Add Collapsible match lint
changelog: Add collapsible_match lint
Closes#1252Closes#2521
This lint finds nested `match` or `if let` patterns that can be squashed together. It is designed to be very conservative to only find cases where merging the patterns would most likely reduce cognitive complexity.
Example:
```rust
match result {
Ok(opt) => match opt {
Some(x) => x,
_ => return,
}
_ => return,
}
```
to
```rust
match result {
Ok(Some(x)) => x,
_ => return,
}
```
These criteria must be met for the lint to fire:
* The inner match has exactly 2 branches.
* Both the outer and inner match have a "wild" branch like `_ => ..`. There is a special case for `None => ..` to also be considered "wild-like".
* The contents of the wild branches are identical.
* The binding which "links" the matches is never used elsewhere.
Thanks to the hir, `if let`'s are easily included with this lint since they are desugared into equivalent `match`'es.
I think this would fit into the style category, but I would also understand changing it to pedantic.
Enhance `redundant_pattern_matching` to also lint on `std::net::IpAddr`
Follow-up to #6339
r? `@ebroto`
(note: also contains a small cleanup of the other ui tests)
changelog: Enhance [`redundant_pattern_matching`] to also lint on `std::net::IpAddr`
Added known problem to comparison_chain docs
changelog: Added documentation to comparison_chain that explains a possible performance penalty, according to issue #5354
This is my first PR, I hope everything has been done correctly.
Fixes#5354
Add suspicious_operation_groupings lint
This is my (<del> currently WIP </del>) attempt to close#6039.
changelog: Added `suspicious_operation_groupings` lint.
run `cargo dev new_lint --category correctness --name suspicious_chained_operators --pass early`
add (currently failing) tests for suspicious_chained_operators
add some tests to answer a question that came up during implementation
write usage code for functions we'll need to find or create
Complete left-right tracking TODO
get it compiling with several `todo!` invocations.
refactor to a set of incomplete functions that don't expect to be able to edit a `Span`
create placeholder for `suggestion_with_swapped_ident` function and correct some comments
add `inside_larger_boolean_expression` test
fill out `get_ident` and `suggestion_with_swapped_ident`
Implementi the `IdentIter`
start on implementing the `IdentIter`
handle the `ExprKind::Path` case in `IdentIter`
on second thought, make the iterator type dynamic so we don't need an explicit type for each one we will need
handle `ExprKind::MacCall` in `IdentIter`
Try handling `box x` expressions
restructure `IdentIter`
set `self.done` when returning `None`
Handle `ExprKind::Array`
reduce duplication with a macro that we expect to use several more times
handle ExprKind::Call
add `new_p` convenience method
handle `MethodCall`
handle `Tup` and `Binary`
handle `Unary`
simplify by not returning an additional `Expr` from the `IdentIter`
add cross product test against false positives
rename suspicious_chained_operators to suspicious_operation_groupings within files
For the record, the exact commands run were:
find . -type f -name "*.md" -exec sed -i 's/suspicious_chained_operators/suspicious_operation_groupings/g' {} +
find . -type f -name "*.rs" -exec sed -i 's/suspicious_chained_operators/suspicious_operation_groupings/g' {} +
find . -type f -name "*.rs" -exec sed -i 's/SUSPICIOUS_CHAINED_OPERATORS/SUSPICIOUS_OPERATION_GROUPINGS/g' {} +
find . -type f -name "*.rs" -exec sed -i 's/SuspiciousChainedOperators/SuspiciousOperationGroupings/g' {} +
Also:
rename file to match module name
rename test file to match lint name
start implementing `IdentDifference` creation
add `IdentIter` utility
use `ident_iter::IdentIter`
fix bug in `suggestion_with_swapped_ident`
add `inside_if_statements` test
implement `Add` `todo`s
register `SuspiciousOperationGroupings` lint pass
fill in `chained_binops`, and fill in a stopgap version of `ident_difference_expr`, but then notice that the lint does not seem to ever be run in the tests
run `cargo dev update_lints` and not that the `suspicious_operation_groupings` lint still does not seem to be run
fix base index incrementing bug
fix paired_identifiers bug, and remove ident from `Single`
change help prefix and note our first successful lint messages!
add odd_number_of_pairs test
get the `non_boolean_operators` test passing, with two copies of the error message
extract `is_useless_with_eq_exprs` so we can know when `eq_op` will already handle something
add `not_caught_by_eq_op` tests since `s1.b * s1.b` was (reasonably) not caught by `eq_op`
cover the case where the change should be made on either side of the expression with `not_caught_by_eq_op` tests
produce the expected suggestion on the `not_caught_by_eq_op_middle_change_left` test
confirm that the previous tests still pass and update references
fix early continue bug and get `not_caught_by_eq_op_middle_change_right` passing
note that `not_caught_by_eq_op_start` already passes
fix bugs based on misunderstanding of what `Iterator::skip` does, and note that `not_caught_by_eq_op_end` now passes
add several parens tests and make some of them pass
handle parens inside `chained_binops_helper` and note that this makes several tests pass
get `inside_larger_boolean_expression_with_unsorted_ops` test passing by extracting out `check_same_op_binops` function
also run `cargo dev fmt`
note that `inside_function_call` already passes
add another `if_statement` test
remove the matching op requirement, making `inside_larger_boolean_expression_with_unsorted_ops` pass
prevent non-change suggestions from being emitted
get the `Nested` tests passing, and remove apparently false note about eq_op
add a test to justify comment in `ident_difference_expr_with_base_location` but find that the failure mode seems different than expected
complete `todo` making `do_not_give_bad_suggestions_for_this_unusual_expr` pass and add some more tests that already pass
add test to `eq_op`
note that `inside_fn_with_similar_expression` already passes
fix `inside_an_if_statement` and note that it already passes
attempt to implement if statement extraction and notice that we don't seem to handle unary ops correctly
add `maximum_unary_minus_right_tree` test and make it pass
add two tests and note one of them passes
filter out unary operations in several places, and find that the issue seems to be that we don't currently recognize the error in `multiple_comparison_types_and_unary_minus` even so.
remove filtering that was causing bad suggestions
remove tests that were deemed too much for now
run `cargo dev fmt`
correct eq_op post-merge
fill out the description and delete debugging code
run `cargo dev update_lints`
update eq_op references
add parens to work around rustfmt issue #3666 and run rustfmt
https://github.com/rust-lang/rustfmt/issues/3666#issuecomment-714612257
update references after formatting
fix dogfood issues
fix multi-cursor edit
fix missed dogfood error
fix more dogfood pedantic issues, including function length
even more nesting
insert hidden definition of Vec3 so docs compile
add spaces to second struct def
reword test description comment
Co-authored-by: llogiq <bogusandre@gmail.com>
add local `use BinOpKind::*;`
Apply suggestions from code review
Co-authored-by: llogiq <bogusandre@gmail.com>
switch `SUSPICIOUS_OPERATION_GROUPINGS` to a style lint
run `cargo dev update_lints`
put both usages of `op_types` in the same closure to satisfy `borrowck`
fix compile error
rustc_ast currently has a few dependencies on rustc_lexer. Ideally, an AST
would not have any dependency its lexer, for minimizing unnecessarily
design-time dependencies. Breaking this dependency would also have practical
benefits, since modifying rustc_lexer would not trigger a rebuild of rustc_ast.
This commit does not remove the rustc_ast --> rustc_lexer dependency,
but it does remove one of the sources of this dependency, which is the
code that handles fuzzy matching between symbol names for making suggestions
in diagnostics. Since that code depends only on Symbol, it is easy to move
it to rustc_span. It might even be best to move it to a separate crate,
since other tools such as Cargo use the same algorithm, and have simply
contain a duplicate of the code.
This changes the signature of find_best_match_for_name so that it is no
longer generic over its input. I checked the optimized binaries, and this
function was duplicated at nearly every call site, because most call sites
used short-lived iterator chains, generic over Map and such. But there's
no good reason for a function like this to be generic, since all it does
is immediately convert the generic input (the Iterator impl) to a concrete
Vec<Symbol>. This has all of the costs of generics (duplicated method bodies)
with no benefit.
Changing find_best_match_for_name to be non-generic removed about 10KB of
code from the optimized binary. I know it's a drop in the bucket, but we have
to start reducing binary size, and beginning to tame over-use of generics
is part of that.
Change `redundant_pattern_matching` to also lint `std::task::Poll`
`reduntant_pattern_matching` currently lints pattern matching on `Option` and `Result` where the `is_variant` utility methods could be used instead: `is_some`, `is_none`, `is_ok`, `is_err`. This PR extends this behaviour to `std::task::Poll`, suggesting the methods `is_pending` and `is_ready`.
Motivation: The current description of `redundant_pattern_matching` mentions
> It's more concise and clear to just use the proper utility function
which in my mind applies to `Poll` as well.
changelog: Enhance [`redundant_pattern_matching`] to also lint on `std::task::Poll`
