Auto merge of rust-lang#73692 - Dylan-DPC:rollup-ehzsbfw, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - rust-lang#73638 (Remove unused crate imports in 2018 edition crates)
 - rust-lang#73639 (Change heuristic for determining range literal)
 - rust-lang#73646 (Add some regression tests)
 - rust-lang#73652 (Add re-exports to use suggestions)
 - rust-lang#73667 (Update BTreeMap::new() doc)
 - rust-lang#73675 (Update books)

Failed merges:

r? @ghost

Author: bors

src/doc/book

@@ -488,7 +488,7 @@ struct MergeIter<K, V, I: Iterator<Item = (K, V)>> {
 }
 
 impl<K: Ord, V> BTreeMap<K, V> {
-    /// Makes a new empty BTreeMap with a reasonable choice for B.
+    /// Makes a new empty BTreeMap.
     ///
     /// Does not allocate anything on its own.
     ///

src/doc/embedded-book

@@ -1,7 +1,5 @@
 use super::*;
 
-use test;
-
 #[bench]
 #[cfg_attr(miri, ignore)] // isolated Miri does not support benchmarks
 fn bench_push_back_100(b: &mut test::Bencher) {

src/doc/reference

@@ -2,7 +2,6 @@ use super::*;
 
 use rustc_ast::ast;
 use rustc_ast::with_default_globals;
-use rustc_span;
 use rustc_span::source_map::respan;
 use rustc_span::symbol::Ident;
 

src/doc/rust-by-example

@@ -358,7 +358,6 @@ cfg_if! {
         use parking_lot::Mutex as InnerLock;
         use parking_lot::RwLock as InnerRwLock;
 
-        use std;
         use std::thread;
         pub use rayon::{join, scope};
 

src/liballoc/collections/btree/map.rs

@@ -1511,13 +1511,7 @@ pub fn is_range_literal(sm: &SourceMap, expr: &Expr<'_>) -> bool {
     // Check whether a span corresponding to a range expression is a
     // range literal, rather than an explicit struct or `new()` call.
     fn is_lit(sm: &SourceMap, span: &Span) -> bool {
-        let end_point = sm.end_point(*span);
-
-        if let Ok(end_string) = sm.span_to_snippet(end_point) {
-            !(end_string.ends_with('}') || end_string.ends_with(')'))
-        } else {
-            false
-        }
+        sm.span_to_snippet(*span).map(|range_src| range_src.contains("..")).unwrap_or(false)
     };
 
     match expr.kind {

src/liballoc/collections/vec_deque/tests.rs

@@ -643,18 +643,18 @@ impl<'a> Resolver<'a> {
         let not_local_module = crate_name.name != kw::Crate;
         let mut worklist =
             vec![(start_module, Vec::<ast::PathSegment>::new(), true, not_local_module)];
+        let mut worklist_via_import = vec![];
 
-        while let Some((in_module, path_segments, accessible, in_module_is_extern)) = worklist.pop()
+        while let Some((in_module, path_segments, accessible, in_module_is_extern)) =
+            match worklist.pop() {
+                None => worklist_via_import.pop(),
+                Some(x) => Some(x),
+            }
         {
             // We have to visit module children in deterministic order to avoid
             // instabilities in reported imports (#43552).
             in_module.for_each_child(self, |this, ident, ns, name_binding| {
-                // avoid imports entirely
-                if name_binding.is_import() && !name_binding.is_extern_crate() {
-                    return;
-                }
-
-                // avoid non-importable candidates as well
+                // avoid non-importable candidates
                 if !name_binding.is_importable() {
                     return;
                 }
@@ -667,6 +667,17 @@ impl<'a> Resolver<'a> {
                     return;
                 }
 
+                let via_import = name_binding.is_import() && !name_binding.is_extern_crate();
+
+                // There is an assumption elsewhere that paths of variants are in the enum's
+                // declaration and not imported. With this assumption, the variant component is
+                // chopped and the rest of the path is assumed to be the enum's own path. For
+                // errors where a variant is used as the type instead of the enum, this causes
+                // funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`.
+                if via_import && name_binding.is_possibly_imported_variant() {
+                    return;
+                }
+
                 // collect results based on the filter function
                 // avoid suggesting anything from the same module in which we are resolving
                 if ident.name == lookup_ident.name
@@ -724,7 +735,8 @@ impl<'a> Resolver<'a> {
                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
                         // add the module to the lookup
                         if seen_modules.insert(module.def_id().unwrap()) {
-                            worklist.push((module, path_segments, child_accessible, is_extern));
+                            if via_import { &mut worklist_via_import } else { &mut worklist }
+                                .push((module, path_segments, child_accessible, is_extern));
                         }
                     }
                 }