Fix ICE #3719+#3718 in lint match_ref_pats
Fixes#3719
This conveniently also fixes#3718
The ICE occurs when the match expression was a macro call, where the macro was defined in another file. Since we don't have the ability to reproduce this behavior with our UI tests (AFAIK), I couldn't add a test reproducing this ICE.. However, I added a test which is related to the ICE, to show the new behavior of the lint.
I tested it with the mscheme repo locally and the ICE didn't happen anymore.
r? @matthiaskrgr
Fix ICE #3747
I'm not sure if this was the correct approach.
I don't know if I put tests/ui/crashses/ice-3747.rs in correct place because the test always passed when I ran it with `cargo test`, even without the fix applied.
If I run that test with `env CLIPPY_TESTS=true cargo run --bin clippy-driver -- -L ./target/debug tests/ui/crashes/ice-3747.rs` then the test correctly fails without the fix applied
fixes#3747
Extract diagnostics module and document some functions
This moves the lint building functions from `utils/mod.rs` to their own
`utils/diagnostics.rs` file. Also adds documentation for three of them.
Make needless_range_loop not applicable to structures without iter method
Fixes https://github.com/rust-lang/rust-clippy/issues/3788
Now we will start lint indexed structure only if it has known iter or iter_mut method implemented.
Don't check [print/write]_with_newline on raw strings
Some tests for #3778 and some maybe-not-the-greatest code that passes those tests!
I didn't run `fmt` because a) it doesn't seem to install on nightly for me, and b) on stable it wanted to apply formatting to over 90 files. Happy to make any tweaks though!
I suspect this contribution may require more than just tweaks. I'm still sort of new to rust so it may not be idiomatic, and the specific approach I took feels a little heavy-handed and brittle. I'm happy to make changes with some guidance, or equally happy if this gives a starting place for someone else to do it better :)
Add a lint to warn on `T: Drop` bounds
**What it does:** Checks for generics with `std::ops::Drop` as bounds.
**Why is this bad?** `Drop` bounds do not really accomplish anything.
A type may have compiler-generated drop glue without implementing the
`Drop` trait itself. The `Drop` trait also only has one method,
`Drop::drop`, and that function is by fiat not callable in user code.
So there is really no use case for using `Drop` in trait bounds.
**Known problems:** None.
**Example:**
```rust
fn foo<T: Drop>() {}
```
Fixes#3773
Both regular strings and raw strings can contain literal newlines. This commit
extends the lint to also warn about terminating strings with these.
Behaviour handling for raw strings is also moved into `check_newlines` by
passing in the `is_raw` boolean from `check_tts` as
[suggested](https://github.com/rust-lang/rust-clippy/pull/3781#pullrequestreview-204663732)
Pass tests for #3778, {print,write}_with_newline false positive
This change guards the lint from checking newlines with a sort of complicated
check to see if it's a raw string. Raw strings shouldn't be newline-checked,
since r"\n" is literally \-n, not a newline. I think it's ok not to check for
_literal_ newlines at the end of raw strings, but maybe that's debatable.
I... don't think this code is that great. I wanted to write the check after
`check_tts`, but that was too late -- raw string type info is lost (or I
couldn't find it). Putting it inside `check_tts` feels heavy-duty and the check
itself feels like a brittle reach possibly into places it shouldn't.
Maybe someone can fix this up :)
**What it does:** Checks for generics with `std::ops::Drop` as bounds.
**Why is this bad?** `Drop` bounds do not really accomplish anything.
A type may have compiler-generated drop glue without implementing the
`Drop` trait itself. The `Drop` trait also only has one method,
`Drop::drop`, and that function is by fiat not callable in user code.
So there is really no use case for using `Drop` in trait bounds.
**Known problems:** None.
**Example:**
```rust
fn foo<T: Drop>() {}
```
