From 1f65dc07705e9463ffed0395894f1e7d63cec515 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sun, 30 Dec 2018 13:55:00 -0800
Subject: [PATCH 1/4] Point at the return type span on type mismatch due to
 missing return

Do not point at the entire block span on fn return type mismatches
caused by missing return.
---
 src/librustc/hir/map/mod.rs                   |  3 +-
 src/librustc_typeck/check/mod.rs              | 12 ++++++-
 .../consider-removing-last-semi.stderr        | 28 +++++++--------
 src/test/ui/block-result/issue-11714.stderr   | 15 ++++----
 src/test/ui/block-result/issue-13428.stderr   | 31 +++++++----------
 src/test/ui/break-while-condition.stderr      |  9 ++---
 ...coercion-missing-tail-expected-type.stderr | 24 ++++++-------
 src/test/ui/issues/issue-10536.stderr         |  6 ++--
 src/test/ui/issues/issue-32323.stderr         |  4 +--
 src/test/ui/issues/issue-43162.stderr         | 14 ++++----
 src/test/ui/issues/issue-44023.stderr         |  8 ++---
 src/test/ui/issues/issue-6458-4.stderr        | 12 +++----
 .../ui/liveness/liveness-forgot-ret.stderr    |  4 +--
 .../ui/liveness/liveness-missing-ret2.stderr  | 11 ++----
 .../liveness-return-last-stmt-semi.stderr     | 34 ++++++++-----------
 src/test/ui/missing/missing-return.stderr     |  4 +--
 16 files changed, 96 insertions(+), 123 deletions(-)

diff --git a/src/librustc/hir/map/mod.rs b/src/librustc/hir/map/mod.rs
index 188d487d64485..5bcbeeefa5030 100644
--- a/src/librustc/hir/map/mod.rs
+++ b/src/librustc/hir/map/mod.rs
@@ -667,6 +667,7 @@ impl<'hir> Map<'hir> {
                 Node::Item(_) |
                 Node::ForeignItem(_) |
                 Node::TraitItem(_) |
+                Node::Expr(Expr { node: ExprKind::Closure(..), ..}) |
                 Node::ImplItem(_) => true,
                 _ => false,
             }
@@ -675,7 +676,7 @@ impl<'hir> Map<'hir> {
             match *node {
                 Node::Expr(ref expr) => {
                     match expr.node {
-                        ExprKind::While(..) | ExprKind::Loop(..) => true,
+                        ExprKind::While(..) | ExprKind::Loop(..) | ExprKind::Ret(..) => true,
                         _ => false,
                     }
                 }
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 39beb2832851b..aa13087b484ac 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4791,7 +4791,17 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 // #41425 -- label the implicit `()` as being the
                 // "found type" here, rather than the "expected type".
                 if !self.diverges.get().always() {
-                    coerce.coerce_forced_unit(self, &self.misc(blk.span), &mut |err| {
+                    // #50009 -- Do not point at the entire fn block span, point at the return type
+                    // span, as it is the cause of the requirement, and
+                    // `consider_hint_about_removing_semicolon` will point at the last expression
+                    // if it were a relevant part of the error. This improves usability in editors
+                    // that highlight errors inline.
+                    let sp = if let Some((decl, _)) = self.get_fn_decl(blk.id) {
+                        decl.output.span()
+                    } else {
+                        blk.span
+                    };
+                    coerce.coerce_forced_unit(self, &self.misc(sp), &mut |err| {
                         if let Some(expected_ty) = expected.only_has_type(self) {
                             self.consider_hint_about_removing_semicolon(blk,
                                                                         expected_ty,
diff --git a/src/test/ui/block-result/consider-removing-last-semi.stderr b/src/test/ui/block-result/consider-removing-last-semi.stderr
index 870da00680f42..ce8c624cdad45 100644
--- a/src/test/ui/block-result/consider-removing-last-semi.stderr
+++ b/src/test/ui/block-result/consider-removing-last-semi.stderr
@@ -1,27 +1,23 @@
 error[E0308]: mismatched types
-  --> $DIR/consider-removing-last-semi.rs:1:18
+  --> $DIR/consider-removing-last-semi.rs:1:11
    |
-LL |   fn f() -> String {  //~ ERROR mismatched types
-   |  __________________^
-LL | |     0u8;
-LL | |     "bla".to_string();
-   | |                      - help: consider removing this semicolon
-LL | | }
-   | |_^ expected struct `std::string::String`, found ()
+LL | fn f() -> String {  //~ ERROR mismatched types
+   |           ^^^^^^ expected struct `std::string::String`, found ()
+LL |     0u8;
+LL |     "bla".to_string();
+   |                      - help: consider removing this semicolon
    |
    = note: expected type `std::string::String`
               found type `()`
 
 error[E0308]: mismatched types
-  --> $DIR/consider-removing-last-semi.rs:6:18
+  --> $DIR/consider-removing-last-semi.rs:6:11
    |
-LL |   fn g() -> String {  //~ ERROR mismatched types
-   |  __________________^
-LL | |     "this won't work".to_string();
-LL | |     "removeme".to_string();
-   | |                           - help: consider removing this semicolon
-LL | | }
-   | |_^ expected struct `std::string::String`, found ()
+LL | fn g() -> String {  //~ ERROR mismatched types
+   |           ^^^^^^ expected struct `std::string::String`, found ()
+LL |     "this won't work".to_string();
+LL |     "removeme".to_string();
+   |                           - help: consider removing this semicolon
    |
    = note: expected type `std::string::String`
               found type `()`
diff --git a/src/test/ui/block-result/issue-11714.stderr b/src/test/ui/block-result/issue-11714.stderr
index 8bb37395c5cca..cc97eaf8e1ac3 100644
--- a/src/test/ui/block-result/issue-11714.stderr
+++ b/src/test/ui/block-result/issue-11714.stderr
@@ -1,14 +1,11 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-11714.rs:1:18
+  --> $DIR/issue-11714.rs:1:14
    |
-LL |   fn blah() -> i32 { //~ ERROR mismatched types
-   |  __________________^
-LL | |     1
-LL | |
-LL | |     ;
-   | |     - help: consider removing this semicolon
-LL | | }
-   | |_^ expected i32, found ()
+LL | fn blah() -> i32 { //~ ERROR mismatched types
+   |              ^^^ expected i32, found ()
+...
+LL |     ;
+   |     - help: consider removing this semicolon
    |
    = note: expected type `i32`
               found type `()`
diff --git a/src/test/ui/block-result/issue-13428.stderr b/src/test/ui/block-result/issue-13428.stderr
index 516baa8e5f104..d3a2b5131371e 100644
--- a/src/test/ui/block-result/issue-13428.stderr
+++ b/src/test/ui/block-result/issue-13428.stderr
@@ -1,30 +1,23 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-13428.rs:3:20
+  --> $DIR/issue-13428.rs:3:13
    |
-LL |   fn foo() -> String {  //~ ERROR mismatched types
-   |  ____________________^
-LL | |     format!("Hello {}",
-LL | |             "world")
-LL | |     // Put the trailing semicolon on its own line to test that the
-LL | |     // note message gets the offending semicolon exactly
-LL | |     ;
-   | |     - help: consider removing this semicolon
-LL | | }
-   | |_^ expected struct `std::string::String`, found ()
+LL | fn foo() -> String {  //~ ERROR mismatched types
+   |             ^^^^^^ expected struct `std::string::String`, found ()
+...
+LL |     ;
+   |     - help: consider removing this semicolon
    |
    = note: expected type `std::string::String`
               found type `()`
 
 error[E0308]: mismatched types
-  --> $DIR/issue-13428.rs:11:20
+  --> $DIR/issue-13428.rs:11:13
    |
-LL |   fn bar() -> String {  //~ ERROR mismatched types
-   |  ____________________^
-LL | |     "foobar".to_string()
-LL | |     ;
-   | |     - help: consider removing this semicolon
-LL | | }
-   | |_^ expected struct `std::string::String`, found ()
+LL | fn bar() -> String {  //~ ERROR mismatched types
+   |             ^^^^^^ expected struct `std::string::String`, found ()
+LL |     "foobar".to_string()
+LL |     ;
+   |     - help: consider removing this semicolon
    |
    = note: expected type `std::string::String`
               found type `()`
diff --git a/src/test/ui/break-while-condition.stderr b/src/test/ui/break-while-condition.stderr
index 3e81753a4105f..1c48ad630d8b7 100644
--- a/src/test/ui/break-while-condition.stderr
+++ b/src/test/ui/break-while-condition.stderr
@@ -1,11 +1,8 @@
 error[E0308]: mismatched types
-  --> $DIR/break-while-condition.rs:9:20
+  --> $DIR/break-while-condition.rs:3:11
    |
-LL |           let _: ! = { //~ ERROR mismatched types
-   |  ____________________^
-LL | |             'a: while break 'a {};
-LL | |         };
-   | |_________^ expected !, found ()
+LL | fn main() {
+   |           ^ expected !, found ()
    |
    = note: expected type `!`
               found type `()`
diff --git a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
index 18adf9a46cc84..27f0540e36e94 100644
--- a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
+++ b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
@@ -1,25 +1,21 @@
 error[E0308]: mismatched types
-  --> $DIR/coercion-missing-tail-expected-type.rs:3:28
+  --> $DIR/coercion-missing-tail-expected-type.rs:3:24
    |
-LL |   fn plus_one(x: i32) -> i32 { //~ ERROR mismatched types
-   |  ____________________________^
-LL | |     x + 1;
-   | |          - help: consider removing this semicolon
-LL | | }
-   | |_^ expected i32, found ()
+LL | fn plus_one(x: i32) -> i32 { //~ ERROR mismatched types
+   |                        ^^^ expected i32, found ()
+LL |     x + 1;
+   |          - help: consider removing this semicolon
    |
    = note: expected type `i32`
               found type `()`
 
 error[E0308]: mismatched types
-  --> $DIR/coercion-missing-tail-expected-type.rs:7:29
+  --> $DIR/coercion-missing-tail-expected-type.rs:7:13
    |
-LL |   fn foo() -> Result<u8, u64> { //~ ERROR mismatched types
-   |  _____________________________^
-LL | |     Ok(1);
-   | |          - help: consider removing this semicolon
-LL | | }
-   | |_^ expected enum `std::result::Result`, found ()
+LL | fn foo() -> Result<u8, u64> { //~ ERROR mismatched types
+   |             ^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
+LL |     Ok(1);
+   |          - help: consider removing this semicolon
    |
    = note: expected type `std::result::Result<u8, u64>`
               found type `()`
diff --git a/src/test/ui/issues/issue-10536.stderr b/src/test/ui/issues/issue-10536.stderr
index d5caf777cd45e..71f9a83316c1c 100644
--- a/src/test/ui/issues/issue-10536.stderr
+++ b/src/test/ui/issues/issue-10536.stderr
@@ -17,10 +17,10 @@ LL |     assert!({one! two()});
    |              ^^^
 
 error[E0308]: mismatched types
-  --> $DIR/issue-10536.rs:14:13
+  --> $DIR/issue-10536.rs:11:15
    |
-LL |     assert!({one! two()});
-   |             ^^^^^^^^^^^^ expected bool, found ()
+LL | pub fn main() {
+   |               ^ expected bool, found ()
    |
    = note: expected type `bool`
               found type `()`
diff --git a/src/test/ui/issues/issue-32323.stderr b/src/test/ui/issues/issue-32323.stderr
index 00ef2ca18098b..6729fdf726aae 100644
--- a/src/test/ui/issues/issue-32323.stderr
+++ b/src/test/ui/issues/issue-32323.stderr
@@ -1,8 +1,8 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-32323.rs:5:49
+  --> $DIR/issue-32323.rs:5:30
    |
 LL | pub fn f<'a, T: Tr<'a>>() -> <T as Tr<'a>>::Out {}
-   |                                                 ^^ expected associated type, found ()
+   |                              ^^^^^^^^^^^^^^^^^^ expected associated type, found ()
    |
    = note: expected type `<T as Tr<'a>>::Out`
               found type `()`
diff --git a/src/test/ui/issues/issue-43162.stderr b/src/test/ui/issues/issue-43162.stderr
index 8b02476841d2e..d679fbb72624e 100644
--- a/src/test/ui/issues/issue-43162.stderr
+++ b/src/test/ui/issues/issue-43162.stderr
@@ -11,15 +11,13 @@ LL |     break {}; //~ ERROR E0268
    |     ^^^^^^^^ cannot break outside of a loop
 
 error[E0308]: mismatched types
-  --> $DIR/issue-43162.rs:1:18
+  --> $DIR/issue-43162.rs:1:13
    |
-LL |   fn foo() -> bool {
-   |  __________________^
-LL | |     //~^ ERROR E0308
-LL | |     break true; //~ ERROR E0268
-   | |               - help: consider removing this semicolon
-LL | | }
-   | |_^ expected bool, found ()
+LL | fn foo() -> bool {
+   |             ^^^^ expected bool, found ()
+LL |     //~^ ERROR E0308
+LL |     break true; //~ ERROR E0268
+   |               - help: consider removing this semicolon
    |
    = note: expected type `bool`
               found type `()`
diff --git a/src/test/ui/issues/issue-44023.stderr b/src/test/ui/issues/issue-44023.stderr
index 21cfe07e3e6e4..55757c1eb930e 100644
--- a/src/test/ui/issues/issue-44023.stderr
+++ b/src/test/ui/issues/issue-44023.stderr
@@ -1,10 +1,8 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-44023.rs:5:42
+  --> $DIR/issue-44023.rs:5:36
    |
-LL |   fn საჭმელად_გემრიელი_სადილი ( ) -> isize { //~ ERROR mismatched types
-   |  __________________________________________^
-LL | | }
-   | |_^ expected isize, found ()
+LL | fn საჭმელად_გემრიელი_სადილი ( ) -> isize { //~ ERROR mismatched types
+   |                                    ^^^^^ expected isize, found ()
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/issues/issue-6458-4.stderr b/src/test/ui/issues/issue-6458-4.stderr
index 3e621c17cdcb6..e487e15c16c62 100644
--- a/src/test/ui/issues/issue-6458-4.stderr
+++ b/src/test/ui/issues/issue-6458-4.stderr
@@ -1,12 +1,10 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-6458-4.rs:1:40
+  --> $DIR/issue-6458-4.rs:1:20
    |
-LL |   fn foo(b: bool) -> Result<bool,String> { //~ ERROR mismatched types
-   |  ________________________________________^
-LL | |     Err("bar".to_string());
-   | |                           - help: consider removing this semicolon
-LL | | }
-   | |_^ expected enum `std::result::Result`, found ()
+LL | fn foo(b: bool) -> Result<bool,String> { //~ ERROR mismatched types
+   |                    ^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
+LL |     Err("bar".to_string());
+   |                           - help: consider removing this semicolon
    |
    = note: expected type `std::result::Result<bool, std::string::String>`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-forgot-ret.stderr b/src/test/ui/liveness/liveness-forgot-ret.stderr
index b89112259004f..8d0eeb35fc3f1 100644
--- a/src/test/ui/liveness/liveness-forgot-ret.stderr
+++ b/src/test/ui/liveness/liveness-forgot-ret.stderr
@@ -1,8 +1,8 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-forgot-ret.rs:3:25
+  --> $DIR/liveness-forgot-ret.rs:3:19
    |
 LL | fn f(a: isize) -> isize { if god_exists(a) { return 5; }; }
-   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected isize, found ()
+   |                   ^^^^^ expected isize, found ()    - expected because of this statement
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-missing-ret2.stderr b/src/test/ui/liveness/liveness-missing-ret2.stderr
index e5f74786bc608..956b71fcfe8f6 100644
--- a/src/test/ui/liveness/liveness-missing-ret2.stderr
+++ b/src/test/ui/liveness/liveness-missing-ret2.stderr
@@ -1,13 +1,8 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-missing-ret2.rs:1:17
+  --> $DIR/liveness-missing-ret2.rs:1:11
    |
-LL |   fn f() -> isize { //~ ERROR mismatched types
-   |  _________________^
-LL | |     // Make sure typestate doesn't interpret this match expression as
-LL | |     // the function result
-LL | |    match true { true => { } _ => {} };
-LL | | }
-   | |_^ expected isize, found ()
+LL | fn f() -> isize { //~ ERROR mismatched types
+   |           ^^^^^ expected isize, found ()
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
index 3aa81a405a6b5..bb4ca303aa775 100644
--- a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
+++ b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
@@ -1,11 +1,10 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:4:45
+  --> $DIR/liveness-return-last-stmt-semi.rs:4:41
    |
 LL | macro_rules! test { () => { fn foo() -> i32 { 1; } } }
-   |                                             ^^^-^^
-   |                                             |  |
-   |                                             |  help: consider removing this semicolon
-   |                                             expected i32, found ()
+   |                                         ^^^    - help: consider removing this semicolon
+   |                                         |
+   |                                         expected i32, found ()
 ...
 LL |     test!();
    |     -------- in this macro invocation
@@ -14,35 +13,30 @@ LL |     test!();
               found type `()`
 
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:7:23
+  --> $DIR/liveness-return-last-stmt-semi.rs:7:19
    |
 LL | fn no_return() -> i32 {} //~ ERROR mismatched types
-   |                       ^^ expected i32, found ()
+   |                   ^^^ expected i32, found ()
    |
    = note: expected type `i32`
               found type `()`
 
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:9:23
+  --> $DIR/liveness-return-last-stmt-semi.rs:9:19
    |
-LL |   fn bar(x: u32) -> u32 { //~ ERROR mismatched types
-   |  _______________________^
-LL | |     x * 2;
-   | |          - help: consider removing this semicolon
-LL | | }
-   | |_^ expected u32, found ()
+LL | fn bar(x: u32) -> u32 { //~ ERROR mismatched types
+   |                   ^^^ expected u32, found ()
+LL |     x * 2;
+   |          - help: consider removing this semicolon
    |
    = note: expected type `u32`
               found type `()`
 
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:13:23
+  --> $DIR/liveness-return-last-stmt-semi.rs:13:19
    |
-LL |   fn baz(x: u64) -> u32 { //~ ERROR mismatched types
-   |  _______________________^
-LL | |     x * 2;
-LL | | }
-   | |_^ expected u32, found ()
+LL | fn baz(x: u64) -> u32 { //~ ERROR mismatched types
+   |                   ^^^ expected u32, found ()
    |
    = note: expected type `u32`
               found type `()`
diff --git a/src/test/ui/missing/missing-return.stderr b/src/test/ui/missing/missing-return.stderr
index 6d42dafd6f163..be86325de0003 100644
--- a/src/test/ui/missing/missing-return.stderr
+++ b/src/test/ui/missing/missing-return.stderr
@@ -1,8 +1,8 @@
 error[E0308]: mismatched types
-  --> $DIR/missing-return.rs:3:17
+  --> $DIR/missing-return.rs:3:11
    |
 LL | fn f() -> isize { }
-   |                 ^^^ expected isize, found ()
+   |           ^^^^^ expected isize, found ()
    |
    = note: expected type `isize`
               found type `()`

From f62f540b4e81a4e67a39f199948406684a343f4a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sun, 30 Dec 2018 15:41:19 -0800
Subject: [PATCH 2/4] Point at function name span

---
 src/librustc_typeck/check/mod.rs              | 108 ++++++++++--------
 .../consider-removing-last-semi.stderr        |   8 +-
 src/test/ui/block-result/issue-11714.stderr   |   4 +-
 src/test/ui/block-result/issue-13428.stderr   |   8 +-
 src/test/ui/break-while-condition.stderr      |   4 +-
 ...coercion-missing-tail-expected-type.stderr |   8 +-
 src/test/ui/issues/issue-10536.stderr         |   4 +-
 src/test/ui/issues/issue-32323.stderr         |   4 +-
 src/test/ui/issues/issue-43162.stderr         |   4 +-
 src/test/ui/issues/issue-44023.stderr         |   4 +-
 src/test/ui/issues/issue-6458-4.stderr        |   4 +-
 .../liveness-closure-require-ret.stderr       |   6 +-
 .../ui/liveness/liveness-forgot-ret.stderr    |   5 +-
 .../ui/liveness/liveness-issue-2163.stderr    |  11 +-
 .../ui/liveness/liveness-missing-ret2.stderr  |   4 +-
 .../liveness-return-last-stmt-semi.stderr     |  19 ++-
 src/test/ui/missing/missing-return.stderr     |   4 +-
 17 files changed, 132 insertions(+), 77 deletions(-)

diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index aa13087b484ac..381abcb977b26 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4796,16 +4796,20 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                     // `consider_hint_about_removing_semicolon` will point at the last expression
                     // if it were a relevant part of the error. This improves usability in editors
                     // that highlight errors inline.
-                    let sp = if let Some((decl, _)) = self.get_fn_decl(blk.id) {
-                        decl.output.span()
+                    let (sp, fn_span) = if let Some((decl, ident)) = self.get_parent_fn_decl(blk.id) {
+                        (decl.output.span(), Some(ident.span))
                     } else {
-                        blk.span
+                        (blk.span, None)
                     };
                     coerce.coerce_forced_unit(self, &self.misc(sp), &mut |err| {
                         if let Some(expected_ty) = expected.only_has_type(self) {
-                            self.consider_hint_about_removing_semicolon(blk,
-                                                                        expected_ty,
-                                                                        err);
+                            self.consider_hint_about_removing_semicolon(blk, expected_ty, err);
+                        }
+                        if let Some(fn_span) = fn_span {
+                            err.span_label(
+                                fn_span,
+                                "this function's body doesn't return the expected type",
+                            );
                         }
                     }, false);
                 }
@@ -4830,45 +4834,53 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         ty
     }
 
+    /// Given a function block's `NodeId`, return its `FnDecl` , `None` otherwise.
+    fn get_parent_fn_decl(&self, blk_id: ast::NodeId) -> Option<(hir::FnDecl, ast::Ident)> {
+        let parent = self.tcx.hir().get(self.tcx.hir().get_parent(blk_id));
+        self.get_node_fn_decl(parent).map(|(fn_decl, ident , _)| (fn_decl, ident))
+    }
+
+    /// Given a function `Node`, return its `FnDecl` , `None` otherwise.
+    fn get_node_fn_decl(&self, node: Node) -> Option<(hir::FnDecl, ast::Ident, bool)> {
+        if let Node::Item(&hir::Item {
+            ident, node: hir::ItemKind::Fn(ref decl, ..), ..
+        }) = node {
+            decl.clone().and_then(|decl| {
+                // This is less than ideal, it will not suggest a return type span on any
+                // method called `main`, regardless of whether it is actually the entry point,
+                // but it will still present it as the reason for the expected type.
+                Some((decl, ident, ident.name != Symbol::intern("main")))
+            })
+        } else if let Node::TraitItem(&hir::TraitItem {
+            ident, node: hir::TraitItemKind::Method(hir::MethodSig {
+                ref decl, ..
+            }, ..), ..
+        }) = node {
+            decl.clone().and_then(|decl| {
+                Some((decl, ident, true))
+            })
+        } else if let Node::ImplItem(&hir::ImplItem {
+            ident, node: hir::ImplItemKind::Method(hir::MethodSig {
+                ref decl, ..
+            }, ..), ..
+        }) = node {
+            decl.clone().and_then(|decl| {
+                Some((decl, ident, false))
+            })
+        } else {
+            None
+        }
+    }
+
     /// Given a `NodeId`, return the `FnDecl` of the method it is enclosed by and whether a
     /// suggestion can be made, `None` otherwise.
     pub fn get_fn_decl(&self, blk_id: ast::NodeId) -> Option<(hir::FnDecl, bool)> {
         // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or
         // `while` before reaching it, as block tail returns are not available in them.
-        if let Some(fn_id) = self.tcx.hir().get_return_block(blk_id) {
-            let parent = self.tcx.hir().get(fn_id);
-
-            if let Node::Item(&hir::Item {
-                ident, node: hir::ItemKind::Fn(ref decl, ..), ..
-            }) = parent {
-                decl.clone().and_then(|decl| {
-                    // This is less than ideal, it will not suggest a return type span on any
-                    // method called `main`, regardless of whether it is actually the entry point,
-                    // but it will still present it as the reason for the expected type.
-                    Some((decl, ident.name != Symbol::intern("main")))
-                })
-            } else if let Node::TraitItem(&hir::TraitItem {
-                node: hir::TraitItemKind::Method(hir::MethodSig {
-                    ref decl, ..
-                }, ..), ..
-            }) = parent {
-                decl.clone().and_then(|decl| {
-                    Some((decl, true))
-                })
-            } else if let Node::ImplItem(&hir::ImplItem {
-                node: hir::ImplItemKind::Method(hir::MethodSig {
-                    ref decl, ..
-                }, ..), ..
-            }) = parent {
-                decl.clone().and_then(|decl| {
-                    Some((decl, false))
-                })
-            } else {
-                None
-            }
-        } else {
-            None
-        }
+        self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| {
+            let parent = self.tcx.hir().get(blk_id);
+            self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main))
+        })
     }
 
     /// On implicit return expressions with mismatched types, provide the following suggestions:
@@ -4876,13 +4888,15 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
     ///  - Point out the method's return type as the reason for the expected type
     ///  - Possible missing semicolon
     ///  - Possible missing return type if the return type is the default, and not `fn main()`
-    pub fn suggest_mismatched_types_on_tail(&self,
-                                            err: &mut DiagnosticBuilder<'tcx>,
-                                            expression: &'gcx hir::Expr,
-                                            expected: Ty<'tcx>,
-                                            found: Ty<'tcx>,
-                                            cause_span: Span,
-                                            blk_id: ast::NodeId) {
+    pub fn suggest_mismatched_types_on_tail(
+        &self,
+        err: &mut DiagnosticBuilder<'tcx>,
+        expression: &'gcx hir::Expr,
+        expected: Ty<'tcx>,
+        found: Ty<'tcx>,
+        cause_span: Span,
+        blk_id: ast::NodeId,
+    ) {
         self.suggest_missing_semicolon(err, expression, expected, cause_span);
         if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) {
             self.suggest_missing_return_type(err, &fn_decl, expected, found, can_suggest);
diff --git a/src/test/ui/block-result/consider-removing-last-semi.stderr b/src/test/ui/block-result/consider-removing-last-semi.stderr
index ce8c624cdad45..79e7a536cdc83 100644
--- a/src/test/ui/block-result/consider-removing-last-semi.stderr
+++ b/src/test/ui/block-result/consider-removing-last-semi.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/consider-removing-last-semi.rs:1:11
    |
 LL | fn f() -> String {  //~ ERROR mismatched types
-   |           ^^^^^^ expected struct `std::string::String`, found ()
+   |    -      ^^^^^^ expected struct `std::string::String`, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     0u8;
 LL |     "bla".to_string();
    |                      - help: consider removing this semicolon
@@ -14,7 +16,9 @@ error[E0308]: mismatched types
   --> $DIR/consider-removing-last-semi.rs:6:11
    |
 LL | fn g() -> String {  //~ ERROR mismatched types
-   |           ^^^^^^ expected struct `std::string::String`, found ()
+   |    -      ^^^^^^ expected struct `std::string::String`, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     "this won't work".to_string();
 LL |     "removeme".to_string();
    |                           - help: consider removing this semicolon
diff --git a/src/test/ui/block-result/issue-11714.stderr b/src/test/ui/block-result/issue-11714.stderr
index cc97eaf8e1ac3..82253911316ad 100644
--- a/src/test/ui/block-result/issue-11714.stderr
+++ b/src/test/ui/block-result/issue-11714.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-11714.rs:1:14
    |
 LL | fn blah() -> i32 { //~ ERROR mismatched types
-   |              ^^^ expected i32, found ()
+   |    ----      ^^^ expected i32, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 ...
 LL |     ;
    |     - help: consider removing this semicolon
diff --git a/src/test/ui/block-result/issue-13428.stderr b/src/test/ui/block-result/issue-13428.stderr
index d3a2b5131371e..8b8eb825377c4 100644
--- a/src/test/ui/block-result/issue-13428.stderr
+++ b/src/test/ui/block-result/issue-13428.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-13428.rs:3:13
    |
 LL | fn foo() -> String {  //~ ERROR mismatched types
-   |             ^^^^^^ expected struct `std::string::String`, found ()
+   |    ---      ^^^^^^ expected struct `std::string::String`, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 ...
 LL |     ;
    |     - help: consider removing this semicolon
@@ -14,7 +16,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-13428.rs:11:13
    |
 LL | fn bar() -> String {  //~ ERROR mismatched types
-   |             ^^^^^^ expected struct `std::string::String`, found ()
+   |    ---      ^^^^^^ expected struct `std::string::String`, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     "foobar".to_string()
 LL |     ;
    |     - help: consider removing this semicolon
diff --git a/src/test/ui/break-while-condition.stderr b/src/test/ui/break-while-condition.stderr
index 1c48ad630d8b7..6709747b13767 100644
--- a/src/test/ui/break-while-condition.stderr
+++ b/src/test/ui/break-while-condition.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/break-while-condition.rs:3:11
    |
 LL | fn main() {
-   |           ^ expected !, found ()
+   |    ----   ^ expected !, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `!`
               found type `()`
diff --git a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
index 27f0540e36e94..9ace5b8ad3a8d 100644
--- a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
+++ b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/coercion-missing-tail-expected-type.rs:3:24
    |
 LL | fn plus_one(x: i32) -> i32 { //~ ERROR mismatched types
-   |                        ^^^ expected i32, found ()
+   |    --------            ^^^ expected i32, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     x + 1;
    |          - help: consider removing this semicolon
    |
@@ -13,7 +15,9 @@ error[E0308]: mismatched types
   --> $DIR/coercion-missing-tail-expected-type.rs:7:13
    |
 LL | fn foo() -> Result<u8, u64> { //~ ERROR mismatched types
-   |             ^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
+   |    ---      ^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     Ok(1);
    |          - help: consider removing this semicolon
    |
diff --git a/src/test/ui/issues/issue-10536.stderr b/src/test/ui/issues/issue-10536.stderr
index 71f9a83316c1c..02008470e636f 100644
--- a/src/test/ui/issues/issue-10536.stderr
+++ b/src/test/ui/issues/issue-10536.stderr
@@ -20,7 +20,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-10536.rs:11:15
    |
 LL | pub fn main() {
-   |               ^ expected bool, found ()
+   |        ----   ^ expected bool, found ()
+   |        |
+   |        this function's body doesn't return the expected type
    |
    = note: expected type `bool`
               found type `()`
diff --git a/src/test/ui/issues/issue-32323.stderr b/src/test/ui/issues/issue-32323.stderr
index 6729fdf726aae..bef3596103c2b 100644
--- a/src/test/ui/issues/issue-32323.stderr
+++ b/src/test/ui/issues/issue-32323.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-32323.rs:5:30
    |
 LL | pub fn f<'a, T: Tr<'a>>() -> <T as Tr<'a>>::Out {}
-   |                              ^^^^^^^^^^^^^^^^^^ expected associated type, found ()
+   |        -                     ^^^^^^^^^^^^^^^^^^ expected associated type, found ()
+   |        |
+   |        this function's body doesn't return the expected type
    |
    = note: expected type `<T as Tr<'a>>::Out`
               found type `()`
diff --git a/src/test/ui/issues/issue-43162.stderr b/src/test/ui/issues/issue-43162.stderr
index d679fbb72624e..4d2b3549f8ed4 100644
--- a/src/test/ui/issues/issue-43162.stderr
+++ b/src/test/ui/issues/issue-43162.stderr
@@ -14,7 +14,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-43162.rs:1:13
    |
 LL | fn foo() -> bool {
-   |             ^^^^ expected bool, found ()
+   |    ---      ^^^^ expected bool, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     //~^ ERROR E0308
 LL |     break true; //~ ERROR E0268
    |               - help: consider removing this semicolon
diff --git a/src/test/ui/issues/issue-44023.stderr b/src/test/ui/issues/issue-44023.stderr
index 55757c1eb930e..944098a644df2 100644
--- a/src/test/ui/issues/issue-44023.stderr
+++ b/src/test/ui/issues/issue-44023.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-44023.rs:5:36
    |
 LL | fn საჭმელად_გემრიელი_სადილი ( ) -> isize { //~ ERROR mismatched types
-   |                                    ^^^^^ expected isize, found ()
+   |    ------------------------        ^^^^^ expected isize, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/issues/issue-6458-4.stderr b/src/test/ui/issues/issue-6458-4.stderr
index e487e15c16c62..f4cdceac1726a 100644
--- a/src/test/ui/issues/issue-6458-4.stderr
+++ b/src/test/ui/issues/issue-6458-4.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/issue-6458-4.rs:1:20
    |
 LL | fn foo(b: bool) -> Result<bool,String> { //~ ERROR mismatched types
-   |                    ^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
+   |    ---             ^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     Err("bar".to_string());
    |                           - help: consider removing this semicolon
    |
diff --git a/src/test/ui/liveness/liveness-closure-require-ret.stderr b/src/test/ui/liveness/liveness-closure-require-ret.stderr
index 3133efdedd762..d7992704c50e8 100644
--- a/src/test/ui/liveness/liveness-closure-require-ret.stderr
+++ b/src/test/ui/liveness/liveness-closure-require-ret.stderr
@@ -1,8 +1,10 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-closure-require-ret.rs:2:37
+  --> $DIR/liveness-closure-require-ret.rs:2:11
    |
 LL | fn main() { println!("{}", force(|| {})); } //~ ERROR mismatched types
-   |                                     ^^ expected isize, found ()
+   |    ----   ^ expected isize, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-forgot-ret.stderr b/src/test/ui/liveness/liveness-forgot-ret.stderr
index 8d0eeb35fc3f1..578890f5e625f 100644
--- a/src/test/ui/liveness/liveness-forgot-ret.stderr
+++ b/src/test/ui/liveness/liveness-forgot-ret.stderr
@@ -2,7 +2,10 @@ error[E0308]: mismatched types
   --> $DIR/liveness-forgot-ret.rs:3:19
    |
 LL | fn f(a: isize) -> isize { if god_exists(a) { return 5; }; }
-   |                   ^^^^^ expected isize, found ()    - expected because of this statement
+   |    -              ^^^^^                             - expected because of this statement
+   |    |              |
+   |    |              expected isize, found ()
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-issue-2163.stderr b/src/test/ui/liveness/liveness-issue-2163.stderr
index e91994d9a2299..a8a5684207608 100644
--- a/src/test/ui/liveness/liveness-issue-2163.stderr
+++ b/src/test/ui/liveness/liveness-issue-2163.stderr
@@ -1,11 +1,10 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-issue-2163.rs:5:30
+  --> $DIR/liveness-issue-2163.rs:3:11
    |
-LL |       a.iter().all(|_| -> bool {
-   |  ______________________________^
-LL | |         //~^ ERROR mismatched types
-LL | |     });
-   | |_____^ expected bool, found ()
+LL | fn main() {
+   |    ----   ^ expected bool, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `bool`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-missing-ret2.stderr b/src/test/ui/liveness/liveness-missing-ret2.stderr
index 956b71fcfe8f6..201b3ee6861a1 100644
--- a/src/test/ui/liveness/liveness-missing-ret2.stderr
+++ b/src/test/ui/liveness/liveness-missing-ret2.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/liveness-missing-ret2.rs:1:11
    |
 LL | fn f() -> isize { //~ ERROR mismatched types
-   |           ^^^^^ expected isize, found ()
+   |    -      ^^^^^ expected isize, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
index bb4ca303aa775..2ee77f30a6608 100644
--- a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
+++ b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
@@ -2,9 +2,10 @@ error[E0308]: mismatched types
   --> $DIR/liveness-return-last-stmt-semi.rs:4:41
    |
 LL | macro_rules! test { () => { fn foo() -> i32 { 1; } } }
-   |                                         ^^^    - help: consider removing this semicolon
-   |                                         |
-   |                                         expected i32, found ()
+   |                                ---      ^^^    - help: consider removing this semicolon
+   |                                |        |
+   |                                |        expected i32, found ()
+   |                                this function's body doesn't return the expected type
 ...
 LL |     test!();
    |     -------- in this macro invocation
@@ -16,7 +17,9 @@ error[E0308]: mismatched types
   --> $DIR/liveness-return-last-stmt-semi.rs:7:19
    |
 LL | fn no_return() -> i32 {} //~ ERROR mismatched types
-   |                   ^^^ expected i32, found ()
+   |    ---------      ^^^ expected i32, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `i32`
               found type `()`
@@ -25,7 +28,9 @@ error[E0308]: mismatched types
   --> $DIR/liveness-return-last-stmt-semi.rs:9:19
    |
 LL | fn bar(x: u32) -> u32 { //~ ERROR mismatched types
-   |                   ^^^ expected u32, found ()
+   |    ---            ^^^ expected u32, found ()
+   |    |
+   |    this function's body doesn't return the expected type
 LL |     x * 2;
    |          - help: consider removing this semicolon
    |
@@ -36,7 +41,9 @@ error[E0308]: mismatched types
   --> $DIR/liveness-return-last-stmt-semi.rs:13:19
    |
 LL | fn baz(x: u64) -> u32 { //~ ERROR mismatched types
-   |                   ^^^ expected u32, found ()
+   |    ---            ^^^ expected u32, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `u32`
               found type `()`
diff --git a/src/test/ui/missing/missing-return.stderr b/src/test/ui/missing/missing-return.stderr
index be86325de0003..9e6ffd97312f0 100644
--- a/src/test/ui/missing/missing-return.stderr
+++ b/src/test/ui/missing/missing-return.stderr
@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/missing-return.rs:3:11
    |
 LL | fn f() -> isize { }
-   |           ^^^^^ expected isize, found ()
+   |    -      ^^^^^ expected isize, found ()
+   |    |
+   |    this function's body doesn't return the expected type
    |
    = note: expected type `isize`
               found type `()`

From 5d086c328276d428d499284d745a0a1814e8b11c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sun, 30 Dec 2018 21:59:27 -0800
Subject: [PATCH 3/4] Tweak E0308 error for clarity

---
 src/librustc_typeck/check/mod.rs              | 82 +++++++++++--------
 .../consider-removing-last-semi.stderr        |  4 +-
 src/test/ui/block-result/issue-11714.stderr   |  2 +-
 src/test/ui/block-result/issue-13428.stderr   |  4 +-
 src/test/ui/break-while-condition.stderr      | 11 +--
 ...coercion-missing-tail-expected-type.stderr |  4 +-
 src/test/ui/issues/issue-10536.stderr         |  8 +-
 src/test/ui/issues/issue-32323.stderr         |  2 +-
 src/test/ui/issues/issue-43162.stderr         |  2 +-
 src/test/ui/issues/issue-44023.stderr         |  2 +-
 src/test/ui/issues/issue-6458-4.stderr        |  2 +-
 .../liveness-closure-require-ret.stderr       |  6 +-
 .../ui/liveness/liveness-forgot-ret.stderr    |  7 +-
 .../ui/liveness/liveness-issue-2163.stderr    | 11 +--
 .../ui/liveness/liveness-missing-ret2.stderr  |  2 +-
 .../liveness-return-last-stmt-semi.stderr     |  8 +-
 src/test/ui/missing/missing-return.stderr     |  2 +-
 17 files changed, 87 insertions(+), 72 deletions(-)

diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 381abcb977b26..9492b1a2341dc 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4796,20 +4796,26 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                     // `consider_hint_about_removing_semicolon` will point at the last expression
                     // if it were a relevant part of the error. This improves usability in editors
                     // that highlight errors inline.
-                    let (sp, fn_span) = if let Some((decl, ident)) = self.get_parent_fn_decl(blk.id) {
-                        (decl.output.span(), Some(ident.span))
-                    } else {
-                        (blk.span, None)
-                    };
+                    let mut sp = blk.span;
+                    let mut fn_span = None;
+                    if let Some((decl, ident)) = self.get_parent_fn_decl(blk.id) {
+                        let ret_sp = decl.output.span();
+                        if let Some(block_sp) = self.parent_item_span(blk.id) {
+                            // HACK: on some cases (`ui/liveness/liveness-issue-2163.rs`) the
+                            // output would otherwise be incorrect and even misleading. Make sure
+                            // the span we're aiming at correspond to a `fn` body.
+                            if block_sp == blk.span {
+                                sp = ret_sp;
+                                fn_span = Some(ident.span);
+                            }
+                        }
+                    }
                     coerce.coerce_forced_unit(self, &self.misc(sp), &mut |err| {
                         if let Some(expected_ty) = expected.only_has_type(self) {
                             self.consider_hint_about_removing_semicolon(blk, expected_ty, err);
                         }
                         if let Some(fn_span) = fn_span {
-                            err.span_label(
-                                fn_span,
-                                "this function's body doesn't return the expected type",
-                            );
+                            err.span_label(fn_span, "this function's body doesn't return");
                         }
                     }, false);
                 }
@@ -4834,6 +4840,25 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         ty
     }
 
+    fn parent_item_span(&self, id: ast::NodeId) -> Option<Span> {
+        let node = self.tcx.hir().get(self.tcx.hir().get_parent(id));
+        match node {
+            Node::Item(&hir::Item {
+                node: hir::ItemKind::Fn(_, _, _, body_id), ..
+            }) |
+            Node::ImplItem(&hir::ImplItem {
+                node: hir::ImplItemKind::Method(_, body_id), ..
+            }) => {
+                let body = self.tcx.hir().body(body_id);
+                if let ExprKind::Block(block, _) = &body.value.node {
+                    return Some(block.span);
+                }
+            }
+            _ => {}
+        }
+        None
+    }
+
     /// Given a function block's `NodeId`, return its `FnDecl` , `None` otherwise.
     fn get_parent_fn_decl(&self, blk_id: ast::NodeId) -> Option<(hir::FnDecl, ast::Ident)> {
         let parent = self.tcx.hir().get(self.tcx.hir().get_parent(blk_id));
@@ -4842,33 +4867,26 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
 
     /// Given a function `Node`, return its `FnDecl` , `None` otherwise.
     fn get_node_fn_decl(&self, node: Node) -> Option<(hir::FnDecl, ast::Ident, bool)> {
-        if let Node::Item(&hir::Item {
-            ident, node: hir::ItemKind::Fn(ref decl, ..), ..
-        }) = node {
-            decl.clone().and_then(|decl| {
+        match node {
+            Node::Item(&hir::Item {
+                ident, node: hir::ItemKind::Fn(ref decl, ..), ..
+            }) => decl.clone().and_then(|decl| {
                 // This is less than ideal, it will not suggest a return type span on any
                 // method called `main`, regardless of whether it is actually the entry point,
                 // but it will still present it as the reason for the expected type.
                 Some((decl, ident, ident.name != Symbol::intern("main")))
-            })
-        } else if let Node::TraitItem(&hir::TraitItem {
-            ident, node: hir::TraitItemKind::Method(hir::MethodSig {
-                ref decl, ..
-            }, ..), ..
-        }) = node {
-            decl.clone().and_then(|decl| {
-                Some((decl, ident, true))
-            })
-        } else if let Node::ImplItem(&hir::ImplItem {
-            ident, node: hir::ImplItemKind::Method(hir::MethodSig {
-                ref decl, ..
-            }, ..), ..
-        }) = node {
-            decl.clone().and_then(|decl| {
-                Some((decl, ident, false))
-            })
-        } else {
-            None
+            }),
+            Node::TraitItem(&hir::TraitItem {
+                ident, node: hir::TraitItemKind::Method(hir::MethodSig {
+                    ref decl, ..
+                }, ..), ..
+            }) => decl.clone().and_then(|decl| Some((decl, ident, true))),
+            Node::ImplItem(&hir::ImplItem {
+                ident, node: hir::ImplItemKind::Method(hir::MethodSig {
+                    ref decl, ..
+                }, ..), ..
+            }) => decl.clone().and_then(|decl| Some((decl, ident, false))),
+            _ => None,
         }
     }
 
diff --git a/src/test/ui/block-result/consider-removing-last-semi.stderr b/src/test/ui/block-result/consider-removing-last-semi.stderr
index 79e7a536cdc83..1bf17db21ac5a 100644
--- a/src/test/ui/block-result/consider-removing-last-semi.stderr
+++ b/src/test/ui/block-result/consider-removing-last-semi.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn f() -> String {  //~ ERROR mismatched types
    |    -      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     0u8;
 LL |     "bla".to_string();
    |                      - help: consider removing this semicolon
@@ -18,7 +18,7 @@ error[E0308]: mismatched types
 LL | fn g() -> String {  //~ ERROR mismatched types
    |    -      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     "this won't work".to_string();
 LL |     "removeme".to_string();
    |                           - help: consider removing this semicolon
diff --git a/src/test/ui/block-result/issue-11714.stderr b/src/test/ui/block-result/issue-11714.stderr
index 82253911316ad..2c13b28766943 100644
--- a/src/test/ui/block-result/issue-11714.stderr
+++ b/src/test/ui/block-result/issue-11714.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn blah() -> i32 { //~ ERROR mismatched types
    |    ----      ^^^ expected i32, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 ...
 LL |     ;
    |     - help: consider removing this semicolon
diff --git a/src/test/ui/block-result/issue-13428.stderr b/src/test/ui/block-result/issue-13428.stderr
index 8b8eb825377c4..91e926eb5a73b 100644
--- a/src/test/ui/block-result/issue-13428.stderr
+++ b/src/test/ui/block-result/issue-13428.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn foo() -> String {  //~ ERROR mismatched types
    |    ---      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 ...
 LL |     ;
    |     - help: consider removing this semicolon
@@ -18,7 +18,7 @@ error[E0308]: mismatched types
 LL | fn bar() -> String {  //~ ERROR mismatched types
    |    ---      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     "foobar".to_string()
 LL |     ;
    |     - help: consider removing this semicolon
diff --git a/src/test/ui/break-while-condition.stderr b/src/test/ui/break-while-condition.stderr
index 6709747b13767..3e81753a4105f 100644
--- a/src/test/ui/break-while-condition.stderr
+++ b/src/test/ui/break-while-condition.stderr
@@ -1,10 +1,11 @@
 error[E0308]: mismatched types
-  --> $DIR/break-while-condition.rs:3:11
+  --> $DIR/break-while-condition.rs:9:20
    |
-LL | fn main() {
-   |    ----   ^ expected !, found ()
-   |    |
-   |    this function's body doesn't return the expected type
+LL |           let _: ! = { //~ ERROR mismatched types
+   |  ____________________^
+LL | |             'a: while break 'a {};
+LL | |         };
+   | |_________^ expected !, found ()
    |
    = note: expected type `!`
               found type `()`
diff --git a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
index 9ace5b8ad3a8d..c8ec2f0545e6b 100644
--- a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
+++ b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn plus_one(x: i32) -> i32 { //~ ERROR mismatched types
    |    --------            ^^^ expected i32, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     x + 1;
    |          - help: consider removing this semicolon
    |
@@ -17,7 +17,7 @@ error[E0308]: mismatched types
 LL | fn foo() -> Result<u8, u64> { //~ ERROR mismatched types
    |    ---      ^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     Ok(1);
    |          - help: consider removing this semicolon
    |
diff --git a/src/test/ui/issues/issue-10536.stderr b/src/test/ui/issues/issue-10536.stderr
index 02008470e636f..d5caf777cd45e 100644
--- a/src/test/ui/issues/issue-10536.stderr
+++ b/src/test/ui/issues/issue-10536.stderr
@@ -17,12 +17,10 @@ LL |     assert!({one! two()});
    |              ^^^
 
 error[E0308]: mismatched types
-  --> $DIR/issue-10536.rs:11:15
+  --> $DIR/issue-10536.rs:14:13
    |
-LL | pub fn main() {
-   |        ----   ^ expected bool, found ()
-   |        |
-   |        this function's body doesn't return the expected type
+LL |     assert!({one! two()});
+   |             ^^^^^^^^^^^^ expected bool, found ()
    |
    = note: expected type `bool`
               found type `()`
diff --git a/src/test/ui/issues/issue-32323.stderr b/src/test/ui/issues/issue-32323.stderr
index bef3596103c2b..0339fdc55b9c8 100644
--- a/src/test/ui/issues/issue-32323.stderr
+++ b/src/test/ui/issues/issue-32323.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | pub fn f<'a, T: Tr<'a>>() -> <T as Tr<'a>>::Out {}
    |        -                     ^^^^^^^^^^^^^^^^^^ expected associated type, found ()
    |        |
-   |        this function's body doesn't return the expected type
+   |        this function's body doesn't return
    |
    = note: expected type `<T as Tr<'a>>::Out`
               found type `()`
diff --git a/src/test/ui/issues/issue-43162.stderr b/src/test/ui/issues/issue-43162.stderr
index 4d2b3549f8ed4..3fc5317830e48 100644
--- a/src/test/ui/issues/issue-43162.stderr
+++ b/src/test/ui/issues/issue-43162.stderr
@@ -16,7 +16,7 @@ error[E0308]: mismatched types
 LL | fn foo() -> bool {
    |    ---      ^^^^ expected bool, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     //~^ ERROR E0308
 LL |     break true; //~ ERROR E0268
    |               - help: consider removing this semicolon
diff --git a/src/test/ui/issues/issue-44023.stderr b/src/test/ui/issues/issue-44023.stderr
index 944098a644df2..f1962a86ee03a 100644
--- a/src/test/ui/issues/issue-44023.stderr
+++ b/src/test/ui/issues/issue-44023.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn საჭმელად_გემრიელი_სადილი ( ) -> isize { //~ ERROR mismatched types
    |    ------------------------        ^^^^^ expected isize, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/issues/issue-6458-4.stderr b/src/test/ui/issues/issue-6458-4.stderr
index f4cdceac1726a..c087292e978c2 100644
--- a/src/test/ui/issues/issue-6458-4.stderr
+++ b/src/test/ui/issues/issue-6458-4.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn foo(b: bool) -> Result<bool,String> { //~ ERROR mismatched types
    |    ---             ^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     Err("bar".to_string());
    |                           - help: consider removing this semicolon
    |
diff --git a/src/test/ui/liveness/liveness-closure-require-ret.stderr b/src/test/ui/liveness/liveness-closure-require-ret.stderr
index d7992704c50e8..3133efdedd762 100644
--- a/src/test/ui/liveness/liveness-closure-require-ret.stderr
+++ b/src/test/ui/liveness/liveness-closure-require-ret.stderr
@@ -1,10 +1,8 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-closure-require-ret.rs:2:11
+  --> $DIR/liveness-closure-require-ret.rs:2:37
    |
 LL | fn main() { println!("{}", force(|| {})); } //~ ERROR mismatched types
-   |    ----   ^ expected isize, found ()
-   |    |
-   |    this function's body doesn't return the expected type
+   |                                     ^^ expected isize, found ()
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-forgot-ret.stderr b/src/test/ui/liveness/liveness-forgot-ret.stderr
index 578890f5e625f..bbcbbdbe8dd5b 100644
--- a/src/test/ui/liveness/liveness-forgot-ret.stderr
+++ b/src/test/ui/liveness/liveness-forgot-ret.stderr
@@ -2,10 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/liveness-forgot-ret.rs:3:19
    |
 LL | fn f(a: isize) -> isize { if god_exists(a) { return 5; }; }
-   |    -              ^^^^^                             - expected because of this statement
-   |    |              |
-   |    |              expected isize, found ()
-   |    this function's body doesn't return the expected type
+   |    -              ^^^^^ expected isize, found ()    - expected because of this statement
+   |    |
+   |    this function's body doesn't return
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-issue-2163.stderr b/src/test/ui/liveness/liveness-issue-2163.stderr
index a8a5684207608..e91994d9a2299 100644
--- a/src/test/ui/liveness/liveness-issue-2163.stderr
+++ b/src/test/ui/liveness/liveness-issue-2163.stderr
@@ -1,10 +1,11 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-issue-2163.rs:3:11
+  --> $DIR/liveness-issue-2163.rs:5:30
    |
-LL | fn main() {
-   |    ----   ^ expected bool, found ()
-   |    |
-   |    this function's body doesn't return the expected type
+LL |       a.iter().all(|_| -> bool {
+   |  ______________________________^
+LL | |         //~^ ERROR mismatched types
+LL | |     });
+   | |_____^ expected bool, found ()
    |
    = note: expected type `bool`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-missing-ret2.stderr b/src/test/ui/liveness/liveness-missing-ret2.stderr
index 201b3ee6861a1..58d0249ee3b24 100644
--- a/src/test/ui/liveness/liveness-missing-ret2.stderr
+++ b/src/test/ui/liveness/liveness-missing-ret2.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn f() -> isize { //~ ERROR mismatched types
    |    -      ^^^^^ expected isize, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
    |
    = note: expected type `isize`
               found type `()`
diff --git a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
index 2ee77f30a6608..c6d166d8b31a0 100644
--- a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
+++ b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
@@ -5,7 +5,7 @@ LL | macro_rules! test { () => { fn foo() -> i32 { 1; } } }
    |                                ---      ^^^    - help: consider removing this semicolon
    |                                |        |
    |                                |        expected i32, found ()
-   |                                this function's body doesn't return the expected type
+   |                                this function's body doesn't return
 ...
 LL |     test!();
    |     -------- in this macro invocation
@@ -19,7 +19,7 @@ error[E0308]: mismatched types
 LL | fn no_return() -> i32 {} //~ ERROR mismatched types
    |    ---------      ^^^ expected i32, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
    |
    = note: expected type `i32`
               found type `()`
@@ -30,7 +30,7 @@ error[E0308]: mismatched types
 LL | fn bar(x: u32) -> u32 { //~ ERROR mismatched types
    |    ---            ^^^ expected u32, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
 LL |     x * 2;
    |          - help: consider removing this semicolon
    |
@@ -43,7 +43,7 @@ error[E0308]: mismatched types
 LL | fn baz(x: u64) -> u32 { //~ ERROR mismatched types
    |    ---            ^^^ expected u32, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
    |
    = note: expected type `u32`
               found type `()`
diff --git a/src/test/ui/missing/missing-return.stderr b/src/test/ui/missing/missing-return.stderr
index 9e6ffd97312f0..42466e2fc6574 100644
--- a/src/test/ui/missing/missing-return.stderr
+++ b/src/test/ui/missing/missing-return.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn f() -> isize { }
    |    -      ^^^^^ expected isize, found ()
    |    |
-   |    this function's body doesn't return the expected type
+   |    this function's body doesn't return
    |
    = note: expected type `isize`
               found type `()`

From 211365d68c8eb5515cb658c4c240c73c122d2c5e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 4 Jan 2019 11:17:23 -0800
Subject: [PATCH 4/4] review comments

---
 src/librustc_typeck/check/mod.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 9492b1a2341dc..fa6f3843f7c52 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4859,13 +4859,13 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         None
     }
 
-    /// Given a function block's `NodeId`, return its `FnDecl` , `None` otherwise.
+    /// Given a function block's `NodeId`, return its `FnDecl` if it exists, or `None` otherwise.
     fn get_parent_fn_decl(&self, blk_id: ast::NodeId) -> Option<(hir::FnDecl, ast::Ident)> {
         let parent = self.tcx.hir().get(self.tcx.hir().get_parent(blk_id));
-        self.get_node_fn_decl(parent).map(|(fn_decl, ident , _)| (fn_decl, ident))
+        self.get_node_fn_decl(parent).map(|(fn_decl, ident, _)| (fn_decl, ident))
     }
 
-    /// Given a function `Node`, return its `FnDecl` , `None` otherwise.
+    /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise.
     fn get_node_fn_decl(&self, node: Node) -> Option<(hir::FnDecl, ast::Ident, bool)> {
         match node {
             Node::Item(&hir::Item {