diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs index 3db6b302790..6041f80753b 100644 --- a/compiler/rustc_lint/src/unused.rs +++ b/compiler/rustc_lint/src/unused.rs @@ -666,6 +666,24 @@ fn is_expr_delims_necessary( if !followed_by_block { return false; } + + // Check if we need parens for `match &( Struct { feild: }) {}`. + { + let mut innermost = inner; + loop { + innermost = match &innermost.kind { + ExprKind::AddrOf(_, _, expr) => expr, + _ => { + if parser::contains_exterior_struct_lit(&innermost) { + return true; + } else { + break; + } + } + } + } + } + let mut innermost = inner; loop { innermost = match &innermost.kind { diff --git a/tests/ui/lint/lint-struct-necessary.rs b/tests/ui/lint/lint-struct-necessary.rs new file mode 100644 index 00000000000..8bc3c12054a --- /dev/null +++ b/tests/ui/lint/lint-struct-necessary.rs @@ -0,0 +1,31 @@ +#![allow(dead_code)] +#![deny(unused_parens)] + +enum State { + Waiting { start_at: u64 } +} +struct Foo {} + +fn main() { + let e = &mut State::Waiting { start_at: 0u64 }; + match (&mut State::Waiting { start_at: 0u64 }) { + _ => {} + } + + match (e) { + //~^ ERROR unnecessary parentheses around `match` scrutinee expression + _ => {} + } + + match &(State::Waiting { start_at: 0u64 }) { + _ => {} + } + + match (State::Waiting { start_at: 0u64 }) { + _ => {} + } + + match (&&Foo {}) { + _ => {} + } +} diff --git a/tests/ui/lint/lint-struct-necessary.stderr b/tests/ui/lint/lint-struct-necessary.stderr new file mode 100644 index 00000000000..eb65a9e98c6 --- /dev/null +++ b/tests/ui/lint/lint-struct-necessary.stderr @@ -0,0 +1,19 @@ +error: unnecessary parentheses around `match` scrutinee expression + --> $DIR/lint-struct-necessary.rs:15:11 + | +LL | match (e) { + | ^ ^ + | +note: the lint level is defined here + --> $DIR/lint-struct-necessary.rs:2:9 + | +LL | #![deny(unused_parens)] + | ^^^^^^^^^^^^^ +help: remove these parentheses + | +LL - match (e) { +LL + match e { + | + +error: aborting due to previous error +