Register wf obligation before normalizing in wfcheck

Author: compiler-errors

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -288,7 +288,8 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
 
         let infcx = self.selcx.infcx();
 
-        if obligation.predicate.has_projections() {
+        // Normalizing WellFormed predicates is not sound, see #100041
+        if obligation.predicate.has_projections() && obligation.predicate.allow_normalization() {
             let mut obligations = Vec::new();
             let predicate = crate::traits::project::try_normalize_with_depth_to(
                 self.selcx,

compiler/rustc_typeck/src/check/wfcheck.rs

@@ -991,7 +991,6 @@ fn check_associated_item(
         match item.kind {
             ty::AssocKind::Const => {
                 let ty = tcx.type_of(item.def_id);
-                let ty = wfcx.normalize(span, Some(WellFormedLoc::Ty(item_id)), ty);
                 wfcx.register_wf_obligation(span, loc, ty.into());
             }
             ty::AssocKind::Fn => {
@@ -1012,7 +1011,6 @@ fn check_associated_item(
                 }
                 if item.defaultness(tcx).has_value() {
                     let ty = tcx.type_of(item.def_id);
-                    let ty = wfcx.normalize(span, Some(WellFormedLoc::Ty(item_id)), ty);
                     wfcx.register_wf_obligation(span, loc, ty.into());
                 }
             }
@@ -1188,6 +1186,8 @@ fn check_item_type(tcx: TyCtxt<'_>, item_id: LocalDefId, ty_span: Span, allow_fo
 
     enter_wf_checking_ctxt(tcx, ty_span, item_id, |wfcx| {
         let ty = tcx.type_of(item_id);
+        wfcx.register_wf_obligation(ty_span, Some(WellFormedLoc::Ty(item_id)), ty.into());
+
         let item_ty = wfcx.normalize(ty_span, Some(WellFormedLoc::Ty(item_id)), ty);
 
         let mut forbid_unsized = true;
@@ -1197,8 +1197,6 @@ fn check_item_type(tcx: TyCtxt<'_>, item_id: LocalDefId, ty_span: Span, allow_fo
                 forbid_unsized = false;
             }
         }
-
-        wfcx.register_wf_obligation(ty_span, Some(WellFormedLoc::Ty(item_id)), item_ty.into());
         if forbid_unsized {
             wfcx.register_bound(
                 traits::ObligationCause::new(ty_span, wfcx.body_id, traits::WellFormed(None)),
@@ -1262,7 +1260,6 @@ fn check_impl<'tcx>(
             }
             None => {
                 let self_ty = tcx.type_of(item.def_id);
-                let self_ty = wfcx.normalize(item.span, None, self_ty);
                 wfcx.register_wf_obligation(
                     ast_self_ty.span,
                     Some(WellFormedLoc::Ty(item.hir_id().expect_owner())),
@@ -1475,35 +1472,6 @@ fn check_fn_or_method<'tcx>(
     let tcx = wfcx.tcx();
     let sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), sig);
 
-    // Normalize the input and output types one at a time, using a different
-    // `WellFormedLoc` for each. We cannot call `normalize_associated_types`
-    // on the entire `FnSig`, since this would use the same `WellFormedLoc`
-    // for each type, preventing the HIR wf check from generating
-    // a nice error message.
-    let ty::FnSig { mut inputs_and_output, c_variadic, unsafety, abi } = sig;
-    inputs_and_output = tcx.mk_type_list(inputs_and_output.iter().enumerate().map(|(i, ty)| {
-        wfcx.normalize(
-            span,
-            Some(WellFormedLoc::Param {
-                function: def_id,
-                // Note that the `param_idx` of the output type is
-                // one greater than the index of the last input type.
-                param_idx: i.try_into().unwrap(),
-            }),
-            ty,
-        )
-    }));
-    // Manually call `normalize_associated_types_in` on the other types
-    // in `FnSig`. This ensures that if the types of these fields
-    // ever change to include projections, we will start normalizing
-    // them automatically.
-    let sig = ty::FnSig {
-        inputs_and_output,
-        c_variadic: wfcx.normalize(span, None, c_variadic),
-        unsafety: wfcx.normalize(span, None, unsafety),
-        abi: wfcx.normalize(span, None, abi),
-    };
-
     for (i, (&input_ty, ty)) in iter::zip(sig.inputs(), hir_decl.inputs).enumerate() {
         wfcx.register_wf_obligation(
             ty.span,
@@ -1886,7 +1854,6 @@ impl<'a, 'tcx> WfCheckingCtxt<'a, 'tcx> {
             .map(|field| {
                 let def_id = self.tcx().hir().local_def_id(field.hir_id);
                 let field_ty = self.tcx().type_of(def_id);
-                let field_ty = self.normalize(field.ty.span, None, field_ty);
                 debug!("non_enum_variant: type of field {:?} is {:?}", field, field_ty);
                 AdtField { ty: field_ty, span: field.ty.span, def_id }
             })

src/test/ui/associated-types/defaults-cyclic-fail-1.rs

@@ -24,9 +24,7 @@ impl Tr for u32 {
 // ...but not in an impl that redefines one of the types.
 impl Tr for bool {
     type A = Box<Self::B>;
-    //~^ ERROR overflow evaluating the requirement `<bool as Tr>::B == _`
 }
-// (the error is shown twice for some reason)
 
 impl Tr for usize {
     type B = &'static Self::A;

src/test/ui/associated-types/defaults-cyclic-fail-1.stderr

@@ -1,15 +1,9 @@
-error[E0275]: overflow evaluating the requirement `<bool as Tr>::B == _`
-  --> $DIR/defaults-cyclic-fail-1.rs:26:14
-   |
-LL |     type A = Box<Self::B>;
-   |              ^^^^^^^^^^^^
-
 error[E0275]: overflow evaluating the requirement `<usize as Tr>::A == _`
-  --> $DIR/defaults-cyclic-fail-1.rs:32:14
+  --> $DIR/defaults-cyclic-fail-1.rs:30:14
    |
 LL |     type B = &'static Self::A;
    |              ^^^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0275`.

src/test/ui/associated-types/defaults-cyclic-fail-2.rs

@@ -25,9 +25,7 @@ impl Tr for u32 {
 
 impl Tr for bool {
     type A = Box<Self::B>;
-    //~^ ERROR overflow evaluating the requirement `<bool as Tr>::B == _`
 }
-// (the error is shown twice for some reason)
 
 impl Tr for usize {
     type B = &'static Self::A;

src/test/ui/associated-types/defaults-cyclic-fail-2.stderr

@@ -1,15 +1,9 @@
-error[E0275]: overflow evaluating the requirement `<bool as Tr>::B == _`
-  --> $DIR/defaults-cyclic-fail-2.rs:27:14
-   |
-LL |     type A = Box<Self::B>;
-   |              ^^^^^^^^^^^^
-
 error[E0275]: overflow evaluating the requirement `<usize as Tr>::A == _`
-  --> $DIR/defaults-cyclic-fail-2.rs:33:14
+  --> $DIR/defaults-cyclic-fail-2.rs:31:14
    |
 LL |     type B = &'static Self::A;
    |              ^^^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0275`.

src/test/ui/associated-types/issue-100041.rs

@@ -0,0 +1,23 @@
+trait Wf {
+    type Ty;
+}
+
+impl<T: ?Sized> Wf for T {
+    type Ty = ();
+}
+
+const _: <Vec<str> as Wf>::Ty = ();
+//~^ ERROR the size for values of type `str` cannot be known at compilation time
+
+struct Foo {
+    x: <Vec<str> as Wf>::Ty,
+    //~^ ERROR the size for values of type `str` cannot be known at compilation time
+}
+
+fn foo(x: <Vec<str> as Wf>::Ty) {}
+//~^ ERROR the size for values of type `str` cannot be known at compilation time
+
+fn bar() -> <Vec<str> as Wf>::Ty {}
+//~^ ERROR the size for values of type `str` cannot be known at compilation time
+
+fn main() {}

src/test/ui/associated-types/issue-100041.stderr

@@ -0,0 +1,55 @@
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/issue-100041.rs:9:11
+   |
+LL | const _: <Vec<str> as Wf>::Ty = ();
+   |           ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by a bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+   |
+LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
+   |                ^ required by this bound in `Vec`
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/issue-100041.rs:13:9
+   |
+LL |     x: <Vec<str> as Wf>::Ty,
+   |         ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by a bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+   |
+LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
+   |                ^ required by this bound in `Vec`
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/issue-100041.rs:17:12
+   |
+LL | fn foo(x: <Vec<str> as Wf>::Ty) {}
+   |            ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by a bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+   |
+LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
+   |                ^ required by this bound in `Vec`
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/issue-100041.rs:20:13
+   |
+LL | fn bar() -> <Vec<str> as Wf>::Ty {}
+   |             ^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by a bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+   |
+LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
+   |                ^ required by this bound in `Vec`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0277`.

src/test/ui/associated-types/issue-59324.rs

@@ -22,5 +22,6 @@ pub trait ThriftService<Bug: NotFoo>:
 
 fn with_factory<H>(factory: dyn ThriftService<()>) {}
 //~^ ERROR the trait bound `(): Foo` is not satisfied
+//~| ERROR the trait bound `(): NotFoo` is not satisfied
 
 fn main() {}

src/test/ui/associated-types/issue-59324.stderr

@@ -50,6 +50,18 @@ error[E0277]: the trait bound `(): Foo` is not satisfied
 LL | fn with_factory<H>(factory: dyn ThriftService<()>) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `()`
 
+error[E0277]: the trait bound `(): NotFoo` is not satisfied
+  --> $DIR/issue-59324.rs:23:29
+   |
+LL | fn with_factory<H>(factory: dyn ThriftService<()>) {}
+   |                             ^^^^^^^^^^^^^^^^^^^^^ the trait `NotFoo` is not implemented for `()`
+   |
+note: required by a bound in `Foo`
+  --> $DIR/issue-59324.rs:3:16
+   |
+LL | pub trait Foo: NotFoo {
+   |                ^^^^^^ required by this bound in `Foo`
+
 error[E0277]: the trait bound `Bug: Foo` is not satisfied
   --> $DIR/issue-59324.rs:16:5
    |
@@ -65,6 +77,6 @@ help: consider further restricting this bound
 LL | pub trait ThriftService<Bug: NotFoo + Foo>:
    |                                     +++++
 
-error: aborting due to 5 previous errors
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0277`.