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Auto merge of #5800 - montrivo:bugfix/redundant_closure, r=matthiaskrgr

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redundant_closure_call - don't lint when used more than once

Fixes #3354.

changelog: fix redundant_closure_call false positive when closure called more than once
This commit is contained in:
bors 2020-07-19 22:54:29 +00:00
commit 942e0e6fac
10 changed files with 233 additions and 146 deletions
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9
clippy_lints/src/lib.rs
View file

@ -276,6 +276,7 @@ mod ptr_offset_with_cast;
mod question_mark;
mod ranges;
mod redundant_clone;
mod redundant_closure_call;
mod redundant_field_names;
mod redundant_pub_crate;
mod redundant_static_lifetimes;
@ -702,7 +703,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&misc_early::DOUBLE_NEG,
&misc_early::DUPLICATE_UNDERSCORE_ARGUMENT,
&misc_early::MIXED_CASE_HEX_LITERALS,
&misc_early::REDUNDANT_CLOSURE_CALL,
&misc_early::REDUNDANT_PATTERN,
&misc_early::UNNEEDED_FIELD_PATTERN,
&misc_early::UNNEEDED_WILDCARD_PATTERN,
@ -759,6 +759,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&ranges::RANGE_ZIP_WITH_LEN,
&ranges::REVERSED_EMPTY_RANGES,
&redundant_clone::REDUNDANT_CLONE,
&redundant_closure_call::REDUNDANT_CLOSURE_CALL,
&redundant_field_names::REDUNDANT_FIELD_NAMES,
&redundant_pub_crate::REDUNDANT_PUB_CRATE,
&redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES,
@ -1018,6 +1019,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_early_pass(|| box int_plus_one::IntPlusOne);
store.register_early_pass(|| box formatting::Formatting);
store.register_early_pass(|| box misc_early::MiscEarlyLints);
store.register_early_pass(|| box redundant_closure_call::RedundantClosureCall);
store.register_late_pass(|| box redundant_closure_call::RedundantClosureCall);
store.register_early_pass(|| box returns::Return);
store.register_late_pass(|| box let_and_return::LetReturn);
store.register_early_pass(|| box collapsible_if::CollapsibleIf);
@ -1359,7 +1362,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&misc_early::DOUBLE_NEG),
LintId::of(&misc_early::DUPLICATE_UNDERSCORE_ARGUMENT),
LintId::of(&misc_early::MIXED_CASE_HEX_LITERALS),
LintId::of(&misc_early::REDUNDANT_CLOSURE_CALL),
LintId::of(&misc_early::REDUNDANT_PATTERN),
LintId::of(&misc_early::UNNEEDED_WILDCARD_PATTERN),
LintId::of(&misc_early::ZERO_PREFIXED_LITERAL),
@ -1393,6 +1395,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&ranges::RANGE_ZIP_WITH_LEN),
LintId::of(&ranges::REVERSED_EMPTY_RANGES),
LintId::of(&redundant_clone::REDUNDANT_CLONE),
LintId::of(&redundant_closure_call::REDUNDANT_CLOSURE_CALL),
LintId::of(&redundant_field_names::REDUNDANT_FIELD_NAMES),
LintId::of(&redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES),
LintId::of(&reference::DEREF_ADDROF),
@ -1593,7 +1596,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&methods::UNNECESSARY_FILTER_MAP),
LintId::of(&methods::USELESS_ASREF),
LintId::of(&misc::SHORT_CIRCUIT_STATEMENT),
LintId::of(&misc_early::REDUNDANT_CLOSURE_CALL),
LintId::of(&misc_early::UNNEEDED_WILDCARD_PATTERN),
LintId::of(&misc_early::ZERO_PREFIXED_LITERAL),
LintId::of(&needless_bool::BOOL_COMPARISON),
@ -1608,6 +1610,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&precedence::PRECEDENCE),
LintId::of(&ptr_offset_with_cast::PTR_OFFSET_WITH_CAST),
LintId::of(&ranges::RANGE_ZIP_WITH_LEN),
LintId::of(&redundant_closure_call::REDUNDANT_CLOSURE_CALL),
LintId::of(&reference::DEREF_ADDROF),
LintId::of(&reference::REF_IN_DEREF),
LintId::of(&repeat_once::REPEAT_ONCE),

108
clippy_lints/src/misc_early.rs
View file

@ -1,13 +1,9 @@
use crate::utils::{
constants, snippet_opt, snippet_with_applicability, span_lint, span_lint_and_help, span_lint_and_sugg,
span_lint_and_then,
};
use if_chain::if_chain;
use crate::utils::{constants, snippet_opt, span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then};
use rustc_ast::ast::{
BindingMode, Block, Expr, ExprKind, GenericParamKind, Generics, Lit, LitFloatType, LitIntType, LitKind, Mutability,
NodeId, Pat, PatKind, StmtKind, UnOp,
BindingMode, Expr, ExprKind, GenericParamKind, Generics, Lit, LitFloatType, LitIntType, LitKind, Mutability,
NodeId, Pat, PatKind, UnOp,
};
use rustc_ast::visit::{walk_expr, FnKind, Visitor};
use rustc_ast::visit::FnKind;
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::Applicability;
use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
@ -70,28 +66,6 @@ declare_clippy_lint! {
"function arguments having names which only differ by an underscore"
}
declare_clippy_lint! {
/// **What it does:** Detects closures called in the same expression where they
/// are defined.
///
/// **Why is this bad?** It is unnecessarily adding to the expression's
/// complexity.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// // Bad
/// let a = (|| 42)()
///
/// // Good
/// let a = 42
/// ```
pub REDUNDANT_CLOSURE_CALL,
complexity,
"throwaway closures called in the expression they are defined"
}
declare_clippy_lint! {
/// **What it does:** Detects expressions of the form `--x`.
///
@ -278,7 +252,6 @@ declare_clippy_lint! {
declare_lint_pass!(MiscEarlyLints => [
UNNEEDED_FIELD_PATTERN,
DUPLICATE_UNDERSCORE_ARGUMENT,
REDUNDANT_CLOSURE_CALL,
DOUBLE_NEG,
MIXED_CASE_HEX_LITERALS,
UNSEPARATED_LITERAL_SUFFIX,
@ -288,30 +261,6 @@ declare_lint_pass!(MiscEarlyLints => [
UNNEEDED_WILDCARD_PATTERN,
]);
// Used to find `return` statements or equivalents e.g., `?`
struct ReturnVisitor {
found_return: bool,
}
impl ReturnVisitor {
#[must_use]
fn new() -> Self {
Self { found_return: false }
}
}
impl<'ast> Visitor<'ast> for ReturnVisitor {
fn visit_expr(&mut self, ex: &'ast Expr) {
if let ExprKind::Ret(_) = ex.kind {
self.found_return = true;
} else if let ExprKind::Try(_) = ex.kind {
self.found_return = true;
}
walk_expr(self, ex)
}
}
impl EarlyLintPass for MiscEarlyLints {
fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
for param in &gen.params {
@ -453,30 +402,6 @@ impl EarlyLintPass for MiscEarlyLints {
return;
}
match expr.kind {
ExprKind::Call(ref paren, _) => {
if let ExprKind::Paren(ref closure) = paren.kind {
if let ExprKind::Closure(_, _, _, ref decl, ref block, _) = closure.kind {
let mut visitor = ReturnVisitor::new();
visitor.visit_expr(block);
if !visitor.found_return {
span_lint_and_then(
cx,
REDUNDANT_CLOSURE_CALL,
expr.span,
"Try not to call a closure in the expression where it is declared.",
|diag| {
if decl.inputs.is_empty() {
let mut app = Applicability::MachineApplicable;
let hint =
snippet_with_applicability(cx, block.span, "..", &mut app).into_owned();
diag.span_suggestion(expr.span, "Try doing something like: ", hint, app);
}
},
);
}
}
}
},
ExprKind::Unary(UnOp::Neg, ref inner) => {
if let ExprKind::Unary(UnOp::Neg, _) = inner.kind {
span_lint(
@ -491,31 +416,6 @@ impl EarlyLintPass for MiscEarlyLints {
_ => (),
}
}
fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
for w in block.stmts.windows(2) {
if_chain! {
if let StmtKind::Local(ref local) = w[0].kind;
if let Option::Some(ref t) = local.init;
if let ExprKind::Closure(..) = t.kind;
if let PatKind::Ident(_, ident, _) = local.pat.kind;
if let StmtKind::Semi(ref second) = w[1].kind;
if let ExprKind::Assign(_, ref call, _) = second.kind;
if let ExprKind::Call(ref closure, _) = call.kind;
if let ExprKind::Path(_, ref path) = closure.kind;
then {
if ident == path.segments[0].ident {
span_lint(
cx,
REDUNDANT_CLOSURE_CALL,
second.span,
"Closure called just once immediately after it was declared",
);
}
}
}
}
}
}
impl MiscEarlyLints {

151
clippy_lints/src/redundant_closure_call.rs Normal file
View file

@ -0,0 +1,151 @@
use crate::utils::{snippet_with_applicability, span_lint, span_lint_and_then};
use if_chain::if_chain;
use rustc_ast::ast;
use rustc_ast::visit as ast_visit;
use rustc_ast::visit::Visitor as AstVisitor;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::intravisit as hir_visit;
use rustc_hir::intravisit::Visitor as HirVisitor;
use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
use rustc_middle::hir::map::Map;
use rustc_middle::lint::in_external_macro;
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **What it does:** Detects closures called in the same expression where they
/// are defined.
///
/// **Why is this bad?** It is unnecessarily adding to the expression's
/// complexity.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// // Bad
/// let a = (|| 42)()
///
/// // Good
/// let a = 42
/// ```
pub REDUNDANT_CLOSURE_CALL,
complexity,
"throwaway closures called in the expression they are defined"
}
declare_lint_pass!(RedundantClosureCall => [REDUNDANT_CLOSURE_CALL]);
// Used to find `return` statements or equivalents e.g., `?`
struct ReturnVisitor {
found_return: bool,
}
impl ReturnVisitor {
#[must_use]
fn new() -> Self {
Self { found_return: false }
}
}
impl<'ast> ast_visit::Visitor<'ast> for ReturnVisitor {
fn visit_expr(&mut self, ex: &'ast ast::Expr) {
if let ast::ExprKind::Ret(_) = ex.kind {
self.found_return = true;
} else if let ast::ExprKind::Try(_) = ex.kind {
self.found_return = true;
}
ast_visit::walk_expr(self, ex)
}
}
impl EarlyLintPass for RedundantClosureCall {
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
if in_external_macro(cx.sess(), expr.span) {
return;
}
if_chain! {
if let ast::ExprKind::Call(ref paren, _) = expr.kind;
if let ast::ExprKind::Paren(ref closure) = paren.kind;
if let ast::ExprKind::Closure(_, _, _, ref decl, ref block, _) = closure.kind;
then {
let mut visitor = ReturnVisitor::new();
visitor.visit_expr(block);
if !visitor.found_return {
span_lint_and_then(
cx,
REDUNDANT_CLOSURE_CALL,
expr.span,
"try not to call a closure in the expression where it is declared.",
|diag| {
if decl.inputs.is_empty() {
let mut app = Applicability::MachineApplicable;
let hint =
snippet_with_applicability(cx, block.span, "..", &mut app).into_owned();
diag.span_suggestion(expr.span, "try doing something like", hint, app);
}
},
);
}
}
}
}
}
impl<'tcx> LateLintPass<'tcx> for RedundantClosureCall {
fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx hir::Block<'_>) {
fn count_closure_usage<'tcx>(block: &'tcx hir::Block<'_>, path: &'tcx hir::Path<'tcx>) -> usize {
struct ClosureUsageCount<'tcx> {
path: &'tcx hir::Path<'tcx>,
count: usize,
};
impl<'tcx> hir_visit::Visitor<'tcx> for ClosureUsageCount<'tcx> {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
if_chain! {
if let hir::ExprKind::Call(ref closure, _) = expr.kind;
if let hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) = closure.kind;
if self.path.segments[0].ident == path.segments[0].ident
&& self.path.res == path.res;
then {
self.count += 1;
}
}
hir_visit::walk_expr(self, expr);
}
fn nested_visit_map(&mut self) -> hir_visit::NestedVisitorMap<Self::Map> {
hir_visit::NestedVisitorMap::None
}
};
let mut closure_usage_count = ClosureUsageCount { path, count: 0 };
closure_usage_count.visit_block(block);
closure_usage_count.count
}
for w in block.stmts.windows(2) {
if_chain! {
if let hir::StmtKind::Local(ref local) = w[0].kind;
if let Option::Some(ref t) = local.init;
if let hir::ExprKind::Closure(..) = t.kind;
if let hir::PatKind::Binding(_, _, ident, _) = local.pat.kind;
if let hir::StmtKind::Semi(ref second) = w[1].kind;
if let hir::ExprKind::Assign(_, ref call, _) = second.kind;
if let hir::ExprKind::Call(ref closure, _) = call.kind;
if let hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) = closure.kind;
if ident == path.segments[0].ident;
if count_closure_usage(block, path) == 1;
then {
span_lint(
cx,
REDUNDANT_CLOSURE_CALL,
second.span,
"closure called just once immediately after it was declared",
);
}
}
}
}
}

2
src/lintlist/mod.rs
View file

@ -1835,7 +1835,7 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
group: "complexity",
desc: "throwaway closures called in the expression they are defined",
deprecation: None,
module: "misc_early",
module: "redundant_closure_call",
},
Lint {
name: "redundant_closure_for_method_calls",

28
tests/ui/redundant_closure_call.stderr
View file

@ -1,28 +0,0 @@
error: Closure called just once immediately after it was declared
--> $DIR/redundant_closure_call.rs:12:5
|
LL | i = 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
|
LL | let mut k = (|m| m + 1)(i);
| ^^^^^^^^^^^^^^
error: Try not to call a closure in the expression where it is declared.
--> $DIR/redundant_closure_call.rs:9:9
|
LL | k = (|a, b| a * b)(1, 5);
| ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors

12
tests/ui/redundant_closure_call.rs → tests/ui/redundant_closure_call_early.rs
View file

@ -4,18 +4,14 @@
fn main() {
let mut i = 1;
// lint here
let mut k = (|m| m + 1)(i);
// lint here
k = (|a, b| a * b)(1, 5);
let closure = || 32;
i = closure();
let closure = |i| i + 1;
i = closure(3);
i = closure(4);
// don't lint these
#[allow(clippy::needless_return)]
(|| return 2)();
(|| -> Option<i32> { None? })();

16
tests/ui/redundant_closure_call_early.stderr Normal file
View file

@ -0,0 +1,16 @@
error: try not to call a closure in the expression where it is declared.
--> $DIR/redundant_closure_call_early.rs:9:17
|
LL | let mut k = (|m| m + 1)(i);
| ^^^^^^^^^^^^^^
|
= note: `-D clippy::redundant-closure-call` implied by `-D warnings`
error: try not to call a closure in the expression where it is declared.
--> $DIR/redundant_closure_call_early.rs:12:9
|
LL | k = (|a, b| a * b)(1, 5);
| ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 2 previous errors

4
tests/ui/redundant_closure_call_fixable.stderr
View file

@ -1,8 +1,8 @@
error: Try not to call a closure in the expression where it is declared.
error: try not to call a closure in the expression where it is declared.
--> $DIR/redundant_closure_call_fixable.rs:7:13
|
LL | let a = (|| 42)();
| ^^^^^^^^^ help: Try doing something like: : `42`
| ^^^^^^^^^ help: try doing something like: `42`
|
= note: `-D clippy::redundant-closure-call` implied by `-D warnings`

27
tests/ui/redundant_closure_call_late.rs Normal file
View file

@ -0,0 +1,27 @@
// non rustfixable, see redundant_closure_call_fixable.rs
#![warn(clippy::redundant_closure_call)]
fn main() {
let mut i = 1;
// 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();
// shadowed closures are supported, lint here
let shadowed_closure = || 1;
i = shadowed_closure();
let shadowed_closure = || 2;
i = shadowed_closure();
// don't lint here
let shadowed_closure = || 2;
i = shadowed_closure();
i = shadowed_closure();
}

22
tests/ui/redundant_closure_call_late.stderr Normal file
View file

@ -0,0 +1,22 @@
error: closure called just once immediately after it was declared
--> $DIR/redundant_closure_call_late.rs:15:5
|
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_late.rs:19:5
|
LL | i = shadowed_closure();
| ^^^^^^^^^^^^^^^^^^^^^^
error: closure called just once immediately after it was declared
--> $DIR/redundant_closure_call_late.rs:21:5
|
LL | i = shadowed_closure();
| ^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 3 previous errors