Auto merge of #38925 - petrochenkov:varass, r=jseyfried

Fix ICE when variant is used as a part of associated path

Fixes #38862
r? @jseyfried

src/librustc_resolve/lib.rs

@@ -2410,13 +2410,15 @@ impl<'a> Resolver<'a> {
 
             match binding {
                 Ok(binding) => {
+                    let def = binding.def();
+                    let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
                     if let Some(next_module) = binding.module() {
                         module = Some(next_module);
-                    } else if binding.def() == Def::Err {
+                    } else if def == Def::Err {
                         return PathResult::NonModule(err_path_resolution());
-                    } else if opt_ns.is_some() && !(opt_ns == Some(MacroNS) && !is_last) {
+                    } else if opt_ns.is_some() && (is_last || maybe_assoc) {
                         return PathResult::NonModule(PathResolution {
-                            base_def: binding.def(),
+                            base_def: def,
                             depth: path.len() - i - 1,
                         });
                     } else {

src/test/compile-fail/resolve-variant-assoc-item.rs

@@ -0,0 +1,17 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+enum E { V }
+use E::V;
+
+fn main() {
+    E::V::associated_item; //~ ERROR failed to resolve. Not a module `V`
+    V::associated_item; //~ ERROR failed to resolve. Not a module `V`
+}

src/test/compile-fail/ufcs-partially-resolved.rs

@@ -55,9 +55,9 @@ fn main() {
     <u8 as E::N>::NN; //~ ERROR unresolved method or associated constant `E::N::NN`
     <u8 as A::N>::NN; //~ ERROR unresolved method or associated constant `A::N::NN`
     let _: <u8 as Tr::Y>::NN; //~ ERROR unresolved associated type `Tr::Y::NN`
-    let _: <u8 as E::Y>::NN; //~ ERROR unresolved associated type `E::Y::NN`
+    let _: <u8 as E::Y>::NN; //~ ERROR failed to resolve. Not a module `Y`
     <u8 as Tr::Y>::NN; //~ ERROR unresolved method or associated constant `Tr::Y::NN`
-    <u8 as E::Y>::NN; //~ ERROR unresolved method or associated constant `E::Y::NN`
+    <u8 as E::Y>::NN; //~ ERROR failed to resolve. Not a module `Y`
 
     let _: <u8 as Dr>::Z; //~ ERROR expected associated type, found method `Dr::Z`
     <u8 as Dr>::X; //~ ERROR expected method or associated constant, found associated type `Dr::X`