5 files changed, 21 insertions, 15 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 43458f60e..b3172dc28 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -409,7 +409,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "join_to_string"
-version = "0.1.1"
+version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -646,7 +646,7 @@ version = "0.1.0"
 dependencies = [
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "join_to_string 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_ide_api_light 0.1.0",
  "ra_syntax 0.1.0",
  "tools 0.1.0",
@@ -672,6 +672,7 @@ dependencies = [
  "arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "ena 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "flexi_logger 0.10.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_arena 0.1.0",
@@ -709,7 +710,7 @@ name = "ra_ide_api_light"
 version = "0.1.0"
 dependencies = [
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "join_to_string 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "proptest 0.8.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_syntax 0.1.0",
  "ra_text_edit 0.1.0",
@@ -1531,7 +1532,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7e81a7c05f79578dbc15793d8b619db9ba32b4577003ef3af1a91c416798c58d"
 "checksum itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5b8467d9c1cebe26feb08c640139247fac215782d35371ade9a2136ed6085358"
 "checksum itoa 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "1306f3464951f30e30d12373d31c79fbd52d236e5e896fd92f96ec7babbbe60b"
-"checksum join_to_string 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7bddc885f3fd69dd4b5d747c2efe6dd2c36d795ea9938281ed50910e32c95e31"
+"checksum join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4dc7a5290e8c2606ce2be49f456d50f69173cb96d1541e4f66e34ac8b331a98f"
 "checksum languageserver-types 0.53.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7c01845f71b8b3b3557a8179af4434a4b2570829da12371f05272d28183a06ce"
 "checksum lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a374c89b9db55895453a74c1e38861d9deec0b01b405a82516e9d5de4820dea1"
 "checksum libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)" = "023a4cd09b2ff695f9734c1934145a315594b7986398496841c7031a5a1bbdbd"
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index 5a8fdbfc6..0135e0e16 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -12,6 +12,7 @@ salsa = "0.9.1"
 rustc-hash = "1.0"
 parking_lot = "0.7.0"
 ena = "0.11"
+join_to_string = "0.1.3"
 ra_syntax = { path = "../ra_syntax" }
 ra_arena = { path = "../ra_arena" }
 ra_db = { path = "../ra_db" }
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 3b2bfd67a..eb7764f65 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -25,6 +25,7 @@ use std::{fmt, mem};
 use log;
 use ena::unify::{InPlaceUnificationTable, UnifyKey, UnifyValue, NoError};
 use ra_arena::map::ArenaMap;
+use join_to_string::join;
 
 use ra_db::Cancelable;
 
@@ -396,18 +397,21 @@ impl fmt::Display for Ty {
             Ty::Ref(t, m) => write!(f, "&{}{}", m.as_keyword_for_ref(), t),
             Ty::Never => write!(f, "!"),
             Ty::Tuple(ts) => {
-                write!(f, "(")?;
-                for t in ts.iter() {
-                    write!(f, "{},", t)?;
+                if ts.len() == 1 {
+                    write!(f, "({},)", ts[0])
+                } else {
+                    join(ts.iter())
+                        .surround_with("(", ")")
+                        .separator(", ")
+                        .to_fmt(f)
                 }
-                write!(f, ")")
             }
             Ty::FnPtr(sig) => {
-                write!(f, "fn(")?;
-                for t in &sig.input {
-                    write!(f, "{},", t)?;
-                }
-                write!(f, ") -> {}", sig.output)
+                join(sig.input.iter())
+                    .surround_with("fn(", ")")
+                    .separator(", ")
+                    .to_fmt(f)?;
+                write!(f, " -> {}", sig.output)
             }
             Ty::Adt { name, .. } => write!(f, "{}", name),
             Ty::Unknown => write!(f, "[unknown]"),
diff --git a/crates/ra_hir/src/ty/tests/data/backwards.txt b/crates/ra_hir/src/ty/tests/data/backwards.txt
index b6807fb2a..b8593cfd1 100644
--- a/crates/ra_hir/src/ty/tests/data/backwards.txt
+++ b/crates/ra_hir/src/ty/tests/data/backwards.txt
@@ -4,7 +4,7 @@
 [88; 89) 'a': u32
 [92; 108) 'unknow...nction': [unknown]
 [92; 110) 'unknow...tion()': u32
-[116; 125) 'takes_u32': fn(u32,) -> ()
+[116; 125) 'takes_u32': fn(u32) -> ()
 [116; 128) 'takes_u32(a)': ()
 [126; 127) 'a': u32
 [138; 139) 'b': i32
diff --git a/crates/ra_hir/src/ty/tests/data/binary_op.txt b/crates/ra_hir/src/ty/tests/data/binary_op.txt
index 0fb9dc097..8a515ac5e 100644
--- a/crates/ra_hir/src/ty/tests/data/binary_op.txt
+++ b/crates/ra_hir/src/ty/tests/data/binary_op.txt
@@ -22,7 +22,7 @@
 [166; 188) 'minus_...ONST_2': bool
 [181; 188) 'CONST_2': isize
 [198; 199) 'c': i32
-[202; 203) 'f': fn(bool,) -> i32
+[202; 203) 'f': fn(bool) -> i32
 [202; 211) 'f(z || y)': i32
 [202; 215) 'f(z || y) + 5': i32
 [204; 205) 'z': bool