Merge #5553

5553: Add fix ranges for diagnostics r=matklad a=SomeoneToIgnore

A follow-up of https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/Less.20red.20in.20the.20code

Now diagnostics can apply fixes in a range that's different from the range used to highlight the diagnostics.
Previous logic did not consider the fix range, having both ranges equal, which could cause a lot of red noise in the editor.
Now, the fix range gets used with the fix, the diagnostics range is used for everything else which allows to improve the error highlighting.

before:
<img width="191" alt="image" src="https://user-images.githubusercontent.com/2690773/88590727-df9a6a00-d063-11ea-97ed-9809c1c5e6e6.png">
after:
<img width="222" alt="image" src="https://user-images.githubusercontent.com/2690773/88590734-e1fcc400-d063-11ea-9b7c-25701cbd5352.png">

`MissingFields` and `MissingPatFields` diagnostics now have the fix range as `ast::RecordFieldList` of the expression with an error (as it was before this PR), and the diagnostics range as a `ast::Path` of the expression, if it's present (do you have any example of `ast::Expr::RecordLit` that has no path btw?).
The rest of the diagnostics have both ranges equal, same as it was before this PR.

Co-authored-by: Kirill Bulatov <[email protected]>

1 files changed, 5 insertions, 20 deletions

diff --git a/crates/ra_hir_expand/src/diagnostics.rs b/crates/ra_hir_expand/src/diagnostics.rs
index 84ba97b14..b138500e7 100644
--- a/crates/ra_hir_expand/src/diagnostics.rs
+++ b/crates/ra_hir_expand/src/diagnostics.rs
@@ -16,35 +16,20 @@
 
 use std::{any::Any, fmt};
 
-use ra_syntax::{SyntaxNode, SyntaxNodePtr};
+use ra_syntax::SyntaxNodePtr;
 
-use crate::{db::AstDatabase, InFile};
+use crate::InFile;
 
 pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
     fn message(&self) -> String;
-    fn source(&self) -> InFile<SyntaxNodePtr>;
+    /// Used in highlighting and related purposes
+    fn display_source(&self) -> InFile<SyntaxNodePtr>;
     fn as_any(&self) -> &(dyn Any + Send + 'static);
     fn is_experimental(&self) -> bool {
         false
     }
 }
 
-pub trait AstDiagnostic {
-    type AST;
-    fn ast(&self, db: &dyn AstDatabase) -> Self::AST;
-}
-
-impl dyn Diagnostic {
-    pub fn syntax_node(&self, db: &impl AstDatabase) -> SyntaxNode {
-        let node = db.parse_or_expand(self.source().file_id).unwrap();
-        self.source().value.to_node(&node)
-    }
-
-    pub fn downcast_ref<D: Diagnostic>(&self) -> Option<&D> {
-        self.as_any().downcast_ref()
-    }
-}
-
 pub struct DiagnosticSink<'a> {
     callbacks: Vec<Box<dyn FnMut(&dyn Diagnostic) -> Result<(), ()> + 'a>>,
     filters: Vec<Box<dyn FnMut(&dyn Diagnostic) -> bool + 'a>>,
@@ -89,7 +74,7 @@ impl<'a> DiagnosticSinkBuilder<'a> {
     }
 
     pub fn on<D: Diagnostic, F: FnMut(&D) + 'a>(mut self, mut cb: F) -> Self {
-        let cb = move |diag: &dyn Diagnostic| match diag.downcast_ref::<D>() {
+        let cb = move |diag: &dyn Diagnostic| match diag.as_any().downcast_ref::<D>() {
             Some(d) => {
                 cb(d);
                 Ok(())