1 files changed, 19 insertions, 5 deletions

diff --git a/clang/lib/Tooling/Syntax/Mutations.cpp b/clang/lib/Tooling/Syntax/Mutations.cpp
index 7278aff5f18..72458528202 100644
--- a/clang/lib/Tooling/Syntax/Mutations.cpp
+++ b/clang/lib/Tooling/Syntax/Mutations.cpp
@@ -29,30 +29,43 @@ class syntax::MutationsImpl {
 public:
   /// Add a new node with a specified role.
   static void addAfter(syntax::Node *Anchor, syntax::Node *New, NodeRole Role) {
+    assert(Anchor != nullptr);
     assert(New->Parent == nullptr);
     assert(New->NextSibling == nullptr);
     assert(!New->isDetached());
     assert(Role != NodeRole::Detached);
 
     New->Role = static_cast<unsigned>(Role);
-    Anchor->parent()->replaceChildRangeLowLevel(Anchor, Anchor, New);
+    auto *P = Anchor->parent();
+    P->replaceChildRangeLowLevel(Anchor, Anchor, New);
+
+    P->assertInvariants();
   }
 
   /// Replace the node, keeping the role.
   static void replace(syntax::Node *Old, syntax::Node *New) {
+    assert(Old != nullptr);
+    assert(Old->Parent != nullptr);
+    assert(Old->canModify());
     assert(New->Parent == nullptr);
     assert(New->NextSibling == nullptr);
     assert(New->isDetached());
 
     New->Role = Old->Role;
-    Old->parent()->replaceChildRangeLowLevel(findPrevious(Old),
-                                             Old->nextSibling(), New);
+    auto *P = Old->parent();
+    P->replaceChildRangeLowLevel(findPrevious(Old), Old->nextSibling(), New);
+
+    P->assertInvariants();
   }
 
   /// Completely remove the node from its parent.
   static void remove(syntax::Node *N) {
-    N->parent()->replaceChildRangeLowLevel(findPrevious(N), N->nextSibling(),
-                                           /*New=*/nullptr);
+    auto *P = N->parent();
+    P->replaceChildRangeLowLevel(findPrevious(N), N->nextSibling(),
+                                 /*New=*/nullptr);
+
+    P->assertInvariants();
+    N->assertInvariants();
   }
 
 private:
@@ -69,6 +82,7 @@ private:
 };
 
 void syntax::removeStatement(syntax::Arena &A, syntax::Statement *S) {
+  assert(S);
   assert(S->canModify());
 
   if (isa<CompoundStatement>(S->parent())) {