Make LookupInModuleRequest a Dependency Sink

It wasn't one in the past because the referenced name tracker was written into by unqualified lookup, which would delegate to this request. Now that it's no longer doing that, we have to capture this edge here for private dependencies.

Author: CodaFi

include/swift/AST/NameLookupRequests.h

@@ -447,7 +447,7 @@ class LookupInModuleRequest
                            QualifiedLookupResult(
                                const DeclContext *, DeclName, NLKind,
                                namelookup::ResolutionKind, const DeclContext *),
-                           RequestFlags::Uncached> {
+                           RequestFlags::Uncached | RequestFlags::DependencySink> {
 public:
   using SimpleRequest::SimpleRequest;
 
@@ -459,6 +459,11 @@ class LookupInModuleRequest
   evaluate(Evaluator &evaluator, const DeclContext *moduleOrFile, DeclName name,
            NLKind lookupKind, namelookup::ResolutionKind resolutionKind,
            const DeclContext *moduleScopeContext) const;
+
+public:
+  // Incremental dependencies
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
+                           QualifiedLookupResult l) const;
 };
 
 /// Perform \c AnyObject lookup for a given member.

lib/AST/NameLookupRequests.cpp

@@ -319,6 +319,24 @@ void DirectLookupRequest::writeDependencySink(
   tracker.addUsedMember(desc.DC, desc.Name.getBaseName());
 }
 
+//----------------------------------------------------------------------------//
+// LookupInModuleRequest computation.
+//----------------------------------------------------------------------------//
+
+void LookupInModuleRequest::writeDependencySink(
+    evaluator::DependencyCollector &reqTracker, QualifiedLookupResult l) const {
+  auto *module = std::get<0>(getStorage());
+  auto member = std::get<1>(getStorage());
+  auto *DC = std::get<4>(getStorage());
+
+  // Decline to record lookups outside our module.
+  if (!DC->getParentSourceFile() ||
+      module->getParentModule() != DC->getParentModule()) {
+    return;
+  }
+  reqTracker.addTopLevelName(member.getBaseName());
+}
+
 //----------------------------------------------------------------------------//
 // LookupConformanceInModuleRequest computation.
 //----------------------------------------------------------------------------//