Do not ICE on malformed suggestion spans

2 files changed, 21 insertions, 1 deletions

diff --git a/src/librustc_errors/emitter.rs b/src/librustc_errors/emitter.rs
index 526b4e2971b..e37496f7299 100644
--- a/src/librustc_errors/emitter.rs
+++ b/src/librustc_errors/emitter.rs
@@ -1475,6 +1475,11 @@ impl EmitterWriter {
             Some(ref sm) => sm,
             None => return Ok(()),
         };
+        if !suggestion.has_valid_spans(&**sm) {
+            // Suggestions coming from macros can have malformed spans. This is a heavy handed
+            // approach to avoid ICEs by ignoring the suggestion outright.
+            return Ok(());
+        }
 
         let mut buffer = StyledBuffer::new();
 
@@ -1505,7 +1510,9 @@ impl EmitterWriter {
             let show_underline = !(parts.len() == 1 && parts[0].snippet.trim() == complete.trim())
                 && complete.lines().count() == 1;
 
-            let lines = sm.span_to_lines(parts[0].span).unwrap();
+            let lines = sm
+                .span_to_lines(parts[0].span)
+                .expect("span_to_lines failed when emitting suggestion");
 
             assert!(!lines.lines.is_empty());
 
diff --git a/src/librustc_errors/lib.rs b/src/librustc_errors/lib.rs
index e24e8719133..889c84d6da1 100644
--- a/src/librustc_errors/lib.rs
+++ b/src/librustc_errors/lib.rs
@@ -10,6 +10,7 @@
 
 pub use emitter::ColorConfig;
 
+use log::debug;
 use Level::*;
 
 use emitter::{is_case_difference, Emitter, EmitterWriter};
@@ -143,6 +144,18 @@ pub struct SubstitutionPart {
 }
 
 impl CodeSuggestion {
+    /// Suggestions coming from macros can have malformed spans. This is a heavy handed approach
+    /// to avoid ICEs by ignoring the suggestion outright.
+    pub fn has_valid_spans(&self, cm: &SourceMap) -> bool {
+        !self.substitutions.iter().any(|subst| {
+            let invalid = subst.parts.iter().any(|item| cm.is_valid_span(item.span).is_err());
+            if invalid {
+                debug!("malformed span in suggestion: {:?}", subst);
+            }
+            invalid
+        })
+    }
+
     /// Returns the assembled code suggestions, whether they should be shown with an underline
     /// and whether the substitution only differs in capitalization.
     pub fn splice_lines(&self, cm: &SourceMap) -> Vec<(String, Vec<SubstitutionPart>, bool)> {