Rollup merge of #128782 - RalfJung:raw-addr-of-parens, r=compiler-errors

unused_parens: do not lint against parens around &raw Requested by `@tmandry` in #127679: with `&raw` one somewhat regularly has to write code like `(&raw const (*myptr).field).method()`, so parentheses around the expression are often required. To avoid churn between adding and removing parentheses as method calls appear and disappear, the proposal was made to silence the lint for unnecessary parentheses around `&raw` expressions. This PR implements that.
rust-lang · Aug 7, 2024 · aba506b · aba506b
2 parents 04ab8e3 + c189796
commit aba506b
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Showing 4 changed files with 79 additions and 32 deletions.
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
@@ -675,6 +675,13 @@ trait UnusedDelimLint {
             return true;
         }
 
+        // Do not lint against parentheses around `&raw [const|mut] expr`.
+        // These parentheses will have to be added e.g. when calling a method on the result of this
+        // expression, and we want to avoid churn wrt adding and removing parentheses.
+        if matches!(inner.kind, ast::ExprKind::AddrOf(ast::BorrowKind::Raw, ..)) {
+            return true;
+        }
+
         // Check if LHS needs parens to prevent false-positives in cases like
         // `fn x() -> u8 { ({ 0 } + 1) }`.
         //

diff --git a/tests/ui/lint/lint-unnecessary-parens.fixed b/tests/ui/lint/lint-unnecessary-parens.fixed
@@ -1,6 +1,7 @@
 //@ run-rustfix
 
 #![deny(unused_parens)]
+#![feature(raw_ref_op)]
 #![allow(while_true)] // for rustfix
 
 #[derive(Eq, PartialEq)]
@@ -125,4 +126,11 @@ fn main() {
         // FIXME: false positive. This parenthesis is required.
         unit! {} - One //~ ERROR unnecessary parentheses around block return value
     };
+
+    // Do *not* lint around `&raw` (but do lint when `&` creates a reference).
+    let mut x = 0;
+    let _r = &x; //~ ERROR unnecessary parentheses
+    let _r = &mut x; //~ ERROR unnecessary parentheses
+    let _r = (&raw const x);
+    let _r = (&raw mut x);
 }
diff --git a/tests/ui/lint/lint-unnecessary-parens.rs b/tests/ui/lint/lint-unnecessary-parens.rs
@@ -1,6 +1,7 @@
 //@ run-rustfix
 
 #![deny(unused_parens)]
+#![feature(raw_ref_op)]
 #![allow(while_true)] // for rustfix
 
 #[derive(Eq, PartialEq)]
@@ -125,4 +126,11 @@ fn main() {
         // FIXME: false positive. This parenthesis is required.
         (unit! {} - One) //~ ERROR unnecessary parentheses around block return value
     };
+
+    // Do *not* lint around `&raw` (but do lint when `&` creates a reference).
+    let mut x = 0;
+    let _r = (&x); //~ ERROR unnecessary parentheses
+    let _r = (&mut x); //~ ERROR unnecessary parentheses
+    let _r = (&raw const x);
+    let _r = (&raw mut x);
 }
diff --git a/tests/ui/lint/lint-unnecessary-parens.stderr b/tests/ui/lint/lint-unnecessary-parens.stderr
@@ -1,5 +1,5 @@
 error: unnecessary parentheses around `return` value
-  --> $DIR/lint-unnecessary-parens.rs:13:12
+  --> $DIR/lint-unnecessary-parens.rs:14:12
    |
 LL |     return (1);
    |            ^ ^
@@ -16,7 +16,7 @@ LL +     return 1;
    |
 
 error: unnecessary parentheses around `return` value
-  --> $DIR/lint-unnecessary-parens.rs:16:12
+  --> $DIR/lint-unnecessary-parens.rs:17:12
    |
 LL |     return (X { y });
    |            ^       ^
@@ -28,7 +28,7 @@ LL +     return X { y };
    |
 
 error: unnecessary parentheses around type
-  --> $DIR/lint-unnecessary-parens.rs:19:46
+  --> $DIR/lint-unnecessary-parens.rs:20:46
    |
 LL | pub fn unused_parens_around_return_type() -> (u32) {
    |                                              ^   ^
@@ -40,7 +40,7 @@ LL + pub fn unused_parens_around_return_type() -> u32 {
    |
 
 error: unnecessary parentheses around block return value
-  --> $DIR/lint-unnecessary-parens.rs:25:9
+  --> $DIR/lint-unnecessary-parens.rs:26:9
    |
 LL |         (5)
    |         ^ ^
@@ -52,7 +52,7 @@ LL +         5
    |
 
 error: unnecessary parentheses around block return value
-  --> $DIR/lint-unnecessary-parens.rs:27:5
+  --> $DIR/lint-unnecessary-parens.rs:28:5
    |
 LL |     (5)
    |     ^ ^
@@ -64,7 +64,7 @@ LL +     5
    |
 
 error: unnecessary parentheses around `if` condition
-  --> $DIR/lint-unnecessary-parens.rs:39:7
+  --> $DIR/lint-unnecessary-parens.rs:40:7
    |
 LL |     if(true) {}
    |       ^    ^
@@ -76,7 +76,7 @@ LL +     if true {}
    |
 
 error: unnecessary parentheses around `while` condition
-  --> $DIR/lint-unnecessary-parens.rs:40:10
+  --> $DIR/lint-unnecessary-parens.rs:41:10
    |
 LL |     while(true) {}
    |          ^    ^
@@ -88,7 +88,7 @@ LL +     while true {}
    |
 
 error: unnecessary parentheses around `for` iterator expression
-  --> $DIR/lint-unnecessary-parens.rs:41:13
+  --> $DIR/lint-unnecessary-parens.rs:42:13
    |
 LL |     for _ in(e) {}
    |             ^ ^
@@ -100,7 +100,7 @@ LL +     for _ in e {}
    |
 
 error: unnecessary parentheses around `match` scrutinee expression
-  --> $DIR/lint-unnecessary-parens.rs:42:10
+  --> $DIR/lint-unnecessary-parens.rs:43:10
    |
 LL |     match(1) { _ => ()}
    |          ^ ^
@@ -112,7 +112,7 @@ LL +     match 1 { _ => ()}
    |
 
 error: unnecessary parentheses around `return` value
-  --> $DIR/lint-unnecessary-parens.rs:43:11
+  --> $DIR/lint-unnecessary-parens.rs:44:11
    |
 LL |     return(1);
    |           ^ ^
@@ -124,7 +124,7 @@ LL +     return 1;
    |
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:74:31
+  --> $DIR/lint-unnecessary-parens.rs:75:31
    |
 LL | pub const CONST_ITEM: usize = (10);
    |                               ^  ^
@@ -136,7 +136,7 @@ LL + pub const CONST_ITEM: usize = 10;
    |
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:75:33
+  --> $DIR/lint-unnecessary-parens.rs:76:33
    |
 LL | pub static STATIC_ITEM: usize = (10);
    |                                 ^  ^
@@ -148,7 +148,7 @@ LL + pub static STATIC_ITEM: usize = 10;
    |
 
 error: unnecessary parentheses around function argument
-  --> $DIR/lint-unnecessary-parens.rs:79:9
+  --> $DIR/lint-unnecessary-parens.rs:80:9
    |
 LL |     bar((true));
    |         ^    ^
@@ -160,7 +160,7 @@ LL +     bar(true);
    |
 
 error: unnecessary parentheses around `if` condition
-  --> $DIR/lint-unnecessary-parens.rs:81:8
+  --> $DIR/lint-unnecessary-parens.rs:82:8
    |
 LL |     if (true) {}
    |        ^    ^
@@ -172,7 +172,7 @@ LL +     if true {}
    |
 
 error: unnecessary parentheses around `while` condition
-  --> $DIR/lint-unnecessary-parens.rs:82:11
+  --> $DIR/lint-unnecessary-parens.rs:83:11
    |
 LL |     while (true) {}
    |           ^    ^
@@ -184,7 +184,7 @@ LL +     while true {}
    |
 
 error: unnecessary parentheses around `match` scrutinee expression
-  --> $DIR/lint-unnecessary-parens.rs:83:11
+  --> $DIR/lint-unnecessary-parens.rs:84:11
    |
 LL |     match (true) {
    |           ^    ^
@@ -196,7 +196,7 @@ LL +     match true {
    |
 
 error: unnecessary parentheses around `let` scrutinee expression
-  --> $DIR/lint-unnecessary-parens.rs:86:16
+  --> $DIR/lint-unnecessary-parens.rs:87:16
    |
 LL |     if let 1 = (1) {}
    |                ^ ^
@@ -208,7 +208,7 @@ LL +     if let 1 = 1 {}
    |
 
 error: unnecessary parentheses around `let` scrutinee expression
-  --> $DIR/lint-unnecessary-parens.rs:87:19
+  --> $DIR/lint-unnecessary-parens.rs:88:19
    |
 LL |     while let 1 = (2) {}
    |                   ^ ^
@@ -220,7 +220,7 @@ LL +     while let 1 = 2 {}
    |
 
 error: unnecessary parentheses around method argument
-  --> $DIR/lint-unnecessary-parens.rs:103:24
+  --> $DIR/lint-unnecessary-parens.rs:104:24
    |
 LL |     X { y: false }.foo((true));
    |                        ^    ^
@@ -232,7 +232,7 @@ LL +     X { y: false }.foo(true);
    |
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:105:18
+  --> $DIR/lint-unnecessary-parens.rs:106:18
    |
 LL |     let mut _a = (0);
    |                  ^ ^
@@ -244,7 +244,7 @@ LL +     let mut _a = 0;
    |
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:106:10
+  --> $DIR/lint-unnecessary-parens.rs:107:10
    |
 LL |     _a = (0);
    |          ^ ^
@@ -256,7 +256,7 @@ LL +     _a = 0;
    |
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:107:11
+  --> $DIR/lint-unnecessary-parens.rs:108:11
    |
 LL |     _a += (1);
    |           ^ ^
@@ -268,7 +268,7 @@ LL +     _a += 1;
    |
 
 error: unnecessary parentheses around pattern
-  --> $DIR/lint-unnecessary-parens.rs:109:8
+  --> $DIR/lint-unnecessary-parens.rs:110:8
    |
 LL |     let(mut _a) = 3;
    |        ^      ^
@@ -280,7 +280,7 @@ LL +     let mut _a = 3;
    |
 
 error: unnecessary parentheses around pattern
-  --> $DIR/lint-unnecessary-parens.rs:110:9
+  --> $DIR/lint-unnecessary-parens.rs:111:9
    |
 LL |     let (mut _a) = 3;
    |         ^      ^
@@ -292,7 +292,7 @@ LL +     let mut _a = 3;
    |
 
 error: unnecessary parentheses around pattern
-  --> $DIR/lint-unnecessary-parens.rs:111:8
+  --> $DIR/lint-unnecessary-parens.rs:112:8
    |
 LL |     let( mut _a) = 3;
    |        ^^      ^
@@ -304,7 +304,7 @@ LL +     let mut _a = 3;
    |
 
 error: unnecessary parentheses around pattern
-  --> $DIR/lint-unnecessary-parens.rs:113:8
+  --> $DIR/lint-unnecessary-parens.rs:114:8
    |
 LL |     let(_a) = 3;
    |        ^  ^
@@ -316,7 +316,7 @@ LL +     let _a = 3;
    |
 
 error: unnecessary parentheses around pattern
-  --> $DIR/lint-unnecessary-parens.rs:114:9
+  --> $DIR/lint-unnecessary-parens.rs:115:9
    |
 LL |     let (_a) = 3;
    |         ^  ^
@@ -328,7 +328,7 @@ LL +     let _a = 3;
    |
 
 error: unnecessary parentheses around pattern
-  --> $DIR/lint-unnecessary-parens.rs:115:8
+  --> $DIR/lint-unnecessary-parens.rs:116:8
    |
 LL |     let( _a) = 3;
    |        ^^  ^
@@ -340,7 +340,7 @@ LL +     let _a = 3;
    |
 
 error: unnecessary parentheses around block return value
-  --> $DIR/lint-unnecessary-parens.rs:121:9
+  --> $DIR/lint-unnecessary-parens.rs:122:9
    |
 LL |         (unit!() - One)
    |         ^             ^
@@ -352,7 +352,7 @@ LL +         unit!() - One
    |
 
 error: unnecessary parentheses around block return value
-  --> $DIR/lint-unnecessary-parens.rs:123:9
+  --> $DIR/lint-unnecessary-parens.rs:124:9
    |
 LL |         (unit![] - One)
    |         ^             ^
@@ -364,7 +364,7 @@ LL +         unit![] - One
    |
 
 error: unnecessary parentheses around block return value
-  --> $DIR/lint-unnecessary-parens.rs:126:9
+  --> $DIR/lint-unnecessary-parens.rs:127:9
    |
 LL |         (unit! {} - One)
    |         ^              ^
@@ -375,5 +375,29 @@ LL -         (unit! {} - One)
 LL +         unit! {} - One
    |
 
-error: aborting due to 31 previous errors
+error: unnecessary parentheses around assigned value
+  --> $DIR/lint-unnecessary-parens.rs:132:14
+   |
+LL |     let _r = (&x);
+   |              ^  ^
+   |
+help: remove these parentheses
+   |
+LL -     let _r = (&x);
+LL +     let _r = &x;
+   |
+
+error: unnecessary parentheses around assigned value
+  --> $DIR/lint-unnecessary-parens.rs:133:14
+   |
+LL |     let _r = (&mut x);
+   |              ^      ^
+   |
+help: remove these parentheses
+   |
+LL -     let _r = (&mut x);
+LL +     let _r = &mut x;
+   |
+
+error: aborting due to 33 previous errors