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Better handle method/function calls

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Serial 2022-08-05 13:49:43 -04:00
parent 2666c38acb
commit 0efafa4a6e
5 changed files with 108 additions and 50 deletions
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2
clippy_lints/src/lib.register_suspicious.rs
View file

@ -32,6 +32,6 @@ store.register_group(true, "clippy::suspicious", Some("clippy_suspicious"), vec!
LintId::of(suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL),
LintId::of(suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL),
LintId::of(swap_ptr_to_ref::SWAP_PTR_TO_REF),
LintId::of(write::POSITIONAL_NAMED_FORMAT_PARAMETERS),
LintId::of(unused_peekable::UNUSED_PEEKABLE),
LintId::of(write::POSITIONAL_NAMED_FORMAT_PARAMETERS),
])

2
clippy_lints/src/lib.rs
View file

@ -936,7 +936,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| Box::new(manual_instant_elapsed::ManualInstantElapsed));
store.register_late_pass(|| Box::new(partialeq_to_none::PartialeqToNone));
store.register_late_pass(|| Box::new(manual_empty_string_creations::ManualEmptyStringCreations));
store.register_late_pass(|| Box::new(unused_peekable::UnusedPeekable::default()));
store.register_late_pass(|| Box::new(unused_peekable::UnusedPeekable));
// add lints here, do not remove this comment, it's used in `new_lint`
}

109
clippy_lints/src/unused_peekable.rs
View file

@ -1,13 +1,13 @@
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::ty::{match_type, peel_mid_ty_refs_is_mutable};
use clippy_utils::{fn_def_id, path_to_local_id, paths, peel_ref_operators};
use clippy_utils::{fn_def_id, is_trait_method, path_to_local_id, paths, peel_ref_operators};
use rustc_ast::Mutability;
use rustc_hir::intravisit::{walk_expr, Visitor};
use rustc_hir::lang_items::LangItem;
use rustc_hir::{Block, Expr, ExprKind, HirId, Local, Node, PatKind, PathSegment, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::Ty;
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
declare_clippy_lint! {
/// ### What it does
@ -42,12 +42,7 @@ declare_clippy_lint! {
"creating a peekable iterator without using any of its methods"
}
#[derive(Default)]
pub struct UnusedPeekable {
visited: Vec<HirId>,
}
impl_lint_pass!(UnusedPeekable => [UNUSED_PEEKABLE]);
declare_lint_pass!(UnusedPeekable => [UNUSED_PEEKABLE]);
impl<'tcx> LateLintPass<'tcx> for UnusedPeekable {
fn check_block(&mut self, cx: &LateContext<'tcx>, block: &Block<'tcx>) {
@ -62,15 +57,14 @@ impl<'tcx> LateLintPass<'tcx> for UnusedPeekable {
for (idx, stmt) in block.stmts.iter().enumerate() {
if !stmt.span.from_expansion()
&& let StmtKind::Local(local) = stmt.kind
&& !self.visited.contains(&local.pat.hir_id)
&& let PatKind::Binding(_, _, ident, _) = local.pat.kind
&& let PatKind::Binding(_, binding, ident, _) = local.pat.kind
&& let Some(init) = local.init
&& !init.span.from_expansion()
&& let Some(ty) = cx.typeck_results().expr_ty_opt(init)
&& let (ty, _, Mutability::Mut) = peel_mid_ty_refs_is_mutable(ty)
&& match_type(cx, ty, &paths::PEEKABLE)
{
let mut vis = PeekableVisitor::new(cx, local.pat.hir_id);
let mut vis = PeekableVisitor::new(cx, binding);
if idx + 1 == block.stmts.len() && block.expr.is_none() {
return;
@ -117,6 +111,10 @@ impl<'a, 'tcx> PeekableVisitor<'a, 'tcx> {
impl<'tcx> Visitor<'_> for PeekableVisitor<'_, 'tcx> {
fn visit_expr(&mut self, ex: &'_ Expr<'_>) {
if self.found_peek_call {
return;
}
if path_to_local_id(ex, self.expected_hir_id) {
for (_, node) in self.cx.tcx.hir().parent_iter(ex.hir_id) {
match node {
@ -138,50 +136,58 @@ impl<'tcx> Visitor<'_> for PeekableVisitor<'_, 'tcx> {
return;
}
for arg in args.iter().map(|arg| peel_ref_operators(self.cx, arg)) {
if let ExprKind::Path(_) = arg.kind
&& let Some(ty) = self
.cx
.typeck_results()
.expr_ty_opt(arg)
.map(Ty::peel_refs)
&& match_type(self.cx, ty, &paths::PEEKABLE)
{
self.found_peek_call = true;
return;
}
}
},
// Peekable::peek()
ExprKind::MethodCall(PathSegment { ident: method_name, .. }, [arg, ..], _) => {
let arg = peel_ref_operators(self.cx, arg);
let method_name = method_name.name.as_str();
if (method_name == "peek"
|| method_name == "peek_mut"
|| method_name == "next_if"
|| method_name == "next_if_eq")
&& let ExprKind::Path(_) = arg.kind
&& let Some(ty) = self.cx.typeck_results().expr_ty_opt(arg).map(Ty::peel_refs)
&& match_type(self.cx, ty, &paths::PEEKABLE)
{
if args.iter().any(|arg| {
matches!(arg.kind, ExprKind::Path(_)) && arg_is_mut_peekable(self.cx, arg)
}) {
self.found_peek_call = true;
return;
}
},
// Don't bother if moved into a struct
ExprKind::Struct(..) => {
// Catch anything taking a Peekable mutably
ExprKind::MethodCall(
PathSegment {
ident: method_name_ident,
..
},
[self_arg, remaining_args @ ..],
_,
) => {
let method_name = method_name_ident.name.as_str();
// `Peekable` methods
if matches!(method_name, "peek" | "peek_mut" | "next_if" | "next_if_eq")
&& arg_is_mut_peekable(self.cx, self_arg)
{
self.found_peek_call = true;
return;
}
// foo.some_method() excluding Iterator methods
if remaining_args.iter().any(|arg| arg_is_mut_peekable(self.cx, arg))
&& !is_trait_method(self.cx, expr, sym::Iterator)
{
self.found_peek_call = true;
return;
}
// foo.by_ref(), keep checking for `peek`
if method_name == "by_ref" {
continue;
}
return;
},
ExprKind::AddrOf(_, Mutability::Mut, _) | ExprKind::Unary(..) | ExprKind::DropTemps(_) => {
},
ExprKind::AddrOf(_, Mutability::Not, _) => return,
_ => {
self.found_peek_call = true;
return;
},
_ => {},
}
},
Node::Local(Local { init: Some(init), .. }) => {
if let Some(ty) = self.cx.typeck_results().expr_ty_opt(init)
&& let (ty, _, Mutability::Mut) = peel_mid_ty_refs_is_mutable(ty)
&& match_type(self.cx, ty, &paths::PEEKABLE)
{
if arg_is_mut_peekable(self.cx, init) {
self.found_peek_call = true;
return;
}
@ -206,3 +212,14 @@ impl<'tcx> Visitor<'_> for PeekableVisitor<'_, 'tcx> {
walk_expr(self, ex);
}
}
fn arg_is_mut_peekable(cx: &LateContext<'_>, arg: &Expr<'_>) -> bool {
if let Some(ty) = cx.typeck_results().expr_ty_opt(arg)
&& let (ty, _, Mutability::Mut) = peel_mid_ty_refs_is_mutable(ty)
&& match_type(cx, ty, &paths::PEEKABLE)
{
true
} else {
false
}
}

25
tests/ui/unused_peekable.rs
View file

@ -32,6 +32,15 @@ fn invalid() {
let mut peekable_using_iterator_method = std::iter::empty::<u32>().peekable();
peekable_using_iterator_method.next();
// Passed by ref to another function
fn takes_ref(_peek: &Peekable<Empty<u32>>) {}
let passed_along_ref = std::iter::empty::<u32>().peekable();
takes_ref(&passed_along_ref);
// `by_ref` without `peek`
let mut by_ref_test = std::iter::empty::<u32>().peekable();
let _by_ref = by_ref_test.by_ref();
let mut peekable_in_for_loop = std::iter::empty::<u32>().peekable();
for x in peekable_in_for_loop {}
}
@ -43,6 +52,18 @@ fn valid() {
let passed_along = std::iter::empty::<u32>().peekable();
takes_peekable(passed_along);
// Passed to another method
struct PeekableConsumer;
impl PeekableConsumer {
fn consume(&self, _: Peekable<Empty<u32>>) {}
fn consume_mut_ref(&self, _: &mut Peekable<Empty<u32>>) {}
}
let peekable_consumer = PeekableConsumer;
let mut passed_along_to_method = std::iter::empty::<u32>().peekable();
peekable_consumer.consume_mut_ref(&mut passed_along_to_method);
peekable_consumer.consume(passed_along_to_method);
// `peek` called in another block
let mut peekable_in_block = std::iter::empty::<u32>().peekable();
{
@ -111,6 +132,10 @@ fn valid() {
let struct_test = std::iter::empty::<u32>().peekable();
PeekableWrapper { f: struct_test };
// `by_ref` before `peek`
let mut by_ref_test = std::iter::empty::<u32>().peekable();
let peeked_val = by_ref_test.by_ref().peek();
// `peek` called in another block as the last expression
let mut peekable_last_expr = std::iter::empty::<u32>().peekable();
{

20
tests/ui/unused_peekable.stderr
View file

@ -40,12 +40,28 @@ LL | let mut peekable_using_iterator_method = std::iter::empty::<u32>().peek
= help: consider removing the call to `peekable`
error: `peek` never called on `Peekable` iterator
--> $DIR/unused_peekable.rs:35:13
--> $DIR/unused_peekable.rs:37:9
|
LL | let passed_along_ref = std::iter::empty::<u32>().peekable();
| ^^^^^^^^^^^^^^^^
|
= help: consider removing the call to `peekable`
error: `peek` never called on `Peekable` iterator
--> $DIR/unused_peekable.rs:42:9
|
LL | let _by_ref = by_ref_test.by_ref();
| ^^^^^^^
|
= help: consider removing the call to `peekable`
error: `peek` never called on `Peekable` iterator
--> $DIR/unused_peekable.rs:44:13
|
LL | let mut peekable_in_for_loop = std::iter::empty::<u32>().peekable();
| ^^^^^^^^^^^^^^^^^^^^
|
= help: consider removing the call to `peekable`
error: aborting due to 6 previous errors
error: aborting due to 8 previous errors