Stop bailing out from compilation just because there were incoherent traits

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1990,6 +1990,10 @@ pub(super) fn check_type_bounds<'tcx>(
     impl_ty: ty::AssocItem,
     impl_trait_ref: ty::TraitRef<'tcx>,
 ) -> Result<(), ErrorGuaranteed> {
+    // Avoid bogus "type annotations needed `Foo: Bar`" errors on `impl Bar for Foo` in case
+    // other `Foo` impls are incoherent.
+    tcx.ensure().coherent_trait(impl_trait_ref.def_id)?;
+
     let param_env = tcx.param_env(impl_ty.def_id);
     debug!(?param_env);
 

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1005,6 +1005,11 @@ fn check_associated_item(
     enter_wf_checking_ctxt(tcx, span, item_id, |wfcx| {
         let item = tcx.associated_item(item_id);
 
+        // Avoid bogus "type annotations needed `Foo: Bar`" errors on `impl Bar for Foo` in case
+        // other `Foo` impls are incoherent.
+        tcx.ensure()
+            .coherent_trait(tcx.parent(item.trait_item_def_id.unwrap_or(item_id.into())))?;
+
         let self_ty = match item.container {
             ty::TraitContainer => tcx.types.self_param,
             ty::ImplContainer => tcx.type_of(item.container_id(tcx)).instantiate_identity(),
@@ -1291,6 +1296,9 @@ fn check_impl<'tcx>(
                 // therefore don't need to be WF (the trait's `Self: Trait` predicate
                 // won't hold).
                 let trait_ref = tcx.impl_trait_ref(item.owner_id).unwrap().instantiate_identity();
+                // Avoid bogus "type annotations needed `Foo: Bar`" errors on `impl Bar for Foo` in case
+                // other `Foo` impls are incoherent.
+                tcx.ensure().coherent_trait(trait_ref.def_id)?;
                 let trait_ref = wfcx.normalize(
                     ast_trait_ref.path.span,
                     Some(WellFormedLoc::Ty(item.hir_id().expect_owner().def_id)),

compiler/rustc_hir_analysis/src/lib.rs

@@ -169,11 +169,11 @@ pub fn check_crate(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
 
     tcx.sess.time("coherence_checking", || {
         // Check impls constrain their parameters
-        let mut res =
+        let res =
             tcx.hir().try_par_for_each_module(|module| tcx.ensure().check_mod_impl_wf(module));
 
         for &trait_def_id in tcx.all_local_trait_impls(()).keys() {
-            res = res.and(tcx.ensure().coherent_trait(trait_def_id));
+            let _ = tcx.ensure().coherent_trait(trait_def_id);
         }
         // these queries are executed for side-effects (error reporting):
         res.and(tcx.ensure().crate_inherent_impls(()))

compiler/rustc_hir_typeck/src/callee.rs

@@ -41,7 +41,7 @@ pub fn check_legal_trait_for_method_call(
     receiver: Option<Span>,
     expr_span: Span,
     trait_id: DefId,
-) {
+) -> Result<(), ErrorGuaranteed> {
     if tcx.lang_items().drop_trait() == Some(trait_id) {
         let sugg = if let Some(receiver) = receiver.filter(|s| !s.is_empty()) {
             errors::ExplicitDestructorCallSugg::Snippet {
@@ -51,8 +51,9 @@ pub fn check_legal_trait_for_method_call(
         } else {
             errors::ExplicitDestructorCallSugg::Empty(span)
         };
-        tcx.dcx().emit_err(errors::ExplicitDestructorCall { span, sugg });
+        return Err(tcx.dcx().emit_err(errors::ExplicitDestructorCall { span, sugg }));
     }
+    tcx.coherent_trait(trait_id)
 }
 
 #[derive(Debug)]

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -1105,13 +1105,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 let container_id = assoc_item.container_id(tcx);
                 debug!(?def_id, ?container, ?container_id);
                 match container {
-                    ty::TraitContainer => callee::check_legal_trait_for_method_call(
-                        tcx,
-                        path_span,
-                        None,
-                        span,
-                        container_id,
-                    ),
+                    ty::TraitContainer => {
+                        if let Err(e) = callee::check_legal_trait_for_method_call(
+                            tcx,
+                            path_span,
+                            None,
+                            span,
+                            container_id,
+                        ) {
+                            self.set_tainted_by_errors(e);
+                        }
+                    }
                     ty::ImplContainer => {
                         if segments.len() == 1 {
                             // `<T>::assoc` will end up here, and so

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -630,13 +630,15 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
     fn enforce_illegal_method_limitations(&self, pick: &probe::Pick<'_>) {
         // Disallow calls to the method `drop` defined in the `Drop` trait.
         if let Some(trait_def_id) = pick.item.trait_container(self.tcx) {
-            callee::check_legal_trait_for_method_call(
+            if let Err(e) = callee::check_legal_trait_for_method_call(
                 self.tcx,
                 self.span,
                 Some(self.self_expr.span),
                 self.call_expr.span,
                 trait_def_id,
-            )
+            ) {
+                self.set_tainted_by_errors(e);
+            }
         }
     }
 

compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs

@@ -2364,6 +2364,12 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     return e;
                 }
 
+                if let Err(guar) = self.tcx.ensure().coherent_trait(trait_ref.def_id()) {
+                    // Avoid bogus "type annotations needed `Foo: Bar`" errors on `impl Bar for Foo` in case
+                    // other `Foo` impls are incoherent.
+                    return guar;
+                }
+
                 // This is kind of a hack: it frequently happens that some earlier
                 // error prevents types from being fully inferred, and then we get
                 // a bunch of uninteresting errors saying something like "<generic
@@ -2659,6 +2665,14 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 if let Some(e) = self.tainted_by_errors() {
                     return e;
                 }
+
+                if let Err(guar) =
+                    self.tcx.ensure().coherent_trait(self.tcx.parent(data.projection_ty.def_id))
+                {
+                    // Avoid bogus "type annotations needed `Foo: Bar`" errors on `impl Bar for Foo` in case
+                    // other `Foo` impls are incoherent.
+                    return guar;
+                }
                 let subst = data
                     .projection_ty
                     .args

library/core/src/primitive_docs.rs

@@ -448,22 +448,6 @@ mod prim_unit {}
 #[doc(hidden)]
 impl () {}
 
-// Fake impl that's only really used for docs.
-#[cfg(doc)]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Clone for () {
-    fn clone(&self) -> Self {
-        loop {}
-    }
-}
-
-// Fake impl that's only really used for docs.
-#[cfg(doc)]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Copy for () {
-    // empty
-}
-
 #[rustc_doc_primitive = "pointer"]
 #[doc(alias = "ptr")]
 #[doc(alias = "*")]
@@ -1690,23 +1674,3 @@ mod prim_fn {}
 // See src/librustdoc/passes/collect_trait_impls.rs:collect_trait_impls
 #[doc(hidden)]
 impl<Ret, T> fn(T) -> Ret {}
-
-// Fake impl that's only really used for docs.
-#[cfg(doc)]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[doc(fake_variadic)]
-/// This trait is implemented on function pointers with any number of arguments.
-impl<Ret, T> Clone for fn(T) -> Ret {
-    fn clone(&self) -> Self {
-        loop {}
-    }
-}
-
-// Fake impl that's only really used for docs.
-#[cfg(doc)]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[doc(fake_variadic)]
-/// This trait is implemented on function pointers with any number of arguments.
-impl<Ret, T> Copy for fn(T) -> Ret {
-    // empty
-}

tests/ui/associated-consts/issue-105330.rs

@@ -14,5 +14,6 @@ fn foo<A: TraitWAssocConst<A=32>>() { //~ ERROR E0658
 
 fn main<A: TraitWAssocConst<A=32>>() {
     //~^ ERROR E0658
+    //~| ERROR E0131
     foo::<Demo>();
 }

tests/ui/associated-consts/issue-105330.stderr

@@ -43,7 +43,13 @@ LL | impl TraitWAssocConst for impl Demo {
    |
    = note: `impl Trait` is only allowed in arguments and return types of functions and methods
 
-error: aborting due to 5 previous errors
+error[E0131]: `main` function is not allowed to have generic parameters
+  --> $DIR/issue-105330.rs:15:8
+   |
+LL | fn main<A: TraitWAssocConst<A=32>>() {
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `main` cannot have generic parameters
+
+error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0404, E0562, E0658.
-For more information about an error, try `rustc --explain E0404`.
+Some errors have detailed explanations: E0131, E0404, E0562, E0658.
+For more information about an error, try `rustc --explain E0131`.

tests/ui/async-await/in-trait/coherence-constrained.rs

@@ -12,15 +12,13 @@ impl Foo for Bar {
     type T = ();
 
     async fn foo(&self) {}
-    //~^ ERROR type annotations needed: cannot satisfy `<Bar as Foo>::T == ()`
 }
 
 impl Foo for Bar {
     //~^ ERROR conflicting implementations of trait `Foo` for type `Bar`
     type T = ();
 
     async fn foo(&self) {}
-    //~^ ERROR type annotations needed: cannot satisfy `<Bar as Foo>::T == ()`
 }
 
 fn main() {}

tests/ui/async-await/in-trait/coherence-constrained.stderr

@@ -1,25 +1,12 @@
-error[E0284]: type annotations needed: cannot satisfy `<Bar as Foo>::T == ()`
-  --> $DIR/coherence-constrained.rs:14:5
-   |
-LL |     async fn foo(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^ cannot satisfy `<Bar as Foo>::T == ()`
-
-error[E0284]: type annotations needed: cannot satisfy `<Bar as Foo>::T == ()`
-  --> $DIR/coherence-constrained.rs:22:5
-   |
-LL |     async fn foo(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^ cannot satisfy `<Bar as Foo>::T == ()`
-
 error[E0119]: conflicting implementations of trait `Foo` for type `Bar`
-  --> $DIR/coherence-constrained.rs:18:1
+  --> $DIR/coherence-constrained.rs:17:1
    |
 LL | impl Foo for Bar {
    | ---------------- first implementation here
 ...
 LL | impl Foo for Bar {
    | ^^^^^^^^^^^^^^^^ conflicting implementation for `Bar`
 
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0119, E0284.
-For more information about an error, try `rustc --explain E0119`.
+For more information about this error, try `rustc --explain E0119`.

tests/ui/coherence/associated-type2.rs

@@ -0,0 +1,20 @@
+//! A regression test for #120343. The overlap error was previously
+//! silenced in coherence because projecting `<() as ToUnit>::Unit`
+//! failed. Then then silenced the missing items error in the `ToUnit`
+//! impl, causing us to not emit any errors and ICEing due to a
+//! `span_delay_bug`.
+
+trait ToUnit {
+    type Unit;
+}
+
+impl<T> ToUnit for *const T {}
+//~^ ERROR: not all trait items implemented
+
+trait Overlap<T> {}
+
+impl<T> Overlap<T> for T {}
+
+impl<T> Overlap<<*const T as ToUnit>::Unit> for T {}
+
+fn main() {}

tests/ui/coherence/associated-type2.stderr

@@ -0,0 +1,12 @@
+error[E0046]: not all trait items implemented, missing: `Unit`
+  --> $DIR/associated-type2.rs:11:1
+   |
+LL |     type Unit;
+   |     --------- `Unit` from trait
+...
+LL | impl<T> ToUnit for *const T {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `Unit` in implementation
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0046`.

tests/ui/coherence/coherence-blanket-conflicts-with-specific-multidispatch.rs

@@ -22,6 +22,7 @@ struct MyType {
 impl MyTrait<MyType> for MyType {
 //~^ ERROR E0119
     fn get(&self) -> usize { (*self).clone() }
+    //~^ ERROR incompatible type
 }
 
 fn main() { }

tests/ui/coherence/coherence-blanket-conflicts-with-specific-multidispatch.stderr

@@ -7,6 +7,24 @@ LL | impl<T> MyTrait<T> for T {
 LL | impl MyTrait<MyType> for MyType {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `MyType`
 
-error: aborting due to 1 previous error
+error[E0053]: method `get` has an incompatible type for trait
+  --> $DIR/coherence-blanket-conflicts-with-specific-multidispatch.rs:24:22
+   |
+LL |     fn get(&self) -> usize { (*self).clone() }
+   |                      ^^^^^
+   |                      |
+   |                      expected `MyType`, found `usize`
+   |                      help: change the output type to match the trait: `MyType`
+   |
+note: type in trait
+  --> $DIR/coherence-blanket-conflicts-with-specific-multidispatch.rs:8:22
+   |
+LL |     fn get(&self) -> T;
+   |                      ^
+   = note: expected signature `fn(&MyType) -> MyType`
+              found signature `fn(&MyType) -> usize`
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0119`.
+Some errors have detailed explanations: E0053, E0119.
+For more information about an error, try `rustc --explain E0053`.

tests/ui/coherence/coherence-orphan.rs

@@ -9,10 +9,13 @@ struct TheType;
 
 impl TheTrait<usize> for isize { }
 //~^ ERROR E0117
+//~| ERROR not all trait items implemented
 
 impl TheTrait<TheType> for isize { }
+//~^ ERROR not all trait items implemented
 
 impl TheTrait<isize> for TheType { }
+//~^ ERROR not all trait items implemented
 
 impl !Send for Vec<isize> { } //~ ERROR E0117
 //~^ WARNING

tests/ui/coherence/coherence-orphan.stderr

@@ -11,7 +11,7 @@ LL | impl TheTrait<usize> for isize { }
    = note: define and implement a trait or new type instead
 
 error[E0117]: only traits defined in the current crate can be implemented for types defined outside of the crate
-  --> $DIR/coherence-orphan.rs:17:1
+  --> $DIR/coherence-orphan.rs:20:1
    |
 LL | impl !Send for Vec<isize> { }
    | ^^^^^^^^^^^^^^^----------
@@ -22,7 +22,7 @@ LL | impl !Send for Vec<isize> { }
    = note: define and implement a trait or new type instead
 
 warning: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/coherence-orphan.rs:17:1
+  --> $DIR/coherence-orphan.rs:20:1
    |
 LL | impl !Send for Vec<isize> { }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -34,6 +34,31 @@ note: try using the same sequence of generic parameters as the struct definition
   --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
    = note: `#[warn(suspicious_auto_trait_impls)]` on by default
 
-error: aborting due to 2 previous errors; 1 warning emitted
+error[E0046]: not all trait items implemented, missing: `the_fn`
+  --> $DIR/coherence-orphan.rs:10:1
+   |
+LL | impl TheTrait<usize> for isize { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `the_fn` in implementation
+   |
+   = help: implement the missing item: `fn the_fn(&self) { todo!() }`
+
+error[E0046]: not all trait items implemented, missing: `the_fn`
+  --> $DIR/coherence-orphan.rs:14:1
+   |
+LL | impl TheTrait<TheType> for isize { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `the_fn` in implementation
+   |
+   = help: implement the missing item: `fn the_fn(&self) { todo!() }`
+
+error[E0046]: not all trait items implemented, missing: `the_fn`
+  --> $DIR/coherence-orphan.rs:17:1
+   |
+LL | impl TheTrait<isize> for TheType { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `the_fn` in implementation
+   |
+   = help: implement the missing item: `fn the_fn(&self) { todo!() }`
+
+error: aborting due to 5 previous errors; 1 warning emitted
 
-For more information about this error, try `rustc --explain E0117`.
+Some errors have detailed explanations: E0046, E0117.
+For more information about an error, try `rustc --explain E0046`.