From 3aa99020250e1369dfac10952625d4ad6d9d8190 Mon Sep 17 00:00:00 2001
From: Georg Semmler <georg_semmler_05@web.de>
Date: Tue, 3 Dec 2019 12:35:09 +0100
Subject: [PATCH] Fix #66295

---
 src/librustc_lint/unused.rs                   |  8 +++++--
 src/test/ui/lint/lint-unnecessary-parens.rs   |  9 ++++++++
 .../ui/lint/lint-unnecessary-parens.stderr    | 22 +++++++++----------
 3 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index f7de7ec7e18..25c351f6234 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -17,7 +17,7 @@
 use syntax::symbol::{kw, sym};
 use syntax::symbol::Symbol;
 use syntax::util::parser;
-use syntax_pos::{Span, BytePos};
+use syntax_pos::{MultiSpan, Span, BytePos};
 
 use log::debug;
 
@@ -355,7 +355,11 @@ fn check_unused_parens_expr(&self,
         match value.kind {
             ast::ExprKind::Paren(ref inner) => {
                 if !Self::is_expr_parens_necessary(inner, followed_by_block) &&
-                    value.attrs.is_empty() {
+                    value.attrs.is_empty() &&
+                    !MultiSpan::from(value.span).primary_span()
+                        .map(|span| span.from_expansion())
+                        .unwrap_or(false)
+                {
                     let expr_text = if let Ok(snippet) = cx.sess().source_map()
                         .span_to_snippet(value.span) {
                             snippet
diff --git a/src/test/ui/lint/lint-unnecessary-parens.rs b/src/test/ui/lint/lint-unnecessary-parens.rs
index 9f42b855a87..12ffb6d3c66 100644
--- a/src/test/ui/lint/lint-unnecessary-parens.rs
+++ b/src/test/ui/lint/lint-unnecessary-parens.rs
@@ -25,6 +25,12 @@ fn passes_unused_parens_lint() -> &'static (dyn Trait) {
     panic!()
 }
 
+macro_rules! baz {
+    ($($foo:expr),+) => {
+        ($($foo),*)
+    }
+}
+
 fn main() {
     foo();
     bar((true)); //~ ERROR unnecessary parentheses around function argument
@@ -55,4 +61,7 @@ fn main() {
     let mut _a = (0); //~ ERROR unnecessary parentheses around assigned value
     _a = (0); //~ ERROR unnecessary parentheses around assigned value
     _a += (1); //~ ERROR unnecessary parentheses around assigned value
+
+    let _a = baz!(3, 4);
+    let _b = baz!(3);
 }
diff --git a/src/test/ui/lint/lint-unnecessary-parens.stderr b/src/test/ui/lint/lint-unnecessary-parens.stderr
index adc1069b64d..541ae7aa4b5 100644
--- a/src/test/ui/lint/lint-unnecessary-parens.stderr
+++ b/src/test/ui/lint/lint-unnecessary-parens.stderr
@@ -23,25 +23,25 @@ LL | fn unused_parens_around_return_type() -> (u32) {
    |                                          ^^^^^ help: remove these parentheses
 
 error: unnecessary parentheses around function argument
-  --> $DIR/lint-unnecessary-parens.rs:30:9
+  --> $DIR/lint-unnecessary-parens.rs:36:9
    |
 LL |     bar((true));
    |         ^^^^^^ help: remove these parentheses
 
 error: unnecessary parentheses around `if` condition
-  --> $DIR/lint-unnecessary-parens.rs:32:8
+  --> $DIR/lint-unnecessary-parens.rs:38:8
    |
 LL |     if (true) {}
    |        ^^^^^^ help: remove these parentheses
 
 error: unnecessary parentheses around `while` condition
-  --> $DIR/lint-unnecessary-parens.rs:33:11
+  --> $DIR/lint-unnecessary-parens.rs:39:11
    |
 LL |     while (true) {}
    |           ^^^^^^ help: remove these parentheses
 
 warning: denote infinite loops with `loop { ... }`
-  --> $DIR/lint-unnecessary-parens.rs:33:5
+  --> $DIR/lint-unnecessary-parens.rs:39:5
    |
 LL |     while (true) {}
    |     ^^^^^^^^^^^^ help: use `loop`
@@ -49,43 +49,43 @@ LL |     while (true) {}
    = note: `#[warn(while_true)]` on by default
 
 error: unnecessary parentheses around `match` head expression
-  --> $DIR/lint-unnecessary-parens.rs:35:11
+  --> $DIR/lint-unnecessary-parens.rs:41:11
    |
 LL |     match (true) {
    |           ^^^^^^ help: remove these parentheses
 
 error: unnecessary parentheses around `let` head expression
-  --> $DIR/lint-unnecessary-parens.rs:38:16
+  --> $DIR/lint-unnecessary-parens.rs:44:16
    |
 LL |     if let 1 = (1) {}
    |                ^^^ help: remove these parentheses
 
 error: unnecessary parentheses around `let` head expression
-  --> $DIR/lint-unnecessary-parens.rs:39:19
+  --> $DIR/lint-unnecessary-parens.rs:45:19
    |
 LL |     while let 1 = (2) {}
    |                   ^^^ help: remove these parentheses
 
 error: unnecessary parentheses around method argument
-  --> $DIR/lint-unnecessary-parens.rs:53:24
+  --> $DIR/lint-unnecessary-parens.rs:59:24
    |
 LL |     X { y: false }.foo((true));
    |                        ^^^^^^ help: remove these parentheses
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:55:18
+  --> $DIR/lint-unnecessary-parens.rs:61:18
    |
 LL |     let mut _a = (0);
    |                  ^^^ help: remove these parentheses
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:56:10
+  --> $DIR/lint-unnecessary-parens.rs:62:10
    |
 LL |     _a = (0);
    |          ^^^ help: remove these parentheses
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:57:11
+  --> $DIR/lint-unnecessary-parens.rs:63:11
    |
 LL |     _a += (1);
    |           ^^^ help: remove these parentheses