3 files changed, 53 insertions, 0 deletions
diff --git a/src/librustc_errors/diagnostic.rs b/src/librustc_errors/diagnostic.rs
index 2e654fe9929..40e4efb397d 100644
--- a/src/librustc_errors/diagnostic.rs
+++ b/src/librustc_errors/diagnostic.rs
@@ -222,6 +222,7 @@ impl Diagnostic {
             }],
             msg: msg.to_owned(),
             show_code_when_inline: false,
+            approximate: false,
         });
         self
     }
@@ -252,6 +253,7 @@ impl Diagnostic {
             }],
             msg: msg.to_owned(),
             show_code_when_inline: true,
+            approximate: false,
         });
         self
     }
@@ -267,6 +269,41 @@ impl Diagnostic {
             }).collect(),
             msg: msg.to_owned(),
             show_code_when_inline: true,
+            approximate: false,
+        });
+        self
+    }
+
+    /// This is a suggestion that may contain mistakes or fillers and should
+    /// be read and understood by a human.
+    pub fn span_approximate_suggestion(&mut self, sp: Span, msg: &str,
+                                       suggestion: String) -> &mut Self {
+        self.suggestions.push(CodeSuggestion {
+            substitutions: vec![Substitution {
+                parts: vec![SubstitutionPart {
+                    snippet: suggestion,
+                    span: sp,
+                }],
+            }],
+            msg: msg.to_owned(),
+            show_code_when_inline: true,
+            approximate: true,
+        });
+        self
+    }
+
+    pub fn span_approximate_suggestions(&mut self, sp: Span, msg: &str,
+                                        suggestions: Vec<String>) -> &mut Self {
+        self.suggestions.push(CodeSuggestion {
+            substitutions: suggestions.into_iter().map(|snippet| Substitution {
+                parts: vec![SubstitutionPart {
+                    snippet,
+                    span: sp,
+                }],
+            }).collect(),
+            msg: msg.to_owned(),
+            show_code_when_inline: true,
+            approximate: true,
         });
         self
     }
diff --git a/src/librustc_errors/diagnostic_builder.rs b/src/librustc_errors/diagnostic_builder.rs
index 61674ada6fa..2536fc648c7 100644
--- a/src/librustc_errors/diagnostic_builder.rs
+++ b/src/librustc_errors/diagnostic_builder.rs
@@ -186,6 +186,16 @@ impl<'a> DiagnosticBuilder<'a> {
                                      msg: &str,
                                      suggestions: Vec<String>)
                                      -> &mut Self);
+    forward!(pub fn span_approximate_suggestion(&mut self,
+                                                sp: Span,
+                                                msg: &str,
+                                                suggestion: String)
+                                                -> &mut Self);
+    forward!(pub fn span_approximate_suggestions(&mut self,
+                                                 sp: Span,
+                                                 msg: &str,
+                                                 suggestions: Vec<String>)
+                                                 -> &mut 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);
 
diff --git a/src/librustc_errors/lib.rs b/src/librustc_errors/lib.rs
index 3d50c95d3f4..7df467ab0d4 100644
--- a/src/librustc_errors/lib.rs
+++ b/src/librustc_errors/lib.rs
@@ -83,6 +83,12 @@ pub struct CodeSuggestion {
     pub substitutions: Vec<Substitution>,
     pub msg: String,
     pub show_code_when_inline: bool,
+    /// Whether or not the suggestion is approximate
+    ///
+    /// Sometimes we may show suggestions with placeholders,
+    /// which are useful for users but not useful for
+    /// tools like rustfix
+    pub approximate: bool,
 }
 
 #[derive(Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]