More accurately point to where default return type should go

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1189,7 +1189,7 @@ fn report_trait_method_mismatch<'tcx>(
                     let ap = Applicability::MachineApplicable;
                     match sig.decl.output {
                         hir::FnRetTy::DefaultReturn(sp) => {
-                            let sugg = format!("-> {} ", trait_sig.output());
+                            let sugg = format!(" -> {}", trait_sig.output());
                             diag.span_suggestion_verbose(sp, msg, sugg, ap);
                         }
                         hir::FnRetTy::Return(hir_ty) => {

compiler/rustc_hir_typeck/src/check.rs

@@ -113,7 +113,11 @@ pub(super) fn check_fn<'a, 'tcx>(
 
     fcx.typeck_results.borrow_mut().liberated_fn_sigs_mut().insert(fn_id, fn_sig);
 
-    fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType);
+    let return_or_body_span = match decl.output {
+        hir::FnRetTy::DefaultReturn(_) => body.value.span,
+        hir::FnRetTy::Return(ty) => ty.span,
+    };
+    fcx.require_type_is_sized(declared_ret_ty, return_or_body_span, traits::SizedReturnType);
     fcx.check_return_expr(&body.value, false);
 
     // We insert the deferred_generator_interiors entry after visiting the body.

compiler/rustc_hir_typeck/src/errors.rs

@@ -110,7 +110,7 @@ pub struct AddressOfTemporaryTaken {
 pub enum AddReturnTypeSuggestion {
     #[suggestion(
         hir_typeck_add_return_type_add,
-        code = "-> {found} ",
+        code = " -> {found}",
         applicability = "machine-applicable"
     )]
     Add {
@@ -120,7 +120,7 @@ pub enum AddReturnTypeSuggestion {
     },
     #[suggestion(
         hir_typeck_add_return_type_missing_here,
-        code = "-> _ ",
+        code = " -> _",
         applicability = "has-placeholders"
     )]
     MissingHere {

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -782,8 +782,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
             }
             hir::FnRetTy::Return(hir_ty) => {
-                let span = hir_ty.span;
-
                 if let hir::TyKind::OpaqueDef(item_id, ..) = hir_ty.kind
                     && let hir::Node::Item(hir::Item {
                         kind: hir::ItemKind::OpaqueTy(op_ty),
@@ -799,28 +797,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     debug!(?found);
                     if found.is_suggestable(self.tcx, false) {
                         if term.span.is_empty() {
-                            err.subdiagnostic(errors::AddReturnTypeSuggestion::Add { span, found: found.to_string() });
+                            err.subdiagnostic(errors::AddReturnTypeSuggestion::Add { span: term.span, found: found.to_string() });
                             return true;
                         } else {
-                            err.subdiagnostic(errors::ExpectedReturnTypeLabel::Other { span, expected });
+                            err.subdiagnostic(errors::ExpectedReturnTypeLabel::Other { span: term.span, expected });
                         }
                     }
-                }
-
-                // Only point to return type if the expected type is the return type, as if they
-                // are not, the expectation must have been caused by something else.
-                debug!("return type {:?}", hir_ty);
-                let ty = self.astconv().ast_ty_to_ty(hir_ty);
-                debug!("return type {:?}", ty);
-                debug!("expected type {:?}", expected);
-                let bound_vars = self.tcx.late_bound_vars(hir_ty.hir_id.owner.into());
-                let ty = Binder::bind_with_vars(ty, bound_vars);
-                let ty = self.normalize(span, ty);
-                let ty = self.tcx.erase_late_bound_regions(ty);
-                if self.can_coerce(expected, ty) {
-                    err.subdiagnostic(errors::ExpectedReturnTypeLabel::Other { span, expected });
-                    self.try_suggest_return_impl_trait(err, expected, ty, fn_id);
-                    return true;
+                } else {
+                    // Only point to return type if the expected type is the return type, as if they
+                    // are not, the expectation must have been caused by something else.
+                    debug!("return type {:?}", hir_ty);
+                    let ty = self.astconv().ast_ty_to_ty(hir_ty);
+                    debug!("return type {:?}", ty);
+                    debug!("expected type {:?}", expected);
+                    let bound_vars = self.tcx.late_bound_vars(hir_ty.hir_id.owner.into());
+                    let ty = Binder::bind_with_vars(ty, bound_vars);
+                    let ty = self.normalize(hir_ty.span, ty);
+                    let ty = self.tcx.erase_late_bound_regions(ty);
+                    if self.can_coerce(expected, ty) {
+                        err.subdiagnostic(errors::ExpectedReturnTypeLabel::Other { span: hir_ty.span, expected });
+                        self.try_suggest_return_impl_trait(err, expected, ty, fn_id);
+                        return true;
+                    }
                 }
             }
             _ => {}

compiler/rustc_infer/src/errors/mod.rs

@@ -194,13 +194,13 @@ impl<'a> SourceKindMultiSuggestion<'a> {
         data: &'a FnRetTy<'a>,
         should_wrap_expr: Option<Span>,
     ) -> Self {
-        let (arrow, post) = match data {
-            FnRetTy::DefaultReturn(_) => ("-> ", " "),
-            _ => ("", ""),
+        let arrow = match data {
+            FnRetTy::DefaultReturn(_) => " -> ",
+            _ => "",
         };
         let (start_span, start_span_code, end_span) = match should_wrap_expr {
-            Some(end_span) => (data.span(), format!("{arrow}{ty_info}{post}{{ "), Some(end_span)),
-            None => (data.span(), format!("{arrow}{ty_info}{post}"), None),
+            Some(end_span) => (data.span(), format!("{arrow}{ty_info} {{"), Some(end_span)),
+            None => (data.span(), format!("{arrow}{ty_info}"), None),
         };
         Self::ClosureReturn { start_span, start_span_code, end_span }
     }

compiler/rustc_parse/src/parser/ty.rs

@@ -247,7 +247,7 @@ impl<'a> Parser<'a> {
             )?;
             FnRetTy::Ty(ty)
         } else {
-            FnRetTy::Default(self.token.span.shrink_to_lo())
+            FnRetTy::Default(self.prev_token.span.shrink_to_hi())
         })
     }
 

src/tools/clippy/clippy_lints/src/methods/unnecessary_literal_unwrap.rs

@@ -102,14 +102,10 @@ pub(super) fn check(
             ]),
             ("None", "unwrap_or_else", _) => match args[0].kind {
                 hir::ExprKind::Closure(hir::Closure {
-                    fn_decl:
-                        hir::FnDecl {
-                            output: hir::FnRetTy::DefaultReturn(span) | hir::FnRetTy::Return(hir::Ty { span, .. }),
-                            ..
-                        },
+                    body,
                     ..
                 }) => Some(vec![
-                    (expr.span.with_hi(span.hi()), String::new()),
+                    (expr.span.with_hi(cx.tcx.hir().body(*body).value.span.lo()), String::new()),
                     (expr.span.with_lo(args[0].span.hi()), String::new()),
                 ]),
                 _ => None,

src/tools/clippy/tests/ui-toml/too_many_arguments/too_many_arguments.stderr

@@ -2,7 +2,7 @@ error: this function has too many arguments (11/10)
   --> $DIR/too_many_arguments.rs:4:1
    |
 LL | fn too_many(p1: u8, p2: u8, p3: u8, p4: u8, p5: u8, p6: u8, p7: u8, p8: u8, p9: u8, p10: u8, p11: u8) {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::too-many-arguments` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::too_many_arguments)]`

src/tools/clippy/tests/ui/functions.stderr

@@ -2,7 +2,7 @@ error: this function has too many arguments (8/7)
   --> $DIR/functions.rs:8:1
    |
 LL | fn bad(_one: u32, _two: u32, _three: &str, _four: bool, _five: f32, _six: f32, _seven: bool, _eight: ()) {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::too-many-arguments` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::too_many_arguments)]`
@@ -17,7 +17,7 @@ LL | |     two: u32,
 ...  |
 LL | |     eight: ()
 LL | | ) {
-   | |__^
+   | |_^
 
 error: this function has too many arguments (8/7)
   --> $DIR/functions.rs:48:5
@@ -29,7 +29,7 @@ error: this function has too many arguments (8/7)
   --> $DIR/functions.rs:58:5
    |
 LL |     fn bad_method(_one: u32, _two: u32, _three: &str, _four: bool, _five: f32, _six: f32, _seven: bool, _eight: ()) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this public function might dereference a raw pointer but is not marked `unsafe`
   --> $DIR/functions.rs:68:34

src/tools/clippy/tests/ui/must_use_unit.stderr

@@ -4,7 +4,7 @@ error: this unit-returning function has a `#[must_use]` attribute
 LL | #[must_use]
    | ----------- help: remove the attribute
 LL | pub fn must_use_default() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::must-use-unit` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::must_use_unit)]`
@@ -23,7 +23,7 @@ error: this unit-returning function has a `#[must_use]` attribute
 LL | #[must_use = "With note"]
    | ------------------------- help: remove the attribute
 LL | pub fn must_use_with_note() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors
 

src/tools/clippy/tests/ui/unnecessary_literal_unwrap.fixed

@@ -23,15 +23,15 @@ fn unwrap_option_none() {
     let _val: u16 = 234;
     let _val: u16 = 234;
     let _val: u16 = { 234 };
-    let _val: u16 =  { 234 };
+    let _val: u16 = { 234 };
 
     panic!();
     panic!("this always happens");
     String::default();
     234;
     234;
     { 234 };
-     { 234 };
+    { 234 };
 }
 
 fn unwrap_result_ok() {

src/tools/clippy/tests/ui/unnecessary_literal_unwrap.stderr

@@ -116,7 +116,7 @@ LL |     let _val: u16 = None.unwrap_or_else(|| -> u16 { 234 });
 help: remove the `None` and `unwrap_or_else()`
    |
 LL -     let _val: u16 = None.unwrap_or_else(|| -> u16 { 234 });
-LL +     let _val: u16 =  { 234 };
+LL +     let _val: u16 = { 234 };
    |
 
 error: used `unwrap()` on `None` value
@@ -187,7 +187,7 @@ LL |     None::<u16>.unwrap_or_else(|| -> u16 { 234 });
 help: remove the `None` and `unwrap_or_else()`
    |
 LL -     None::<u16>.unwrap_or_else(|| -> u16 { 234 });
-LL +      { 234 };
+LL +     { 234 };
    |
 
 error: used `unwrap()` on `Ok` value

src/tools/rustfmt/src/items.rs

@@ -2599,7 +2599,8 @@ fn rewrite_fn_base(
     if where_clause_str.is_empty() {
         if let ast::FnRetTy::Default(ret_span) = fd.output {
             match recover_missing_comment_in_span(
-                mk_sp(params_span.hi(), ret_span.hi()),
+                // from after the closing paren to right before block or semicolon
+                mk_sp(ret_span.lo(), span.hi()),
                 shape,
                 context,
                 last_line_width(&result),

tests/ui/associated-type-bounds/issue-71443-1.stderr

@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-71443-1.rs:6:5
    |
 LL | fn hello<F: for<'a> Iterator<Item: 'a>>() {
-   |                                           - help: try adding a return type: `-> Incorrect`
+   |                                          - help: try adding a return type: `-> Incorrect`
 LL |     Incorrect
    |     ^^^^^^^^^ expected `()`, found `Incorrect`
 

tests/ui/block-result/block-must-not-have-result-res.stderr

@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/block-must-not-have-result-res.rs:5:9
    |
 LL |     fn drop(&mut self) {
-   |                        - expected `()` because of default return type
+   |                       - expected `()` because of default return type
 LL |         true
    |         ^^^^ expected `()`, found `bool`
 

tests/ui/block-result/issue-20862.stderr

@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-20862.rs:2:5
    |
 LL | fn foo(x: i32) {
-   |                - help: a return type might be missing here: `-> _`
+   |               - help: a return type might be missing here: `-> _`
 LL |     |y| x + y
    |     ^^^^^^^^^ expected `()`, found closure
    |

tests/ui/block-result/issue-22645.stderr

@@ -17,7 +17,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-22645.rs:15:3
    |
 LL | fn main() {
-   |           - expected `()` because of default return type
+   |          - expected `()` because of default return type
 LL |   let b = Bob + 3.5;
 LL |   b + 3
    |   ^^^^^ expected `()`, found `Bob`

tests/ui/block-result/issue-5500.stderr

@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-5500.rs:2:5
    |
 LL | fn main() {
-   |           - expected `()` because of default return type
+   |          - expected `()` because of default return type
 LL |     &panic!()
    |     ^^^^^^^^^ expected `()`, found `&_`
    |

tests/ui/closures/add_semicolon_non_block_closure.stderr

@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/add_semicolon_non_block_closure.rs:8:12
    |
 LL | fn main() {
-   |           - expected `()` because of default return type
+   |          - expected `()` because of default return type
 LL |     foo(|| bar())
    |            ^^^^^ expected `()`, found `i32`
    |

tests/ui/closures/binder/implicit-return.stderr

@@ -1,8 +1,8 @@
 error: implicit types in closure signatures are forbidden when `for<...>` is present
-  --> $DIR/implicit-return.rs:4:34
+  --> $DIR/implicit-return.rs:4:33
    |
 LL |     let _f = for<'a> |_: &'a ()| {};
-   |              -------             ^
+   |              -------            ^
    |              |
    |              `for<...>` is here
 

tests/ui/closures/binder/implicit-stuff.stderr

@@ -41,10 +41,10 @@ LL |     let _ = for<'a> |x: &'a ()| -> &() { x };
    |                                    ^ explicit lifetime name needed here
 
 error: implicit types in closure signatures are forbidden when `for<...>` is present
-  --> $DIR/implicit-stuff.rs:5:22
+  --> $DIR/implicit-stuff.rs:5:21
    |
 LL |     let _ = for<> || {};
-   |             -----    ^
+   |             -----   ^
    |             |
    |             `for<...>` is here
 

tests/ui/codemap_tests/tab.stderr

@@ -8,7 +8,7 @@ error[E0308]: mismatched types
   --> $DIR/tab.rs:8:2
    |
 LL | fn foo() {
-   |          - help: try adding a return type: `-> &'static str`
+   |         - help: try adding a return type: `-> &'static str`
 LL |     "bar            boo"
    |     ^^^^^^^^^^^^^^^^^^^^ expected `()`, found `&str`
 

tests/ui/compare-method/bad-self-type.stderr

@@ -28,10 +28,10 @@ LL |     fn foo(self);
               found signature `fn(Box<MyFuture>)`
 
 error[E0053]: method `bar` has an incompatible type for trait
-  --> $DIR/bad-self-type.rs:24:18
+  --> $DIR/bad-self-type.rs:24:17
    |
 LL |     fn bar(self) {}
-   |                  ^ expected `Option<()>`, found `()`
+   |                 ^ expected `Option<()>`, found `()`
    |
 note: type in trait
   --> $DIR/bad-self-type.rs:18:21

tests/ui/impl-trait/in-trait/refine.stderr

@@ -30,8 +30,8 @@ LL |     fn bar() {}
    = note: add `#[allow(refining_impl_trait)]` if it is intended for this to be part of the public API of this crate
 help: replace the return type so that it matches the trait
    |
-LL |     fn bar() -> impl Sized {}
-   |              +++++++++++++
+LL |     fn bar()-> impl Sized  {}
+   |             +++++++++++++
 
 error: impl trait in impl method signature does not match trait method signature
   --> $DIR/refine.rs:22:17

tests/ui/issues/issue-66667-function-cmp-cycle.stderr

@@ -19,7 +19,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-66667-function-cmp-cycle.rs:2:5
    |
 LL | fn first() {
-   |            - help: try adding a return type: `-> bool`
+   |           - help: try adding a return type: `-> bool`
 LL |     second == 1
    |     ^^^^^^^^^^^ expected `()`, found `bool`
 
@@ -44,7 +44,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-66667-function-cmp-cycle.rs:8:5
    |
 LL | fn second() {
-   |             - help: try adding a return type: `-> bool`
+   |            - help: try adding a return type: `-> bool`
 LL |     first == 1
    |     ^^^^^^^^^^ expected `()`, found `bool`
 
@@ -69,7 +69,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-66667-function-cmp-cycle.rs:14:5
    |
 LL | fn bar() {
-   |          - help: try adding a return type: `-> bool`
+   |         - help: try adding a return type: `-> bool`
 LL |     bar == 1
    |     ^^^^^^^^ expected `()`, found `bool`
 

tests/ui/lang-items/start_lang_item_args.missing_ret.stderr

@@ -1,8 +1,8 @@
 error[E0308]: lang item `start` function has wrong type
-  --> $DIR/start_lang_item_args.rs:29:84
+  --> $DIR/start_lang_item_args.rs:29:83
    |
 LL | fn start<T>(_main: fn() -> T, _argc: isize, _argv: *const *const u8, _sigpipe: u8) {}
-   |                                                                                    ^ expected `isize`, found `()`
+   |                                                                                   ^ expected `isize`, found `()`
    |
    = note: expected signature `fn(fn() -> _, _, _, _) -> isize`
               found signature `fn(fn() -> _, _, _, _)`

tests/ui/loops/loop-break-value.stderr

@@ -319,7 +319,7 @@ error[E0308]: mismatched types
   --> $DIR/loop-break-value.rs:159:15
    |
 LL | fn main() {
-   |           - expected `()` because of this return type
+   |          - expected `()` because of this return type
 ...
 LL |     loop { // point at the return type
    |     ---- this loop is expected to be of type `()`