Use multispan suggestions more often

* Use more accurate span for `async move` suggestion
* Use more accurate span for deref suggestion
* Use `multipart_suggestion` more often

2 files changed, 38 insertions, 0 deletions

diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index 45661ac1562..8199c44ee2a 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -444,6 +444,30 @@ impl Diagnostic {
         self
     }
 
+    /// Prints out a message with multiple suggested edits of the code.
+    /// See also [`Diagnostic::span_suggestion()`].
+    pub fn multipart_suggestions(
+        &mut self,
+        msg: &str,
+        suggestions: impl Iterator<Item = Vec<(Span, String)>>,
+        applicability: Applicability,
+    ) -> &mut Self {
+        self.suggestions.push(CodeSuggestion {
+            substitutions: suggestions
+                .map(|sugg| Substitution {
+                    parts: sugg
+                        .into_iter()
+                        .map(|(span, snippet)| SubstitutionPart { snippet, span })
+                        .collect(),
+                })
+                .collect(),
+            msg: msg.to_owned(),
+            style: SuggestionStyle::ShowCode,
+            applicability,
+            tool_metadata: Default::default(),
+        });
+        self
+    }
     /// Prints out a message with a suggested edit of the code. If the suggestion is presented
     /// inline, it will only show the message and not the suggestion.
     ///
diff --git a/compiler/rustc_errors/src/diagnostic_builder.rs b/compiler/rustc_errors/src/diagnostic_builder.rs
index 282877d5dd1..d35b2924803 100644
--- a/compiler/rustc_errors/src/diagnostic_builder.rs
+++ b/compiler/rustc_errors/src/diagnostic_builder.rs
@@ -301,6 +301,20 @@ impl<'a> DiagnosticBuilder<'a> {
         self
     }
 
+    /// See [`Diagnostic::multipart_suggestions()`].
+    pub fn multipart_suggestions(
+        &mut self,
+        msg: &str,
+        suggestions: impl Iterator<Item = Vec<(Span, String)>>,
+        applicability: Applicability,
+    ) -> &mut Self {
+        if !self.0.allow_suggestions {
+            return self;
+        }
+        self.0.diagnostic.multipart_suggestions(msg, suggestions, applicability);
+        self
+    }
+
     /// See [`Diagnostic::span_suggestion_short()`].
     pub fn span_suggestion_short(
         &mut self,