Improve the diagnostic around impl Trait <-> generic param mismatch

2 files changed, 24 insertions, 0 deletions

diff --git a/src/librustc_errors/diagnostic.rs b/src/librustc_errors/diagnostic.rs
index 75401f21862..81b32f436c8 100644
--- a/src/librustc_errors/diagnostic.rs
+++ b/src/librustc_errors/diagnostic.rs
@@ -259,6 +259,25 @@ impl Diagnostic {
         self
     }
 
+    pub fn multipart_suggestion(
+        &mut self,
+        msg: &str,
+        suggestion: Vec<(Span, String)>,
+    ) -> &mut Self {
+        self.suggestions.push(CodeSuggestion {
+            substitutions: vec![Substitution {
+                parts: suggestion
+                    .into_iter()
+                    .map(|(span, snippet)| SubstitutionPart { snippet, span })
+                    .collect(),
+            }],
+            msg: msg.to_owned(),
+            show_code_when_inline: true,
+            applicability: Applicability::Unspecified,
+        });
+        self
+    }
+
     /// Prints out a message with multiple suggested edits of the code.
     pub fn span_suggestions(&mut self, sp: Span, msg: &str, suggestions: Vec<String>) -> &mut Self {
         self.suggestions.push(CodeSuggestion {
diff --git a/src/librustc_errors/diagnostic_builder.rs b/src/librustc_errors/diagnostic_builder.rs
index 7e9ca8633a5..b813edadc57 100644
--- a/src/librustc_errors/diagnostic_builder.rs
+++ b/src/librustc_errors/diagnostic_builder.rs
@@ -178,6 +178,11 @@ impl<'a> DiagnosticBuilder<'a> {
                                           msg: &str,
                                           suggestion: String)
                                           -> &mut Self);
+    forward!(pub fn multipart_suggestion(
+        &mut self,
+        msg: &str,
+        suggestion: Vec<(Span, String)>
+    ) -> &mut Self);
     forward!(pub fn span_suggestion(&mut self,
                                     sp: Span,
                                     msg: &str,