Fix an arithmetic overflow in reparser

3 files changed, 11 insertions, 5 deletions

diff --git a/crates/ra_syntax/src/parsing/reparsing.rs b/crates/ra_syntax/src/parsing/reparsing.rs
index ba77a3b6c..b44cca49d 100644
--- a/crates/ra_syntax/src/parsing/reparsing.rs
+++ b/crates/ra_syntax/src/parsing/reparsing.rs
@@ -130,11 +130,11 @@ fn merge_errors(
         if e.offset() <= old_node.range().start() {
             res.push(e)
         } else if e.offset() >= old_node.range().end() {
-            res.push(e.add_offset(TextUnit::of_str(&edit.insert) - edit.delete.len()));
+            res.push(e.add_offset(TextUnit::of_str(&edit.insert), edit.delete.len()));
         }
     }
     for e in new_errors {
-        res.push(e.add_offset(old_node.range().start()));
+        res.push(e.add_offset(old_node.range().start(), 0.into()));
     }
     res
 }
diff --git a/crates/ra_syntax/src/syntax_error.rs b/crates/ra_syntax/src/syntax_error.rs
index bdd431742..4b8c22a57 100644
--- a/crates/ra_syntax/src/syntax_error.rs
+++ b/crates/ra_syntax/src/syntax_error.rs
@@ -48,10 +48,10 @@ impl SyntaxError {
         }
     }
 
-    pub fn add_offset(mut self, plus_offset: TextUnit) -> SyntaxError {
+    pub fn add_offset(mut self, plus_offset: TextUnit, minus_offset: TextUnit) -> SyntaxError {
         self.location = match self.location {
-            Location::Range(range) => Location::Range(range + plus_offset),
-            Location::Offset(offset) => Location::Offset(offset + plus_offset),
+            Location::Range(range) => Location::Range(range + plus_offset - minus_offset),
+            Location::Offset(offset) => Location::Offset(offset + plus_offset - minus_offset),
         };
 
         self
diff --git a/crates/ra_syntax/tests/data/reparse/fuzz-failures/0000.rs b/crates/ra_syntax/tests/data/reparse/fuzz-failures/0000.rs
new file mode 100644
index 000000000..388eb74ed
--- /dev/null
+++ b/crates/ra_syntax/tests/data/reparse/fuzz-failures/0000.rs
@@ -0,0 +1,6 @@
+0
+1
+
+
+
+0
\ No newline at end of file