Reduce verbosity of some type ascription errors

* Deduplicate type ascription LHS errors
* Remove duplicated `:` -> `::` suggestion from parse error
* Tweak wording to be more accurate
* Modify `current_type_ascription` to reduce span wrangling
* remove now unnecessary match arm
* Add run-rustfix to appropriate tests

1 files changed, 3 insertions, 0 deletions

diff --git a/src/librustc_session/parse.rs b/src/librustc_session/parse.rs
index b428315b3cd..1b232d7b14d 100644
--- a/src/librustc_session/parse.rs
+++ b/src/librustc_session/parse.rs
@@ -138,6 +138,8 @@ pub struct ParseSess {
     pub reached_eof: Lock<bool>,
     /// Environment variables accessed during the build and their values when they exist.
     pub env_depinfo: Lock<FxHashSet<(Symbol, Option<Symbol>)>>,
+    /// All the type ascriptions expressions that have had a suggestion for likely path typo.
+    pub type_ascription_path_suggestions: Lock<FxHashSet<Span>>,
 }
 
 impl ParseSess {
@@ -164,6 +166,7 @@ impl ParseSess {
             symbol_gallery: SymbolGallery::default(),
             reached_eof: Lock::new(false),
             env_depinfo: Default::default(),
+            type_ascription_path_suggestions: Default::default(),
         }
     }