Fix double_parens false positive

Closes #3206

clippy_lints/src/double_parens.rs

@@ -1,7 +1,8 @@
 use crate::syntax::ast::*;
 use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
 use crate::rustc::{declare_tool_lint, lint_array};
-use crate::utils::span_lint;
+use crate::utils::{in_macro, span_lint};
+
 
 /// **What it does:** Checks for unnecessary double parentheses.
 ///
@@ -33,6 +34,10 @@ impl LintPass for DoubleParens {
 
 impl EarlyLintPass for DoubleParens {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
+        if in_macro(expr.span) {
+            return;
+        }
+
         match expr.node {
             ExprKind::Paren(ref in_paren) => match in_paren.node {
                 ExprKind::Paren(_) | ExprKind::Tup(_) => {

tests/ui/double_parens.rs

@@ -48,4 +48,10 @@ fn method_unit_ok(x: DummyStruct) {
     x.dummy_method(());
 }
 
+// Issue #3206
+fn inside_macro() {
+    assert_eq!((1, 2), (1, 2), "Error");
+    assert_eq!(((1, 2)), (1, 2), "Error");
+}
+
 fn main() {}

tests/ui/double_parens.stderr

@@ -30,5 +30,11 @@ error: Consider removing unnecessary double parentheses
 32 |     (())
    |     ^^^^
 
-error: aborting due to 5 previous errors
+error: Consider removing unnecessary double parentheses
+  --> $DIR/double_parens.rs:54:16
+   |
+54 |     assert_eq!(((1, 2)), (1, 2), "Error");
+   |                ^^^^^^^^
+
+error: aborting due to 6 previous errors