diff --git a/clippy_lints/src/operators/identity_op.rs b/clippy_lints/src/operators/identity_op.rs index e1fd09549a4b..7e515e83cc9d 100644 --- a/clippy_lints/src/operators/identity_op.rs +++ b/clippy_lints/src/operators/identity_op.rs @@ -1,12 +1,13 @@ use clippy_utils::consts::{ConstEvalCtxt, Constant, FullInt}; use clippy_utils::diagnostics::span_lint_and_sugg; use clippy_utils::source::snippet_with_applicability; -use clippy_utils::{clip, peel_hir_expr_refs, unsext}; +use clippy_utils::{ExprUseNode, clip, expr_use_ctxt, peel_hir_expr_refs, unsext}; use rustc_errors::Applicability; -use rustc_hir::{BinOpKind, Expr, ExprKind, Node}; +use rustc_hir::def::{DefKind, Res}; +use rustc_hir::{BinOpKind, Expr, ExprKind, Node, Path, QPath}; use rustc_lint::LateContext; use rustc_middle::ty; -use rustc_span::Span; +use rustc_span::{Span, kw}; use super::IDENTITY_OP; @@ -17,7 +18,7 @@ pub(crate) fn check<'tcx>( left: &'tcx Expr<'_>, right: &'tcx Expr<'_>, ) { - if !is_allowed(cx, op, left, right) { + if !is_allowed(cx, expr, op, left, right) { return; } @@ -165,7 +166,22 @@ fn needs_parenthesis(cx: &LateContext<'_>, binary: &Expr<'_>, child: &Expr<'_>) Parens::Needed } -fn is_allowed(cx: &LateContext<'_>, cmp: BinOpKind, left: &Expr<'_>, right: &Expr<'_>) -> bool { +fn is_allowed<'tcx>( + cx: &LateContext<'tcx>, + expr: &'tcx Expr<'tcx>, + cmp: BinOpKind, + left: &Expr<'tcx>, + right: &Expr<'tcx>, +) -> bool { + // Exclude case where the left or right side is associated function call returns a type which is + // `Self` that is not given explicitly, and the expression is not a let binding's init + // expression and the let binding has a type annotation, or a function's return value. + if (is_assoc_fn_without_type_instance(cx, left) || is_assoc_fn_without_type_instance(cx, right)) + && !is_expr_used_with_type_annotation(cx, expr) + { + return false; + } + // This lint applies to integers and their references cx.typeck_results().expr_ty(left).peel_refs().is_integral() && cx.typeck_results().expr_ty(right).peel_refs().is_integral() @@ -234,3 +250,47 @@ fn span_ineffective_operation( applicability, ); } + +fn is_expr_used_with_type_annotation<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool { + match expr_use_ctxt(cx, expr).use_node(cx) { + ExprUseNode::LetStmt(letstmt) => letstmt.ty.is_some(), + ExprUseNode::Return(_) => true, + _ => false, + } +} + +/// Check if the expression is an associated function without a type instance. +/// Example: +/// ``` +/// trait Def { +/// fn def() -> Self; +/// } +/// impl Def for usize { +/// fn def() -> Self { +/// 0 +/// } +/// } +/// fn test() { +/// let _ = 0usize + &Default::default(); +/// let _ = 0usize + &Def::def(); +/// } +/// ``` +fn is_assoc_fn_without_type_instance<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> bool { + if let ExprKind::Call(func, _) = peel_hir_expr_refs(expr).0.kind + && let ExprKind::Path(QPath::Resolved( + // If it's not None, don't need to go further. + None, + Path { + res: Res::Def(DefKind::AssocFn, def_id), + .. + }, + )) = func.kind + && let output_ty = cx.tcx.fn_sig(def_id).instantiate_identity().skip_binder().output() + && let ty::Param(ty::ParamTy { + name: kw::SelfUpper, .. + }) = output_ty.kind() + { + return true; + } + false +} diff --git a/tests/ui/identity_op.fixed b/tests/ui/identity_op.fixed index a1b556029987..4e14e1a5e33f 100644 --- a/tests/ui/identity_op.fixed +++ b/tests/ui/identity_op.fixed @@ -312,3 +312,49 @@ fn issue_13470() { let _: u64 = 1u64 + ((x as i32 + y as i32) as u64); //~^ identity_op } + +fn issue_14932() { + let _ = 0usize + &Default::default(); // no error + + 0usize + &Default::default(); // no error + + ::default(); + //~^ identity_op + + let _ = usize::default(); + //~^ identity_op + + let _n: usize = Default::default(); + //~^ identity_op +} + +// Expr's type can be inferred by the function's return type +fn issue_14932_2() -> usize { + Default::default() + //~^ identity_op +} + +trait Def { + fn def() -> Self; +} + +impl Def for usize { + fn def() -> Self { + 0 + } +} + +fn issue_14932_3() { + let _ = 0usize + &Def::def(); // no error + + 0usize + &Def::def(); // no error + + ::def(); + //~^ identity_op + + let _ = usize::def(); + //~^ identity_op + + let _n: usize = Def::def(); + //~^ identity_op +} diff --git a/tests/ui/identity_op.rs b/tests/ui/identity_op.rs index f603e1078e4e..ebbef5723ffb 100644 --- a/tests/ui/identity_op.rs +++ b/tests/ui/identity_op.rs @@ -312,3 +312,49 @@ fn issue_13470() { let _: u64 = 1u64 + ((x as i32 + y as i32) as u64 + 0u64); //~^ identity_op } + +fn issue_14932() { + let _ = 0usize + &Default::default(); // no error + + 0usize + &Default::default(); // no error + + 0usize + &::default(); + //~^ identity_op + + let _ = 0usize + &usize::default(); + //~^ identity_op + + let _n: usize = 0usize + &Default::default(); + //~^ identity_op +} + +// Expr's type can be inferred by the function's return type +fn issue_14932_2() -> usize { + 0usize + &Default::default() + //~^ identity_op +} + +trait Def { + fn def() -> Self; +} + +impl Def for usize { + fn def() -> Self { + 0 + } +} + +fn issue_14932_3() { + let _ = 0usize + &Def::def(); // no error + + 0usize + &Def::def(); // no error + + 0usize + &::def(); + //~^ identity_op + + let _ = 0usize + &usize::def(); + //~^ identity_op + + let _n: usize = 0usize + &Def::def(); + //~^ identity_op +} diff --git a/tests/ui/identity_op.stderr b/tests/ui/identity_op.stderr index 8f9c2b603c49..24fa5db08ce5 100644 --- a/tests/ui/identity_op.stderr +++ b/tests/ui/identity_op.stderr @@ -379,5 +379,47 @@ error: this operation has no effect LL | let _: u64 = 1u64 + ((x as i32 + y as i32) as u64 + 0u64); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `((x as i32 + y as i32) as u64)` -error: aborting due to 63 previous errors +error: this operation has no effect + --> tests/ui/identity_op.rs:321:5 + | +LL | 0usize + &::default(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `::default()` + +error: this operation has no effect + --> tests/ui/identity_op.rs:324:13 + | +LL | let _ = 0usize + &usize::default(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `usize::default()` + +error: this operation has no effect + --> tests/ui/identity_op.rs:327:21 + | +LL | let _n: usize = 0usize + &Default::default(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `Default::default()` + +error: this operation has no effect + --> tests/ui/identity_op.rs:333:5 + | +LL | 0usize + &Default::default() + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `Default::default()` + +error: this operation has no effect + --> tests/ui/identity_op.rs:352:5 + | +LL | 0usize + &::def(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `::def()` + +error: this operation has no effect + --> tests/ui/identity_op.rs:355:13 + | +LL | let _ = 0usize + &usize::def(); + | ^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `usize::def()` + +error: this operation has no effect + --> tests/ui/identity_op.rs:358:21 + | +LL | let _n: usize = 0usize + &Def::def(); + | ^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `Def::def()` + +error: aborting due to 70 previous errors