From 3ae5fed04c94be2f8591c7f4ab76f78ec882cd32 Mon Sep 17 00:00:00 2001
From: Jack Huey <jack.huey@umassmed.edu>
Date: Tue, 6 Apr 2021 15:34:29 -0400
Subject: [PATCH] Fix a couple resolve bugs from binder refactor

---
 compiler/rustc_resolve/src/late/lifetimes.rs    | 16 +++++++++++++++-
 ...3-invalid-associated-type-supertrait-hrtb.rs |  8 ++++++++
 ...valid-associated-type-supertrait-hrtb.stderr |  9 +++++++++
 .../issue-83907-invalid-fn-like-path.rs         |  7 +++++++
 .../issue-83907-invalid-fn-like-path.stderr     | 17 +++++++++++++++++
 5 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.rs
 create mode 100644 src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.stderr
 create mode 100644 src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.rs
 create mode 100644 src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr

diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs
index b89ad867f46ee..70ddfcc9004f1 100644
--- a/compiler/rustc_resolve/src/late/lifetimes.rs
+++ b/compiler/rustc_resolve/src/late/lifetimes.rs
@@ -2659,6 +2659,13 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                 Some(next) => next,
                 None => break None,
             };
+            // See issue #83753. If someone writes an associated type on a non-trait, just treat it as
+            // there being no supertrait HRTBs.
+            match tcx.def_kind(def_id) {
+                DefKind::Trait | DefKind::TraitAlias | DefKind::Impl => {}
+                _ => break None,
+            }
+
             if trait_defines_associated_type_named(def_id) {
                 break Some(bound_vars.into_iter().collect());
             }
@@ -2703,7 +2710,14 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                 | Scope::Supertrait { ref s, .. } => {
                     scope = *s;
                 }
-                Scope::Root => bug!("In fn_like_elision without appropriate scope above"),
+                Scope::Root => {
+                    // See issue #83907. Just bail out from looking inside.
+                    self.tcx.sess.delay_span_bug(
+                        rustc_span::DUMMY_SP,
+                        "In fn_like_elision without appropriate scope above",
+                    );
+                    return;
+                }
             }
         };
         // While not strictly necessary, we gather anon lifetimes *before* actually
diff --git a/src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.rs b/src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.rs
new file mode 100644
index 0000000000000..7f0ea730dd37b
--- /dev/null
+++ b/src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.rs
@@ -0,0 +1,8 @@
+// check-fail
+
+struct Foo {}
+impl Foo {
+    fn bar(foo: Foo<Target = usize>) {}
+    //~^ associated type bindings are not allowed here
+}
+fn main() {}
diff --git a/src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.stderr b/src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.stderr
new file mode 100644
index 0000000000000..f7bdee6336e2d
--- /dev/null
+++ b/src/test/ui/lifetimes/issue-83753-invalid-associated-type-supertrait-hrtb.stderr
@@ -0,0 +1,9 @@
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-83753-invalid-associated-type-supertrait-hrtb.rs:5:21
+   |
+LL |     fn bar(foo: Foo<Target = usize>) {}
+   |                     ^^^^^^^^^^^^^^ associated type not allowed here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0229`.
diff --git a/src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.rs b/src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.rs
new file mode 100644
index 0000000000000..604687ce71126
--- /dev/null
+++ b/src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.rs
@@ -0,0 +1,7 @@
+// check-fail
+
+static STATIC_VAR_FIVE: &One();
+//~^ cannot find type
+//~| free static item without body
+
+fn main() {}
diff --git a/src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr b/src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr
new file mode 100644
index 0000000000000..e57933da558fd
--- /dev/null
+++ b/src/test/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr
@@ -0,0 +1,17 @@
+error: free static item without body
+  --> $DIR/issue-83907-invalid-fn-like-path.rs:3:1
+   |
+LL | static STATIC_VAR_FIVE: &One();
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                               |
+   |                               help: provide a definition for the static: `= <expr>;`
+
+error[E0412]: cannot find type `One` in this scope
+  --> $DIR/issue-83907-invalid-fn-like-path.rs:3:26
+   |
+LL | static STATIC_VAR_FIVE: &One();
+   |                          ^^^ not found in this scope
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0412`.