From 2fe73cea5ef8e381e47161468167c90ed3fb724a Mon Sep 17 00:00:00 2001
From: yukang <moorekang@gmail.com>
Date: Wed, 14 Feb 2024 15:15:22 +0800
Subject: [PATCH] Fix false positive with if let and ranges
---
compiler/rustc_lint/src/unused.rs | 16 ++++++++++++----
tests/ui/lint/issue-121070-let-range.rs | 16 ++++++++++++++++
2 files changed, 28 insertions(+), 4 deletions(-)
create mode 100644 tests/ui/lint/issue-121070-let-range.rs
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
index 9f670893b27..35ee0c53046 100644
--- a/compiler/rustc_lint/src/unused.rs
+++ b/compiler/rustc_lint/src/unused.rs
@@ -651,9 +651,11 @@ trait UnusedDelimLint {
fn is_expr_delims_necessary(
inner: &ast::Expr,
+ ctx: UnusedDelimsCtx,
followed_by_block: bool,
- followed_by_else: bool,
) -> bool {
+ let followed_by_else = ctx == UnusedDelimsCtx::AssignedValueLetElse;
+
if followed_by_else {
match inner.kind {
ast::ExprKind::Binary(op, ..) if op.node.is_lazy() => return true,
@@ -662,6 +664,13 @@ trait UnusedDelimLint {
}
}
+ // Check it's range in LetScrutineeExpr
+ if let ast::ExprKind::Range(..) = inner.kind
+ && matches!(ctx, UnusedDelimsCtx::LetScrutineeExpr)
+ {
+ return true;
+ }
+
// Check if LHS needs parens to prevent false-positives in cases like `fn x() -> u8 { ({ 0 } + 1) }`.
{
let mut innermost = inner;
@@ -1007,8 +1016,7 @@ impl UnusedDelimLint for UnusedParens {
) {
match value.kind {
ast::ExprKind::Paren(ref inner) => {
- let followed_by_else = ctx == UnusedDelimsCtx::AssignedValueLetElse;
- if !Self::is_expr_delims_necessary(inner, followed_by_block, followed_by_else)
+ if !Self::is_expr_delims_necessary(inner, ctx, followed_by_block)
&& value.attrs.is_empty()
&& !value.span.from_expansion()
&& (ctx != UnusedDelimsCtx::LetScrutineeExpr
@@ -1334,7 +1342,7 @@ impl UnusedDelimLint for UnusedBraces {
// FIXME(const_generics): handle paths when #67075 is fixed.
if let [stmt] = inner.stmts.as_slice() {
if let ast::StmtKind::Expr(ref expr) = stmt.kind {
- if !Self::is_expr_delims_necessary(expr, followed_by_block, false)
+ if !Self::is_expr_delims_necessary(expr, ctx, followed_by_block)
&& (ctx != UnusedDelimsCtx::AnonConst
|| (matches!(expr.kind, ast::ExprKind::Lit(_))
&& !expr.span.from_expansion()))
diff --git a/tests/ui/lint/issue-121070-let-range.rs b/tests/ui/lint/issue-121070-let-range.rs
new file mode 100644
index 00000000000..84598dcd258
--- /dev/null
+++ b/tests/ui/lint/issue-121070-let-range.rs
@@ -0,0 +1,16 @@
+// check-pass
+
+#![feature(let_chains)]
+#![allow(irrefutable_let_patterns)]
+fn main() {
+ let _a = 0..1;
+
+ if let x = (0..1) {
+ eprintln!("x: {:?}", x);
+ }
+ if let x = (0..1) &&
+ let _y = (0..2)
+ {
+ eprintln!("x: {:?}", x);
+ }
+}