From 792f48c976f006d75229a52441f1a3604c2d0335 Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Mon, 30 Oct 2017 23:31:08 +0900
Subject: [PATCH 1/3] Add a test for #2099

---
 tests/source/match.rs | 10 ++++++++++
 tests/target/match.rs |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/tests/source/match.rs b/tests/source/match.rs
index 527ceea06ef..48a710e6f06 100644
--- a/tests/source/match.rs
+++ b/tests/source/match.rs
@@ -415,3 +415,13 @@ fn match_with_trailing_spaces() {
         None => 1,
     }
 }
+
+fn issue_2099() {
+    let a = match x {
+};
+    let b = match x {
+        
+    };
+
+    match x {}
+}
diff --git a/tests/target/match.rs b/tests/target/match.rs
index e42b1e3428b..3d879d18c20 100644
--- a/tests/target/match.rs
+++ b/tests/target/match.rs
@@ -456,3 +456,10 @@ fn match_with_trailing_spaces() {
         None => 1,
     }
 }
+
+fn issue_2099() {
+    let a = match x {};
+    let b = match x {};
+
+    match x {}
+}

From e84e01c4428d1a16c04597e963d16bdb6427e9c7 Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Mon, 30 Oct 2017 23:31:20 +0900
Subject: [PATCH 2/3] Use context.budget()

---
 src/expr.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/expr.rs b/src/expr.rs
index 9a020646927..67f8af1abbd 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -1450,9 +1450,8 @@ fn rewrite_match(
 
     // Do not take the rhs overhead from the upper expressions into account
     // when rewriting match condition.
-    let new_width = context.config.max_width().checked_sub(shape.used_width())?;
     let cond_shape = Shape {
-        width: new_width,
+        width: context.budget(shape.used_width()),
         ..shape
     };
     // 6 = `match `

From 2e06dea146eddea8a7fc4ad22f12cfe8fd9e1eed Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Mon, 30 Oct 2017 23:36:42 +0900
Subject: [PATCH 3/3] Format match expr with empty body

---
 src/expr.rs | 41 +++++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/src/expr.rs b/src/expr.rs
index 67f8af1abbd..212f05b52b8 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -1444,10 +1444,6 @@ fn rewrite_match(
     span: Span,
     attrs: &[ast::Attribute],
 ) -> Option<String> {
-    if arms.is_empty() {
-        return None;
-    }
-
     // Do not take the rhs overhead from the upper expressions into account
     // when rewriting match condition.
     let cond_shape = Shape {
@@ -1484,9 +1480,12 @@ fn rewrite_match(
     };
 
     let open_brace_pos = if inner_attrs.is_empty() {
-        context
-            .codemap
-            .span_after(mk_sp(cond.span.hi(), arms[0].span().lo()), "{")
+        let hi = if arms.is_empty() {
+            span.hi()
+        } else {
+            arms[0].span().lo()
+        };
+        context.codemap.span_after(mk_sp(cond.span.hi(), hi), "{")
     } else {
         inner_attrs[inner_attrs.len() - 1].span().hi()
     };
@@ -1497,15 +1496,25 @@ fn rewrite_match(
         shape.indent.to_string(context.config)
     };
 
-    Some(format!(
-        "match {}{}{{\n{}{}{}\n{}}}",
-        cond_str,
-        block_sep,
-        inner_attrs_str,
-        arm_indent_str,
-        rewrite_match_arms(context, arms, shape, span, open_brace_pos,)?,
-        shape.indent.to_string(context.config),
-    ))
+    if arms.is_empty() {
+        let snippet = context.snippet(mk_sp(open_brace_pos, span.hi() - BytePos(1)));
+        if snippet.trim().is_empty() {
+            Some(format!("match {} {{}}", cond_str))
+        } else {
+            // Empty match with comments or inner attributes? We are not going to bother, sorry ;)
+            Some(context.snippet(span))
+        }
+    } else {
+        Some(format!(
+            "match {}{}{{\n{}{}{}\n{}}}",
+            cond_str,
+            block_sep,
+            inner_attrs_str,
+            arm_indent_str,
+            rewrite_match_arms(context, arms, shape, span, open_brace_pos)?,
+            shape.indent.to_string(context.config),
+        ))
+    }
 }
 
 fn arm_comma(config: &Config, body: &ast::Expr, is_last: bool) -> &'static str {