Expose hidden snippet suggestions

Author: estebank

src/librustc_errors/diagnostic.rs

@@ -323,6 +323,29 @@ impl Diagnostic {
         self
     }
 
+    /// Prints out a message with for a suggestion without showing the suggested code.
+    ///
+    /// This is intended to be used for suggestions that are obvious in what the changes need to
+    /// be from the message, showing the span label inline would be visually unpleasant
+    /// (marginally overlapping spans or multiline spans) and showing the snippet window wouldn't
+    /// improve understandability.
+    pub fn span_suggestion_hidden(
+        &mut self, sp: Span, msg: &str, suggestion: String, applicability: Applicability
+    ) -> &mut Self {
+        self.suggestions.push(CodeSuggestion {
+            substitutions: vec![Substitution {
+                parts: vec![SubstitutionPart {
+                    snippet: suggestion,
+                    span: sp,
+                }],
+            }],
+            msg: msg.to_owned(),
+            style: SuggestionStyle::HideCodeInline,
+            applicability: applicability,
+        });
+        self
+    }
+
     pub fn set_span<S: Into<MultiSpan>>(&mut self, sp: S) -> &mut Self {
         self.span = sp.into();
         self

src/librustc_errors/diagnostic_builder.rs

@@ -261,6 +261,26 @@ impl<'a> DiagnosticBuilder<'a> {
         );
         self
     }
+
+    pub fn span_suggestion_hidden(
+        &mut self,
+        sp: Span,
+        msg: &str,
+        suggestion: String,
+        applicability: Applicability,
+    ) -> &mut Self {
+        if !self.allow_suggestions {
+            return self
+        }
+        self.diagnostic.span_suggestion_hidden(
+            sp,
+            msg,
+            suggestion,
+            applicability,
+        );
+        self
+    }
+
     forward!(pub fn set_span<S: Into<MultiSpan>>(&mut self, sp: S) -> &mut Self);
     forward!(pub fn code(&mut self, s: DiagnosticId) -> &mut Self);