diff --git a/clippy_lints/src/let_with_type_underscore.rs b/clippy_lints/src/let_with_type_underscore.rs index 2f10e3d25..4e9d77ea1 100644 --- a/clippy_lints/src/let_with_type_underscore.rs +++ b/clippy_lints/src/let_with_type_underscore.rs @@ -1,4 +1,5 @@ use clippy_utils::diagnostics::span_lint_and_help; +use clippy_utils::source::snippet; use rustc_hir::{Local, TyKind}; use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::lint::in_external_macro; @@ -25,14 +26,21 @@ declare_clippy_lint! { declare_lint_pass!(UnderscoreTyped => [LET_WITH_TYPE_UNDERSCORE]); impl LateLintPass<'_> for UnderscoreTyped { - fn check_local<'tcx>(&mut self, cx: &LateContext<'tcx>, local: &'tcx Local<'tcx>) { + fn check_local(&mut self, cx: &LateContext<'_>, local: &Local<'_>) { if_chain! { if !in_external_macro(cx.tcx.sess, local.span); if let Some(ty) = local.ty; // Ensure that it has a type defined if let TyKind::Infer = &ty.kind; // that type is '_' if local.span.ctxt() == ty.span.ctxt(); then { - span_lint_and_help(cx, + // NOTE: Using `is_from_proc_macro` on `init` will require that it's initialized, + // this doesn't. Alternatively, `WithSearchPat` can be implemented for `Ty` + if snippet(cx, ty.span, "_").trim() != "_" { + return; + } + + span_lint_and_help( + cx, LET_WITH_TYPE_UNDERSCORE, local.span, "variable declared with type underscore", diff --git a/tests/ui/let_with_type_underscore.rs b/tests/ui/let_with_type_underscore.rs index 7c1835e8c..ae1a480bc 100644 --- a/tests/ui/let_with_type_underscore.rs +++ b/tests/ui/let_with_type_underscore.rs @@ -1,19 +1,42 @@ +//@aux-build: proc_macros.rs #![allow(unused)] #![warn(clippy::let_with_type_underscore)] -#![allow(clippy::let_unit_value)] +#![allow(clippy::let_unit_value, clippy::needless_late_init)] + +extern crate proc_macros; fn func() -> &'static str { "" } +#[rustfmt::skip] fn main() { // Will lint let x: _ = 1; let _: _ = 2; let x: _ = func(); + let x: _; + x = (); let x = 1; // Will not lint, Rust infers this to an integer before Clippy let x = func(); let x: Vec<_> = Vec::::new(); let x: [_; 1] = [1]; + let x : _ = 1; + + // Do not lint from procedural macros + proc_macros::with_span! { + span + let x: _ = (); + // Late initialization + let x: _; + x = (); + // Ensure weird formatting will not break it (hopefully) + let x : _ = 1; + let x +: _ = 1; + let x : + _; + x = (); + }; } diff --git a/tests/ui/let_with_type_underscore.stderr b/tests/ui/let_with_type_underscore.stderr index 16bf83c70..a749552c7 100644 --- a/tests/ui/let_with_type_underscore.stderr +++ b/tests/ui/let_with_type_underscore.stderr @@ -1,39 +1,63 @@ error: variable declared with type underscore - --> $DIR/let_with_type_underscore.rs:11:5 + --> $DIR/let_with_type_underscore.rs:15:5 | LL | let x: _ = 1; | ^^^^^^^^^^^^^ | help: remove the explicit type `_` declaration - --> $DIR/let_with_type_underscore.rs:11:10 + --> $DIR/let_with_type_underscore.rs:15:10 | LL | let x: _ = 1; | ^^^ = note: `-D clippy::let-with-type-underscore` implied by `-D warnings` error: variable declared with type underscore - --> $DIR/let_with_type_underscore.rs:12:5 + --> $DIR/let_with_type_underscore.rs:16:5 | LL | let _: _ = 2; | ^^^^^^^^^^^^^ | help: remove the explicit type `_` declaration - --> $DIR/let_with_type_underscore.rs:12:10 + --> $DIR/let_with_type_underscore.rs:16:10 | LL | let _: _ = 2; | ^^^ error: variable declared with type underscore - --> $DIR/let_with_type_underscore.rs:13:5 + --> $DIR/let_with_type_underscore.rs:17:5 | LL | let x: _ = func(); | ^^^^^^^^^^^^^^^^^^ | help: remove the explicit type `_` declaration - --> $DIR/let_with_type_underscore.rs:13:10 + --> $DIR/let_with_type_underscore.rs:17:10 | LL | let x: _ = func(); | ^^^ -error: aborting due to 3 previous errors +error: variable declared with type underscore + --> $DIR/let_with_type_underscore.rs:18:5 + | +LL | let x: _; + | ^^^^^^^^^ + | +help: remove the explicit type `_` declaration + --> $DIR/let_with_type_underscore.rs:18:10 + | +LL | let x: _; + | ^^^ + +error: variable declared with type underscore + --> $DIR/let_with_type_underscore.rs:25:5 + | +LL | let x : _ = 1; + | ^^^^^^^^^^^^^^ + | +help: remove the explicit type `_` declaration + --> $DIR/let_with_type_underscore.rs:25:10 + | +LL | let x : _ = 1; + | ^^^^ + +error: aborting due to 5 previous errors