review comment: review wording or missing return error

Author: estebank

src/librustc_typeck/check/mod.rs

@@ -3711,7 +3711,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         if let Some(fn_span) = fn_span {
                             err.span_label(
                                 fn_span,
-                                "this function's body doesn't `return` a value",
+                                "this function implicitly returns `()` as its body has no tail \
+                                 or `return` expression",
                             );
                         }
                     }, false);

src/test/ui/block-result/consider-removing-last-semi.stderr

@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn f() -> String {
    |    -      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 LL |     0u8;
 LL |     "bla".to_string();
    |                      - help: consider removing this semicolon
@@ -18,7 +18,7 @@ error[E0308]: mismatched types
 LL | fn g() -> String {
    |    -      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 LL |     "this won't work".to_string();
 LL |     "removeme".to_string();
    |                           - help: consider removing this semicolon

src/test/ui/block-result/issue-11714.stderr

@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn blah() -> i32 {
    |    ----      ^^^ expected i32, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 ...
 LL |     ;
    |     - help: consider removing this semicolon

src/test/ui/block-result/issue-13428.stderr

@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn foo() -> String {
    |    ---      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 ...
 LL |     ;
    |     - help: consider removing this semicolon
@@ -18,7 +18,7 @@ error[E0308]: mismatched types
 LL | fn bar() -> String {
    |    ---      ^^^^^^ expected struct `std::string::String`, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 LL |     "foobar".to_string()
 LL |     ;
    |     - help: consider removing this semicolon

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 {
    |    --------            ^^^ expected i32, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 LL |     x + 1;
    |          - help: consider removing this semicolon
    |
@@ -17,7 +17,7 @@ error[E0308]: mismatched types
 LL | fn foo() -> Result<u8, u64> {
    |    ---      ^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 LL |     Ok(1);
    |          - help: consider removing this semicolon
    |

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` a value
+   |        this function implicitly returns `()` as its body has no tail or `return` expression
    |
    = note: expected type `<T as Tr<'a>>::Out`
               found type `()`

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` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 LL |
 LL |     break true;
    |               - help: consider removing this semicolon

src/test/ui/issues/issue-44023.stderr

@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn საჭმელად_გემრიელი_სადილი ( ) -> isize {
    |    ------------------------        ^^^^^ expected isize, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
    |
    = note: expected type `isize`
               found type `()`

src/test/ui/issues/issue-6458-4.stderr

@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn foo(b: bool) -> Result<bool,String> {
    |    ---             ^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
 LL |     Err("bar".to_string());
    |                           - help: consider removing this semicolon
    |

src/test/ui/liveness/liveness-forgot-ret.stderr

@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn f(a: isize) -> isize { if god_exists(a) { return 5; }; }
    |    -              ^^^^^ expected isize, found ()
    |    |
-   |    this function's body doesn't `return` a value
+   |    this function implicitly returns `()` as its body has no tail or `return` expression
    |
    = note: expected type `isize`
               found type `()`