Handles cases of `.collect().len()`, `.collect().is_empty()`, and
`.collect().contains()`. This lint is intended to be generic enough to
be added to at a later time with other similar patterns that could be
optimized.
Closes#3034
Make explicit_iter_loop and explicit_into_iter_loop allow-by-default, so
that people can turn them on if they want to enforce that style; avoid
presenting them as *the* idiomatic Rust style, rather than just *a* style.
This includes the type name, so is clear, and may be necessary.
There doesn't seem to be an obviously cleaner way to pull out the
literal text of the named type here.
Fixes#2879
This is a follow-up to #2951 that extends the logic to allow for
returning references inside structs/enums/unions. This was a simple
oversight in the first version and it's surprisingly easy to handle.
Currently this code will trigger `trivally_copy_pass_by_ref`:
```
struct OuterStruct {
field: [u8; 8],
}
fn return_inner(outer: &OuterStruct) -> &[u8] {
&outer.field
}
```
If we change the `outer` to be pass-by-value it will not live long
enough for us to return the reference. The above example is trivial but
I've hit this in real code that either returns a reference to either the
argument or in to `self`.
This suppresses the `trivally_copy_pass_by_ref` lint if we return a
reference and it has the same lifetime as the argument. This will likely
miss complex cases with multiple lifetimes bounded by each other but it
should cover the majority of cases with little effort.
The macro always negates the result of the given comparison in its
internal check which automatically triggered the lint. As its an
external macro there was no chance to do anything about it which lead
to a white listing of all external macros to prevent further issues.
This commit removes the logic in this PR that linted out-of-bounds constant `usize` indexing on arrays. That case is already handled by rustc's `const_err` lint. Beyond removing the linting logic, the test file and its associated stderr were updated to verify that const `usize` indexing operations on arrays are no longer handled by this `indexing_slicing` lint.
In this commit tests were added to ensure that tests with a `const` index behaved as expected.
In order to minimize the changes to the test's corresponding `stderr`, the tests were appended to
the end of the file.
This commit contains a few changes. In an attempt to clarify which test cases should and should not produce stderr it became clear that some cases were being handled incorrectly. In order to address these test cases, a minor re-factor was made to the linting logic itself.
The re-factor was driven by edge case handling including a need for additional match conditions for `ExprCall` (`&x[0..=4]`) and `ExprBinary` (`x[1 << 3]`). Rather than attempt to account for each potential `Expr*` the code was re-factored into simply "if ranged index" and an "otherwise" conditions.
The changes reflected in this commit (requested in PR #2790) are as follows:
- Extended `INDEXING_SLICING` documentation to include the array type so that it is clearer when indexing operations are allowed.
- Variable `ty` defined identically in multiple scopes was moved to an outer scope so it's only defined once.
- Added a missing return statement to ensure only one lint is triggered by a scenario.
- Prettified match statement with a `let` clause. (I learned something new!)
- Added `&x[5..].iter().map(|x| 2 * x).collect::<Vec<i32>>()` and `&x[2..].iter().map(|x| 2 * x).collect::<Vec<i32>>()` to the test cases. The first _should trigger the lint/stderr_ and the second _should not_.
The changes reflected in this commit are as follows:
- Revised `IndexingSlicingPass` struct name to IndexingSlicing for consistency with the rest of the code base.
- Revised match arm condition to use `(..)` shorthand in favor of `(_, _, _)`.
- Restored a couple telling variable names.
- Calls to `cx.span_lint` were revised to use `utils::span_help_and_lint`.
- Took a stab at refactoring some generalizable calls to `utils::span_help_and_lint` to minimize duplicate code.
- Revised INDEXING_SLICING declaration to pedantic rather than restriction.
- Added `&x[0..].get(..3)` to the test cases.
This commit renames instances of `array_indexing` to `indexing_slicing` and moves the `indexing_slicing` lint to the `clippy_pedantic` group. The justification for this commit's changes are detailed in the previous commit's message.
