RequirementMachine: Forgot to set ProtocolComponent::InProgress to true

Author: slavapestov

lib/AST/RequirementMachine/RewriteContext.cpp

@@ -626,6 +626,9 @@ void RewriteContext::getProtocolComponentRec(
 
 /// Lazily construct a requirement machine for the given protocol's strongly
 /// connected component (SCC) in the protocol dependency graph.
+///
+/// This can only be called once, to prevent multiple requirement machines
+/// for being built with the same component.
 ArrayRef<const ProtocolDecl *> RewriteContext::getProtocolComponent(
     const ProtocolDecl *proto) {
   auto found = Protos.find(proto);
@@ -650,6 +653,8 @@ ArrayRef<const ProtocolDecl *> RewriteContext::getProtocolComponent(
     abort();
   }
 
+  component.InProgress = true;
+
   return component.Protos;
 }