From d8301050a539a184b25878c913a5651cfdcaa7d1 Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Thu, 30 Aug 2018 23:38:40 +0900
Subject: [PATCH 1/2] Add a test for #2956

---
 tests/source/fn-simple.rs | 5 +++++
 tests/target/fn-simple.rs | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/tests/source/fn-simple.rs b/tests/source/fn-simple.rs
index 7afc0a1d201a..855332d137d3 100644
--- a/tests/source/fn-simple.rs
+++ b/tests/source/fn-simple.rs
@@ -67,3 +67,8 @@ pub(crate) fn init() {}
 
 // #2630
 fn make_map<T, F: (Fn(&T) -> String)>(records: &Vec<T>, key_fn: F) -> HashMap<String, usize> {}
+
+// #2956
+fn bar(beans: Asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf, spam: bool, eggs: bool) -> bool{
+    unimplemented!();
+}
diff --git a/tests/target/fn-simple.rs b/tests/target/fn-simple.rs
index 60b18a978ed9..f35c5d8a0ed2 100644
--- a/tests/target/fn-simple.rs
+++ b/tests/target/fn-simple.rs
@@ -108,3 +108,12 @@ pub(crate) fn init() {}
 
 // #2630
 fn make_map<T, F: (Fn(&T) -> String)>(records: &Vec<T>, key_fn: F) -> HashMap<String, usize> {}
+
+// #2956
+fn bar(
+    beans: Asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf,
+    spam: bool,
+    eggs: bool,
+) -> bool {
+    unimplemented!();
+}

From ad903e08fdaac65a7567c952a1191a14413ec00d Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Thu, 30 Aug 2018 23:39:39 +0900
Subject: [PATCH 2/2] Keep formatting fn even if there is an unformattable
 argument

---
 src/items.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/items.rs b/src/items.rs
index ff635137e42d..7f8980dd1506 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -2232,8 +2232,10 @@ fn rewrite_args(
 ) -> Option<String> {
     let mut arg_item_strs = args
         .iter()
-        .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
-        .collect::<Option<Vec<_>>>()?;
+        .map(|arg| {
+            arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
+                .unwrap_or_else(|| context.snippet(arg.span()).to_owned())
+        }).collect::<Vec<_>>();
 
     // Account for sugary self.
     // FIXME: the comment for the self argument is dropped. This is blocked