linted:
```
|---|
|--------------------|
```
and this will still lint:
```
|--------|
|--------------|
```
Fixes: #5986
changelog: Fix FPs in match_overlapping_arm, when first arm is completely included in second arm
The issue:
See this Rust playground link: https://play.rust-lang.org/?edition=2018&gist=12cb5d1e7527f8c37743b87fc4a53748
Run the above with clippy to see the following warning:
```
warning: returning the result of a `let` binding from a block
--> src/main.rs:24:5
|
23 | let value = Foo::new(&x).value();
| --------------------------------- unnecessary `let` binding
24 | value
| ^^^^^
|
= note: `#[warn(clippy::let_and_return)]` on by default
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_and_return
help: return the expression directly
|
23 |
24 | Foo::new(&x).value()
|
```
Implementing the suggested fix, removing the temporary let binding,
yields a compiler error:
```
error[E0597]: `x` does not live long enough
--> src/main.rs:23:14
|
23 | Foo::new(&x).value()
| ---------^^-
| | |
| | borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
24 | }
| -
| |
| `x` dropped here while still borrowed
| ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `Foo`
|
= note: the temporary is part of an expression at the end of a block;
consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
|
23 | let x = Foo::new(&x).value(); x
| ^^^^^^^ ^^^
```
The fix:
Of course, clippy looks like it should already handle this edge case;
however, it appears `utils::fn_def_id` is not returning a `DefId` for
`Foo::new`. Changing the `qpath_res` lookup to use the child Path
`hir_id` instead of the parent Call `hir_id` fixes the issue.
Improve safety of `LateContext::qpath_res`
This is my first rustc code change, inspired by hacking on clippy!
The first change is to clear cached `TypeckResults` from `LateContext` when visiting a nested item. I took a hint from [here](5e91c4ecc0/compiler/rustc_privacy/src/lib.rs (L1300)).
Clippy has a `qpath_res` util function to avoid a possible ICE in `LateContext::qpath_res`. But the docs of `LateContext::qpath_res` promise no ICE. So this updates the `LateContext` method to keep its promises, and removes the util function.
Related: rust-lang/rust-clippy#4545
CC ````````````@eddyb```````````` since you've done related work
CC ````````````@flip1995```````````` FYI
