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Add additional test cases and improve span lint

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This commit is contained in:
nahuakang 2021-02-03 19:45:58 +01:00
parent 0f5e71f8f2
commit 78ef0f2f6c
3 changed files with 109 additions and 50 deletions
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47
clippy_lints/src/loops.rs
View file

@ -2034,42 +2034,27 @@ fn check_manual_flatten<'tcx>(
// Prepare the help message
let mut applicability = Applicability::MaybeIncorrect;
let arg_snippet = snippet_with_applicability(
cx,
arg.span,
"..",
&mut applicability,
);
// Determine if `arg` is by reference, an `Iterator`, or implicitly adjusted with `into_iter`
let arg_ty = cx.typeck_results().expr_ty(arg);
let hint = if arg_ty.is_ref() {
if has_iter_method(cx, arg_ty).is_none() {
return;
} else if let ExprKind::AddrOf(_, _, arg_expr) = arg.kind {
format!("{}.iter().flatten()", snippet(cx, arg_expr.span, ".."))
} else {
return;
}
} else if let Some(id) = get_trait_def_id(cx, &paths::ITERATOR) {
let is_iterator = implements_trait(cx, arg_ty, id, &[]);
if is_iterator {
format!("{}.flatten()", arg_snippet)
} else {
format!("{}.into_iter().flatten()", arg_snippet)
}
} else {
return
};
let arg_snippet = make_iterator_snippet(cx, arg, &mut applicability);
span_lint_and_sugg(
span_lint_and_then(
cx,
MANUAL_FLATTEN,
span,
&msg,
"try",
hint,
applicability,
)
|diag| {
let sugg = format!("{}.flatten()", arg_snippet);
diag.span_suggestion(
arg.span,
"try",
sugg,
Applicability::MaybeIncorrect,
);
diag.span_help(
inner_expr.span,
"also remove the `if let` statement in the for loop",
);
}
);
}
}
}

18
tests/ui/manual_flatten.rs
View file

@ -4,8 +4,8 @@ fn main() {
// Test for loop over implicitly adjusted `Iterator` with `if let` expression
let x = vec![Some(1), Some(2), Some(3)];
for n in x {
if let Some(n) = n {
println!("{}", n);
if let Some(y) = n {
println!("{}", y);
}
}
@ -24,12 +24,22 @@ fn main() {
}
}
// Test for loop over an implicit reference
// Note: If `clippy::manual_flatten` is made autofixable, this case will
// lead to a follow-up lint `clippy::into_iter_on_ref`
let z = &y;
for n in z {
if let Ok(n) = n {
println!("{}", n);
}
}
// Test for loop over `Iterator` with `if let` expression
let z = vec![Some(1), Some(2), Some(3)];
let z = z.iter();
for n in z {
if let Some(n) = n {
println!("{}", n);
if let Some(m) = n {
println!("{}", m);
}
}

94
tests/ui/manual_flatten.stderr
View file

@ -1,44 +1,108 @@
error: unnecessary `if let` since only the `Some` variant of the iterator element is used
--> $DIR/manual_flatten.rs:6:5
|
LL | / for n in x {
LL | | if let Some(n) = n {
LL | | println!("{}", n);
LL | for n in x {
| ^ - help: try: `x.into_iter().flatten()`
| _____|
| |
LL | | if let Some(y) = n {
LL | | println!("{}", y);
LL | | }
LL | | }
| |_____^ help: try: `x.into_iter().flatten()`
| |_____^
|
= note: `-D clippy::manual-flatten` implied by `-D warnings`
help: also remove the `if let` statement in the for loop
--> $DIR/manual_flatten.rs:7:9
|
LL | / if let Some(y) = n {
LL | | println!("{}", y);
LL | | }
| |_________^
error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
--> $DIR/manual_flatten.rs:14:5
|
LL | / for n in y.clone() {
LL | for n in y.clone() {
| ^ --------- help: try: `y.clone().into_iter().flatten()`
| _____|
| |
LL | | if let Ok(n) = n {
LL | | println!("{}", n);
LL | | };
LL | | }
| |_____^ help: try: `y.clone().into_iter().flatten()`
| |_____^
|
help: also remove the `if let` statement in the for loop
--> $DIR/manual_flatten.rs:15:9
|
LL | / if let Ok(n) = n {
LL | | println!("{}", n);
LL | | };
| |_________^
error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
--> $DIR/manual_flatten.rs:21:5
|
LL | / for n in &y {
LL | for n in &y {
| ^ -- help: try: `y.iter().flatten()`
| _____|
| |
LL | | if let Ok(n) = n {
LL | | println!("{}", n);
LL | | }
LL | | }
| |_____^ help: try: `y.iter().flatten()`
error: unnecessary `if let` since only the `Some` variant of the iterator element is used
--> $DIR/manual_flatten.rs:30:5
| |_____^
|
LL | / for n in z {
LL | | if let Some(n) = n {
help: also remove the `if let` statement in the for loop
--> $DIR/manual_flatten.rs:22:9
|
LL | / if let Ok(n) = n {
LL | | println!("{}", n);
LL | | }
| |_________^
error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
--> $DIR/manual_flatten.rs:31:5
|
LL | for n in z {
| ^ - help: try: `z.into_iter().flatten()`
| _____|
| |
LL | | if let Ok(n) = n {
LL | | println!("{}", n);
LL | | }
LL | | }
| |_____^ help: try: `z.flatten()`
| |_____^
|
help: also remove the `if let` statement in the for loop
--> $DIR/manual_flatten.rs:32:9
|
LL | / if let Ok(n) = n {
LL | | println!("{}", n);
LL | | }
| |_________^
error: aborting due to 4 previous errors
error: unnecessary `if let` since only the `Some` variant of the iterator element is used
--> $DIR/manual_flatten.rs:40:5
|
LL | for n in z {
| ^ - help: try: `z.flatten()`
| _____|
| |
LL | | if let Some(m) = n {
LL | | println!("{}", m);
LL | | }
LL | | }
| |_____^
|
help: also remove the `if let` statement in the for loop
--> $DIR/manual_flatten.rs:41:9
|
LL | / if let Some(m) = n {
LL | | println!("{}", m);
LL | | }
| |_________^
error: aborting due to 5 previous errors