Fix async-std at the price of breaking half the test suite

- Don't mark impl trait as an error

Author: jyn514

src/librustc_privacy/lib.rs

@@ -778,13 +778,8 @@ impl Visitor<'tcx> for EmbargoVisitor<'tcx> {
             }
             // The interface is empty.
             hir::ItemKind::GlobalAsm(..) => {}
-            hir::ItemKind::OpaqueTy(..) => {
-                // FIXME: This is some serious pessimization intended to workaround deficiencies
-                // in the reachability pass (`middle/reachable.rs`). Types are marked as link-time
-                // reachable if they are returned via `impl Trait`, even from private functions.
-                let exist_level = cmp::max(item_level, Some(AccessLevel::ReachableFromImplTrait));
-                self.reach(item.hir_id, exist_level).generics().predicates().ty();
-            }
+            // assume the type is never reachable - since it's opaque, no one can use it from this interface
+            hir::ItemKind::OpaqueTy(..) => {}
             // Visit everything.
             hir::ItemKind::Const(..)
             | hir::ItemKind::Static(..)

src/librustdoc/core.rs

@@ -449,13 +449,6 @@ pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOpt
             let mut global_ctxt = abort_on_err(queries.global_ctxt(), sess).take();
 
             global_ctxt.enter(|tcx| {
-                // Certain queries assume that some checks were run elsewhere
-                // (see https://github.com/rust-lang/rust/pull/73566#issuecomment-656954425),
-                // so type-check everything other than function bodies in this crate before running lints.
-                // NOTE: this does not call `tcx.analysis()` so that we won't
-                // typeck function bodies or run the default rustc lints.
-                // (see `override_queries` in the `config`)
-                let _ = rustc_typeck::check_crate(tcx);
                 tcx.sess.abort_if_errors();
                 sess.time("missing_docs", || {
                     rustc_lint::check_crate(tcx, rustc_lint::builtin::MissingDoc::new);

src/test/rustdoc-ui/error-in-impl-trait/async.rs

@@ -1,10 +1,7 @@
 // edition:2018
+// check-pass
 
-/// This used to work with ResolveBodyWithLoop.
-/// However now that we ignore type checking instead of modifying the function body,
-/// the return type is seen as `impl Future<Output = u32>`, not a `u32`.
-/// So it no longer allows errors in the function body.
+/// Should compile fine
 pub async fn a() -> u32 {
     error::_in::async_fn()
-    //~^ ERROR failed to resolve
 }

src/test/rustdoc-ui/error-in-impl-trait/async.stderr

@@ -1,5 +1,5 @@
+// check-pass
 // manually desugared version of an `async fn` (but with a closure instead of a generator)
 pub fn a() -> impl Fn() -> u32 {
     || content::doesnt::matter()
-    //~^ ERROR failed to resolve
 }

src/test/rustdoc-ui/error-in-impl-trait/closure.rs

@@ -1,7 +1,7 @@
+// check-pass
 trait ValidTrait {}
 
 /// This has docs
 pub fn f() -> impl ValidTrait {
     Vec::<DoesNotExist>::new()
-    //~^ ERROR failed to resolve
 }

src/test/rustdoc-ui/error-in-impl-trait/closure.stderr

@@ -1,6 +1,6 @@
+// check-pass
 pub trait ValidTrait {}
 /// This returns impl trait
 pub fn g() -> impl ValidTrait {
     (|| error::_in::impl_trait::alias::nested::closure())()
-    //~^ ERROR failed to resolve
 }