Revert "Remove deferred sized checks"

compiler/rustc_typeck/src/check/expr.rs

@@ -561,17 +561,16 @@ 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 arg_span = args.get(i).map(|a| a.span);
-                    let span = arg_span.unwrap_or(expr.span);
+                    let span = args.get(i).map(|a| a.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(
-                        self.normalize_associated_types_in(span, input),
+                    self.require_type_is_sized_deferred(
+                        input,
                         span,
-                        traits::SizedArgumentType(arg_span),
+                        traits::SizedArgumentType(None),
                     );
                 }
             }
@@ -586,11 +585,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 infer::LateBoundRegionConversionTime::FnCall,
                 fn_sig.output(),
             );
-            self.require_type_is_sized(
-                self.normalize_associated_types_in(expr.span, output),
-                expr.span,
-                traits::SizedReturnType,
-            );
+            self.require_type_is_sized_deferred(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

@@ -442,6 +442,17 @@ 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

@@ -35,6 +35,12 @@ 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.
+    // Removing these may also cause additional complications, see #101066.
+    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
@@ -112,6 +118,7 @@ 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

@@ -466,6 +466,11 @@ 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

@@ -9,6 +9,7 @@ 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.rs

@@ -29,12 +29,14 @@ pub fn f1_uint_uint() {
     f1(2u32, 4u32);
     //~^ ERROR `u32: Foo` is not satisfied
     //~| ERROR `u32: Foo` is not satisfied
+    //~| ERROR `u32: Foo` is not satisfied
 }
 
 pub fn f1_uint_int() {
     f1(2u32, 4i32);
     //~^ ERROR `u32: Foo` is not satisfied
     //~| ERROR `u32: Foo` is not satisfied
+    //~| ERROR `u32: Foo` is not satisfied
 }
 
 pub fn f2_int() {

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

@@ -31,6 +31,14 @@ note: required by a bound in `f1`
 LL | pub fn f1<T: Foo>(a: T, x: T::A) {}
    |              ^^^ required by this bound in `f1`
 
+error[E0277]: the trait bound `u32: Foo` is not satisfied
+  --> $DIR/associated-types-path-2.rs:29:5
+   |
+LL |     f1(2u32, 4u32);
+   |     ^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `u32`
+   |
+   = help: the trait `Foo` is implemented for `i32`
+
 error[E0277]: the trait bound `u32: Foo` is not satisfied
   --> $DIR/associated-types-path-2.rs:29:14
    |
@@ -40,7 +48,7 @@ LL |     f1(2u32, 4u32);
    = help: the trait `Foo` is implemented for `i32`
 
 error[E0277]: the trait bound `u32: Foo` is not satisfied
-  --> $DIR/associated-types-path-2.rs:35:8
+  --> $DIR/associated-types-path-2.rs:36:8
    |
 LL |     f1(2u32, 4i32);
    |     -- ^^^^ the trait `Foo` is not implemented for `u32`
@@ -55,15 +63,23 @@ LL | pub fn f1<T: Foo>(a: T, x: T::A) {}
    |              ^^^ required by this bound in `f1`
 
 error[E0277]: the trait bound `u32: Foo` is not satisfied
-  --> $DIR/associated-types-path-2.rs:35:14
+  --> $DIR/associated-types-path-2.rs:36:5
+   |
+LL |     f1(2u32, 4i32);
+   |     ^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `u32`
+   |
+   = help: the trait `Foo` is implemented for `i32`
+
+error[E0277]: the trait bound `u32: Foo` is not satisfied
+  --> $DIR/associated-types-path-2.rs:36:14
    |
 LL |     f1(2u32, 4i32);
    |              ^^^^ the trait `Foo` is not implemented for `u32`
    |
    = help: the trait `Foo` is implemented for `i32`
 
 error[E0308]: mismatched types
-  --> $DIR/associated-types-path-2.rs:41:18
+  --> $DIR/associated-types-path-2.rs:43:18
    |
 LL |     let _: i32 = f2(2i32);
    |            ---   ^^^^^^^^ expected `i32`, found `u32`
@@ -75,7 +91,7 @@ help: you can convert a `u32` to an `i32` and panic if the converted value doesn
 LL |     let _: i32 = f2(2i32).try_into().unwrap();
    |                          ++++++++++++++++++++
 
-error: aborting due to 6 previous errors
+error: aborting due to 8 previous errors
 
 Some errors have detailed explanations: E0277, E0308.
 For more information about an error, try `rustc --explain E0277`.

src/test/ui/coercion/issue-101066.rs

@@ -0,0 +1,16 @@
+// check-pass
+
+use std::convert::TryFrom;
+
+pub trait FieldElement {
+    type Integer: TryFrom<usize, Error = std::num::TryFromIntError>;
+
+    fn valid_integer_try_from<N>(i: N) -> Result<Self::Integer, ()>
+    where
+        Self::Integer: TryFrom<N>,
+    {
+        Self::Integer::try_from(i).map_err(|_| ())
+    }
+}
+
+fn main() {}

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

@@ -18,11 +18,8 @@ LL |     foo(*x);
    |         ^^ doesn't have a size known at compile-time
    |
    = 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

@@ -1,12 +1,15 @@
 fn main() {
     let _ = Iterator::next(&mut ());
     //~^ ERROR `()` is not an iterator
+    //~| ERROR `()` is not an iterator
+    //~| ERROR `()` is not an iterator
 
     for _ in false {}
     //~^ ERROR `bool` is not an iterator
 
     let _ = Iterator::next(&mut ());
     //~^ ERROR `()` is not an iterator
+    //~| ERROR `()` is not an iterator
 
     other()
 }
@@ -16,9 +19,12 @@ pub fn other() {
 
     let _ = Iterator::next(&mut ());
     //~^ ERROR `()` is not an iterator
+    //~| ERROR `()` is not an iterator
+    //~| ERROR `()` is not an iterator
 
     let _ = Iterator::next(&mut ());
     //~^ ERROR `()` is not an iterator
+    //~| ERROR `()` is not an iterator
 
     for _ in false {}
     //~^ ERROR `bool` is not an iterator

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

@@ -8,8 +8,16 @@ 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]: `bool` is not an iterator
-  --> $DIR/issue-28098.rs:5:14
+  --> $DIR/issue-28098.rs:7:14
    |
 LL |     for _ in false {}
    |              ^^^^^ `bool` is not an iterator
@@ -18,7 +26,7 @@ LL |     for _ in false {}
    = note: required for `bool` to implement `IntoIterator`
 
 error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:8:28
+  --> $DIR/issue-28098.rs:10:28
    |
 LL |     let _ = Iterator::next(&mut ());
    |             -------------- ^^^^^^^ `()` is not an iterator
@@ -28,7 +36,23 @@ LL |     let _ = Iterator::next(&mut ());
    = help: the trait `Iterator` is not implemented for `()`
 
 error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:17:28
+  --> $DIR/issue-28098.rs:10:13
+   |
+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: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:20:28
    |
 LL |     let _ = Iterator::next(&mut ());
    |             -------------- ^^^^^^^ `()` is not an iterator
@@ -38,7 +62,15 @@ LL |     let _ = Iterator::next(&mut ());
    = help: the trait `Iterator` is not implemented for `()`
 
 error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:20:28
+  --> $DIR/issue-28098.rs:20:13
+   |
+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:25:28
    |
 LL |     let _ = Iterator::next(&mut ());
    |             -------------- ^^^^^^^ `()` is not an iterator
@@ -47,15 +79,31 @@ LL |     let _ = Iterator::next(&mut ());
    |
    = help: the trait `Iterator` is not implemented for `()`
 
+error[E0277]: `()` is not an iterator
+  --> $DIR/issue-28098.rs:25:13
+   |
+LL |     let _ = Iterator::next(&mut ());
+   |             ^^^^^^^^^^^^^^^^^^^^^^^ `()` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `()`
+
 error[E0277]: `bool` is not an iterator
-  --> $DIR/issue-28098.rs:23:14
+  --> $DIR/issue-28098.rs:29:14
    |
 LL |     for _ in false {}
    |              ^^^^^ `bool` is not an iterator
    |
    = help: the trait `Iterator` is not implemented for `bool`
    = note: required for `bool` to implement `IntoIterator`
 
-error: aborting due to 6 previous errors
+error[E0277]: `()` is not an iterator
+  --> $DIR/issue-28098.rs:20:13
+   |
+LL |     let _ = Iterator::next(&mut ());
+   |             ^^^^^^^^^^^^^^ `()` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `()`
+
+error: aborting due to 12 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

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

@@ -32,8 +32,14 @@ impl Index<Bar<usize>> for [i32] {
 fn main() {
     Index::index(&[] as &[i32], 2u32);
     //~^ ERROR E0277
+    //~| ERROR E0277
+    //~| ERROR E0277
     Index::index(&[] as &[i32], Foo(2u32));
     //~^ ERROR E0277
+    //~| ERROR E0277
+    //~| ERROR E0277
     Index::index(&[] as &[i32], Bar(2u32));
     //~^ ERROR E0277
+    //~| ERROR E0277
+    //~| ERROR E0277
 }