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redundant_closure_call - don't lint when used more than once

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This commit is contained in:
Tim Nielens 2020-07-14 20:27:25 +02:00
parent 8cf4219c16
commit c720d823e1
3 changed files with 47 additions and 22 deletions
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40
clippy_lints/src/misc_early.rs
View File

@ -14,6 +14,7 @@ use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::symbol::Ident;
declare_clippy_lint! {
/// **What it does:** Checks for structure field patterns bound to wildcards.
@ -493,6 +494,29 @@ impl EarlyLintPass for MiscEarlyLints {
}
fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
fn count_closure_usage(block: &Block, ident: &Ident) -> usize {
struct ClosureUsageCount<'ast> {
ident: &'ast Ident,
count: usize,
};
impl<'ast> Visitor<'ast> for ClosureUsageCount<'ast> {
fn visit_expr(&mut self, expr: &'ast Expr) {
if_chain! {
if let ExprKind::Call(ref closure, _) = expr.kind;
if let ExprKind::Path(_, ref path) = closure.kind;
if self.ident == &path.segments[0].ident;
then {
self.count += 1;
}
}
walk_expr(self, expr);
}
}
let mut closure_usage_count = ClosureUsageCount { ident, count: 0 };
closure_usage_count.visit_block(block);
closure_usage_count.count
}
for w in block.stmts.windows(2) {
if_chain! {
if let StmtKind::Local(ref local) = w[0].kind;
@ -503,15 +527,15 @@ impl EarlyLintPass for MiscEarlyLints {
if let ExprKind::Assign(_, ref call, _) = second.kind;
if let ExprKind::Call(ref closure, _) = call.kind;
if let ExprKind::Path(_, ref path) = closure.kind;
if ident == path.segments[0].ident;
if count_closure_usage(block, &ident) == 1;
then {
if ident == path.segments[0].ident {
span_lint(
cx,
REDUNDANT_CLOSURE_CALL,
second.span,
"Closure called just once immediately after it was declared",
);
}
span_lint(
cx,
REDUNDANT_CLOSURE_CALL,
second.span,
"Closure called just once immediately after it was declared",
);
}
}
}

15
tests/ui/redundant_closure_call.rs
View File

@ -8,14 +8,21 @@ fn main() {
k = (|a, b| a * b)(1, 5);
let closure = || 32;
i = closure();
// don't lint here, the closure is used more than once
let closure = |i| i + 1;
i = closure(3);
i = closure(4);
// lint here
let redun_closure = || 1;
i = redun_closure();
// the lint is applicable here but the lint doesn't support redefinition
let redefined_closure = || 1;
i = redefined_closure();
let redefined_closure = || 2;
i = redefined_closure();
#[allow(clippy::needless_return)]
(|| return 2)();
(|| -> Option<i32> { None? })();

14
tests/ui/redundant_closure_call.stderr
View File

@ -1,17 +1,11 @@
error: Closure called just once immediately after it was declared
--> $DIR/redundant_closure_call.rs:12:5
--> $DIR/redundant_closure_call.rs:18:5
|
LL | i = closure();
| ^^^^^^^^^^^^^
LL | i = redun_closure();
| ^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::redundant-closure-call` implied by `-D warnings`
error: Closure called just once immediately after it was declared
--> $DIR/redundant_closure_call.rs:15:5
|
LL | i = closure(3);
| ^^^^^^^^^^^^^^
error: Try not to call a closure in the expression where it is declared.
--> $DIR/redundant_closure_call.rs:7:17
|
@ -24,5 +18,5 @@ error: Try not to call a closure in the expression where it is declared.
LL | k = (|a, b| a * b)(1, 5);
| ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors
error: aborting due to 3 previous errors