Fail gracefully for unterminated conflicts.

lib/conflict.js

@@ -121,14 +121,22 @@ export class Conflict {
       }
 
       const visitor = new ConflictVisitor(merge, editor)
-      lastRow = parseConflict(merge, editor, conflictStartRow, visitor)
-      const conflict = visitor.conflict()
 
-      if (conflicts.length > 0) {
-        conflict.navigator.linkToPrevious(conflicts[conflicts.length - 1])
-      }
+      try {
+        lastRow = parseConflict(merge, editor, conflictStartRow, visitor)
+        const conflict = visitor.conflict()
+
+        if (conflicts.length > 0) {
+          conflict.navigator.linkToPrevious(conflicts[conflicts.length - 1])
+        }
+        conflicts.push(conflict)
+      } catch (e) {
+        if (!e.parserState) throw e
 
-      conflicts.push(conflict)
+        if (!atom.inSpecMode()) {
+          console.error(`Unable to parse conflict: ${e.message}\n${e.stack}`)
+        }
+      }
     })
 
     return conflicts
@@ -349,10 +357,16 @@ const parseConflict = function (merge, editor, row, visitor) {
   // the editor.
   const advanceToBoundary = (boundaryKinds = '<|=>') => {
     let b = isAtBoundary(boundaryKinds)
-    while (b === null && row < editor.getLineCount()) {
+    while (b === null) {
       row += 1
+      if (row > editor.getLastBufferRow()) {
+        const e = new Error('Unterminated conflict side')
+        e.parserState = true
+        throw e
+      }
       b = isAtBoundary(boundaryKinds)
     }
+
     lastBoundary = b
     return b
   }

spec/conflict-spec.coffee

@@ -87,6 +87,22 @@ describe "Conflict", ->
       expect(util.rowRangeFrom cs[1].ours.marker).toEqual([14, 15])
       expect(util.rowRangeFrom cs[1].theirs.marker).toEqual([16, 17])
 
+  describe 'with corrupted diffs', ->
+
+    it 'handles corrupted diff output', ->
+      util.openPath 'corrupted-2way-diff.txt', (editorView) ->
+        cs = Conflict.all({}, editorView.getModel())
+        expect(cs.length).toBe(0)
+
+    it 'handles corrupted diff3 output', ->
+      util.openPath 'corrupted-3way-diff.txt', (editorView) ->
+        cs = Conflict.all({}, editorView.getModel())
+
+        expect(cs.length).toBe(1)
+        expect(util.rowRangeFrom cs[0].ours.marker).toEqual([13, 14])
+        expect(util.rowRangeFrom cs[0].base.marker).toEqual([15, 16])
+        expect(util.rowRangeFrom cs[0].theirs.marker).toEqual([17, 18])
+
   describe 'when rebasing', ->
     [conflict] = []
 

spec/fixtures/corrupted-2way-diff.txt

@@ -0,0 +1,6 @@
+<<<<<<< HEAD
+These are my changes
+=======
+These are your changes
+
+Oops, deleted the end marker.

spec/fixtures/corrupted-3way-diff.txt

@@ -0,0 +1,21 @@
+This is a file containing a corrupted diff3 patch.
+
+<<<<<<< HEAD
+These are my changes
+||||||| merged common ancestors
+These are original texts
+Oops, we never get a separator
+These are your changes
+>>>>>>> master
+
+It also contains a valid one.
+
+<<<<<<< HEAD
+These are my changes
+||||||| merged common ancestors
+These are original texts
+=======
+These are your changes
+>>>>>>> master
+
+And some text after the end.