fix a bug while we're at it

Author: ada4a

clippy_lints/src/double_parens.rs

@@ -42,27 +42,25 @@ declare_lint_pass!(DoubleParens => [DOUBLE_PARENS]);
 
 impl EarlyLintPass for DoubleParens {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if expr.span.from_expansion() {
-            return;
-        }
-
         match &expr.kind {
             // ((..))
             // ^^^^^^ expr
             //  ^^^^  inner
             ExprKind::Paren(inner) if matches!(inner.kind, ExprKind::Paren(_) | ExprKind::Tup(_)) => {
                 // suggest removing the outer parens
-                let mut applicability = Applicability::MachineApplicable;
-                let sugg = snippet_with_applicability(cx.sess(), inner.span, "_", &mut applicability);
-                span_lint_and_sugg(
-                    cx,
-                    DOUBLE_PARENS,
-                    expr.span,
-                    "unnecessary parentheses",
-                    "remove them",
-                    sugg.to_string(),
-                    applicability,
-                );
+                if expr.span.eq_ctxt(inner.span) {
+                    let mut applicability = Applicability::MachineApplicable;
+                    let sugg = snippet_with_applicability(cx.sess(), inner.span, "_", &mut applicability);
+                    span_lint_and_sugg(
+                        cx,
+                        DOUBLE_PARENS,
+                        expr.span,
+                        "unnecessary parentheses",
+                        "remove them",
+                        sugg.to_string(),
+                        applicability,
+                    );
+                }
                 return;
             },
 
@@ -75,17 +73,19 @@ impl EarlyLintPass for DoubleParens {
                     && let ExprKind::Paren(inner) = &arg.kind =>
             {
                 // suggest removing the inner parens
-                let mut applicability = Applicability::MachineApplicable;
-                let sugg = snippet_with_applicability(cx.sess(), inner.span, "_", &mut applicability);
-                span_lint_and_sugg(
-                    cx,
-                    DOUBLE_PARENS,
-                    arg.span,
-                    "unnecessary parentheses",
-                    "remove them",
-                    sugg.to_string(),
-                    applicability,
-                );
+                if expr.span.eq_ctxt(arg.span) && arg.span.eq_ctxt(inner.span) {
+                    let mut applicability = Applicability::MachineApplicable;
+                    let sugg = snippet_with_applicability(cx.sess(), inner.span, "_", &mut applicability);
+                    span_lint_and_sugg(
+                        cx,
+                        DOUBLE_PARENS,
+                        arg.span,
+                        "unnecessary parentheses",
+                        "remove them",
+                        sugg.to_string(),
+                        applicability,
+                    );
+                }
             },
             _ => {},
         };

tests/ui/double_parens.fixed

@@ -5,6 +5,7 @@
 
 fn dummy_fn<T>(_: T) {}
 
+#[derive(Clone, Copy)]
 struct DummyStruct;
 
 impl DummyStruct {
@@ -60,4 +61,29 @@ fn inside_macro() {
     //~^ double_parens
 }
 
+fn issue9000(x: DummyStruct) {
+    macro_rules! foo {
+        () => {(100)}
+    }
+    // don't lint: the inner paren comes from the macro expansion
+    (foo!());
+    dummy_fn(foo!());
+    x.dummy_method(foo!());
+
+    macro_rules! baz {
+        ($n:literal) => {($n)}
+    }
+    // don't lint: don't get confused by the expression inside the inner paren
+    // having the same context as the overall expression
+    dummy_fn(baz!(100));
+    x.dummy_method(baz!(100));
+
+    // should lint: both parens are inside the macro
+    macro_rules! bar {
+        () => {(100)}
+        //~^ double_parens
+    }
+    bar!();
+}
+
 fn main() {}

tests/ui/double_parens.rs

@@ -5,6 +5,7 @@
 
 fn dummy_fn<T>(_: T) {}
 
+#[derive(Clone, Copy)]
 struct DummyStruct;
 
 impl DummyStruct {
@@ -60,4 +61,29 @@ fn inside_macro() {
     //~^ double_parens
 }
 
+fn issue9000(x: DummyStruct) {
+    macro_rules! foo {
+        () => {(100)}
+    }
+    // don't lint: the inner paren comes from the macro expansion
+    (foo!());
+    dummy_fn(foo!());
+    x.dummy_method(foo!());
+
+    macro_rules! baz {
+        ($n:literal) => {($n)}
+    }
+    // don't lint: don't get confused by the expression inside the inner paren
+    // having the same context as the overall expression
+    dummy_fn(baz!(100));
+    x.dummy_method(baz!(100));
+
+    // should lint: both parens are inside the macro
+    macro_rules! bar {
+        () => {((100))}
+        //~^ double_parens
+    }
+    bar!();
+}
+
 fn main() {}

tests/ui/double_parens.stderr

@@ -1,5 +1,5 @@
 error: unnecessary parentheses
-  --> tests/ui/double_parens.rs:15:5
+  --> tests/ui/double_parens.rs:16:5
    |
 LL |     ((0))
    |     ^^^^^ help: remove them: `(0)`
@@ -8,34 +8,45 @@ LL |     ((0))
    = help: to override `-D warnings` add `#[allow(clippy::double_parens)]`
 
 error: unnecessary parentheses
-  --> tests/ui/double_parens.rs:20:14
+  --> tests/ui/double_parens.rs:21:14
    |
 LL |     dummy_fn((0));
    |              ^^^ help: remove them: `0`
 
 error: unnecessary parentheses
-  --> tests/ui/double_parens.rs:25:20
+  --> tests/ui/double_parens.rs:26:20
    |
 LL |     x.dummy_method((0));
    |                    ^^^ help: remove them: `0`
 
 error: unnecessary parentheses
-  --> tests/ui/double_parens.rs:30:5
+  --> tests/ui/double_parens.rs:31:5
    |
 LL |     ((1, 2))
    |     ^^^^^^^^ help: remove them: `(1, 2)`
 
 error: unnecessary parentheses
-  --> tests/ui/double_parens.rs:36:5
+  --> tests/ui/double_parens.rs:37:5
    |
 LL |     (())
    |     ^^^^ help: remove them: `()`
 
 error: unnecessary parentheses
-  --> tests/ui/double_parens.rs:59:16
+  --> tests/ui/double_parens.rs:60:16
    |
 LL |     assert_eq!(((1, 2)), (1, 2), "Error");
    |                ^^^^^^^^ help: remove them: `(1, 2)`
 
-error: aborting due to 6 previous errors
+error: unnecessary parentheses
+  --> tests/ui/double_parens.rs:83:16
+   |
+LL |         () => {((100))}
+   |                ^^^^^^^ help: remove them: `(100)`
+...
+LL |     bar!();
+   |     ------ in this macro invocation
+   |
+   = note: this error originates in the macro `bar` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 7 previous errors