Rollup merge of rust-lang#100652 - compiler-errors:no-defer-sized-checks, r=TaKO8Ki

Remove deferred sized checks (make them eager)

Improves diagnostics spans... this doesn't seem to be the case anymore:

```rust
// Some additional `Sized` obligations badly affect type inference.
// These obligations are added in a later stage of typeck.
pub(super) deferred_sized_obligations:
        RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
```

Author: matthiaskrgr

compiler/rustc_typeck/src/check/expr.rs

@@ -561,16 +561,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // We just want to check sizedness, so instead of introducing
                     // placeholder lifetimes with probing, we just replace higher lifetimes
                     // with fresh vars.
-                    let span = args.get(i).map(|a| a.span).unwrap_or(expr.span);
+                    let arg_span = args.get(i).map(|a| a.span);
+                    let span = arg_span.unwrap_or(expr.span);
                     let input = self.replace_bound_vars_with_fresh_vars(
                         span,
                         infer::LateBoundRegionConversionTime::FnCall,
                         fn_sig.input(i),
                     );
-                    self.require_type_is_sized_deferred(
-                        input,
+                    self.require_type_is_sized(
+                        self.normalize_associated_types_in(span, input),
                         span,
-                        traits::SizedArgumentType(None),
+                        traits::SizedArgumentType(arg_span),
                     );
                 }
             }
@@ -585,7 +586,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 infer::LateBoundRegionConversionTime::FnCall,
                 fn_sig.output(),
             );
-            self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType);
+            self.require_type_is_sized(
+                self.normalize_associated_types_in(expr.span, output),
+                expr.span,
+                traits::SizedReturnType,
+            );
         }
 
         // We always require that the type provided as the value for

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -442,17 +442,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    pub fn require_type_is_sized_deferred(
-        &self,
-        ty: Ty<'tcx>,
-        span: Span,
-        code: traits::ObligationCauseCode<'tcx>,
-    ) {
-        if !ty.references_error() {
-            self.deferred_sized_obligations.borrow_mut().push((ty, span, code));
-        }
-    }
-
     pub fn register_bound(
         &self,
         ty: Ty<'tcx>,

compiler/rustc_typeck/src/check/inherited.rs

@@ -35,11 +35,6 @@ pub struct Inherited<'a, 'tcx> {
 
     pub(super) fulfillment_cx: RefCell<Box<dyn TraitEngine<'tcx>>>,
 
-    // Some additional `Sized` obligations badly affect type inference.
-    // These obligations are added in a later stage of typeck.
-    pub(super) deferred_sized_obligations:
-        RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
-
     // When we process a call like `c()` where `c` is a closure type,
     // we may not have decided yet whether `c` is a `Fn`, `FnMut`, or
     // `FnOnce` closure. In that case, we defer full resolution of the
@@ -117,7 +112,6 @@ impl<'a, 'tcx> Inherited<'a, 'tcx> {
             infcx,
             fulfillment_cx: RefCell::new(<dyn TraitEngine<'_>>::new(tcx)),
             locals: RefCell::new(Default::default()),
-            deferred_sized_obligations: RefCell::new(Vec::new()),
             deferred_call_resolutions: RefCell::new(Default::default()),
             deferred_cast_checks: RefCell::new(Vec::new()),
             deferred_transmute_checks: RefCell::new(Vec::new()),

compiler/rustc_typeck/src/check/mod.rs

@@ -467,11 +467,6 @@ fn typeck_with_fallback<'tcx>(
         fcx.resolve_rvalue_scopes(def_id.to_def_id());
         fcx.resolve_generator_interiors(def_id.to_def_id());
 
-        for (ty, span, code) in fcx.deferred_sized_obligations.borrow_mut().drain(..) {
-            let ty = fcx.normalize_ty(span, ty);
-            fcx.require_type_is_sized(ty, span, code);
-        }
-
         fcx.select_all_obligations_or_error();
 
         if !fcx.infcx.is_tainted_by_errors() {

src/test/incremental/const-generics/hash-tyvid-regression-1.rs

@@ -9,7 +9,6 @@ where
     use std::convert::TryFrom;
     <[T; N.get()]>::try_from(())
     //~^ error: the trait bound
-    //~| error: the trait bound
     //~| error: mismatched types
 }
 

src/test/ui/associated-types/associated-types-path-2.stderr

@@ -33,7 +33,9 @@ error[E0277]: the trait bound `u32: Foo` is not satisfied
   --> $DIR/associated-types-path-2.rs:29:14
    |
 LL |     f1(2u32, 4u32);
-   |              ^^^^ the trait `Foo` is not implemented for `u32`
+   |     --       ^^^^ the trait `Foo` is not implemented for `u32`
+   |     |
+   |     required by a bound introduced by this call
    |
    = help: the trait `Foo` is implemented for `i32`
 

src/test/ui/feature-gates/feature-gate-unsized_fn_params.stderr

@@ -15,11 +15,16 @@ error[E0277]: the size for values of type `(dyn Foo + 'static)` cannot be known
   --> $DIR/feature-gate-unsized_fn_params.rs:24:9
    |
 LL |     foo(*x);
-   |         ^^ doesn't have a size known at compile-time
+   |     --- ^^ doesn't have a size known at compile-time
+   |     |
+   |     required by a bound introduced by this call
    |
    = help: the trait `Sized` is not implemented for `(dyn Foo + 'static)`
-   = note: all function arguments must have a statically known size
    = help: unsized fn params are gated as an unstable feature
+help: function arguments must have a statically known size, borrowed types always have a known size
+   |
+LL |     foo(&*x);
+   |         +
 
 error: aborting due to 2 previous errors
 

src/test/ui/iterators/issue-28098.rs

@@ -1,7 +1,6 @@
 fn main() {
     let _ = Iterator::next(&mut ());
     //~^ ERROR `()` is not an iterator
-    //~| ERROR `()` is not an iterator
 
     for _ in false {}
     //~^ ERROR `bool` is not an iterator
@@ -17,7 +16,6 @@ pub fn other() {
 
     let _ = Iterator::next(&mut ());
     //~^ ERROR `()` is not an iterator
-    //~| ERROR `()` is not an iterator
 
     let _ = Iterator::next(&mut ());
     //~^ ERROR `()` is not an iterator

src/test/ui/iterators/issue-28098.stderr

@@ -9,7 +9,7 @@ LL |     let _ = Iterator::next(&mut ());
    = help: the trait `Iterator` is not implemented for `()`
 
 error[E0277]: `bool` is not an iterator
-  --> $DIR/issue-28098.rs:6:14
+  --> $DIR/issue-28098.rs:5:14
    |
 LL |     for _ in false {}
    |              ^^^^^ `bool` is not an iterator
@@ -18,7 +18,7 @@ LL |     for _ in false {}
    = note: required because of the requirements on the impl of `IntoIterator` for `bool`
 
 error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:9:28
+  --> $DIR/issue-28098.rs:8:28
    |
 LL |     let _ = Iterator::next(&mut ());
    |             -------------- ^^^^^^^ `()` is not an iterator
@@ -28,15 +28,7 @@ LL |     let _ = Iterator::next(&mut ());
    = help: the trait `Iterator` is not implemented for `()`
 
 error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:2:13
-   |
-LL |     let _ = Iterator::next(&mut ());
-   |             ^^^^^^^^^^^^^^ `()` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `()`
-
-error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:18:28
+  --> $DIR/issue-28098.rs:17:28
    |
 LL |     let _ = Iterator::next(&mut ());
    |             -------------- ^^^^^^^ `()` is not an iterator
@@ -46,7 +38,7 @@ LL |     let _ = Iterator::next(&mut ());
    = help: the trait `Iterator` is not implemented for `()`
 
 error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:22:28
+  --> $DIR/issue-28098.rs:20:28
    |
 LL |     let _ = Iterator::next(&mut ());
    |             -------------- ^^^^^^^ `()` is not an iterator
@@ -56,22 +48,14 @@ LL |     let _ = Iterator::next(&mut ());
    = help: the trait `Iterator` is not implemented for `()`
 
 error[E0277]: `bool` is not an iterator
-  --> $DIR/issue-28098.rs:25:14
+  --> $DIR/issue-28098.rs:23:14
    |
 LL |     for _ in false {}
    |              ^^^^^ `bool` is not an iterator
    |
    = help: the trait `Iterator` is not implemented for `bool`
    = note: required because of the requirements on the impl of `IntoIterator` for `bool`
 
-error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:18:13
-   |
-LL |     let _ = Iterator::next(&mut ());
-   |             ^^^^^^^^^^^^^^ `()` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `()`
-
-error: aborting due to 8 previous errors
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

src/test/ui/on-unimplemented/multiple-impls.rs

@@ -32,11 +32,8 @@ impl Index<Bar<usize>> for [i32] {
 fn main() {
     Index::index(&[] as &[i32], 2u32);
     //~^ ERROR E0277
-    //~| ERROR E0277
     Index::index(&[] as &[i32], Foo(2u32));
     //~^ ERROR E0277
-    //~| ERROR E0277
     Index::index(&[] as &[i32], Bar(2u32));
     //~^ ERROR E0277
-    //~| ERROR E0277
 }