[cxx-interop] Fix ambiguous methods in long chains of inheritance

Author: susmonteiro

include/swift/AST/ClangModuleLoader.h

@@ -216,6 +216,9 @@ class ClangModuleLoader : public ModuleLoader {
                                           DeclContext *newContext,
                                           ClangInheritanceInfo inheritance) = 0;
 
+  /// Checks if \param decl is the original method or a clone from a base class
+  virtual bool isClonedBaseMemberDecl(ValueDecl *decl) = 0;
+
   /// Emits diagnostics for any declarations named name
   /// whose direct declaration context is a TU.
   virtual void diagnoseTopLevelValue(const DeclName &name) = 0;

include/swift/ClangImporter/ClangImporter.h

@@ -657,6 +657,8 @@ class ClangImporter final : public ClangModuleLoader {
   ValueDecl *importBaseMemberDecl(ValueDecl *decl, DeclContext *newContext,
                                   ClangInheritanceInfo inheritance) override;
 
+  bool isClonedBaseMemberDecl(ValueDecl *decl) override;
+
   /// Emits diagnostics for any declarations named name
   /// whose direct declaration context is a TU.
   void diagnoseTopLevelValue(const DeclName &name) override;

lib/ClangImporter/ClangImporter.cpp

@@ -6311,7 +6311,8 @@ TinyPtrVector<ValueDecl *> ClangRecordMemberLookup::evaluate(
          cast<NominalTypeDecl>(recordDecl)->getCurrentMembersWithoutLoading()) {
       auto namedMember = dyn_cast<ValueDecl>(member);
       if (!namedMember || !namedMember->hasName() ||
-          namedMember->getName().getBaseName() != name)
+          namedMember->getName().getBaseName() != name ||
+          clangModuleLoader->isClonedBaseMemberDecl(namedMember))
         continue;
 
       auto *imported = clangModuleLoader->importBaseMemberDecl(
@@ -7661,6 +7662,7 @@ ValueDecl *ClangImporter::Implementation::importBaseMemberDecl(
   // result in multiple definitions of the same symbol.
   std::pair<ValueDecl *, DeclContext *> key = {decl, newContext};
   auto known = clonedBaseMembers.find(key);
+
   if (known == clonedBaseMembers.end()) {
     ValueDecl *cloned = cloneBaseMemberDecl(decl, newContext, inheritance);
     known = clonedBaseMembers.insert({key, cloned}).first;
@@ -7669,6 +7671,19 @@ ValueDecl *ClangImporter::Implementation::importBaseMemberDecl(
   return known->second;
 }
 
+bool ClangImporter::Implementation::isClonedBaseMemberDecl(ValueDecl *decl) {
+
+  // If this is a cloned decl, we don't want to reclone it
+  if (!decl->hasClangNode()) {
+    for (auto &CBM : clonedBaseMembers) {
+      if (decl == CBM.second)
+        return true;
+    }
+  }
+
+  return false;
+}
+
 size_t ClangImporter::Implementation::getImportedBaseMemberDeclArity(
     const ValueDecl *valueDecl) {
   if (auto *func = dyn_cast<FuncDecl>(valueDecl)) {
@@ -7685,6 +7700,10 @@ ClangImporter::importBaseMemberDecl(ValueDecl *decl, DeclContext *newContext,
   return Impl.importBaseMemberDecl(decl, newContext, inheritance);
 }
 
+bool ClangImporter::isClonedBaseMemberDecl(ValueDecl *decl) {
+  return Impl.isClonedBaseMemberDecl(decl);
+}
+
 void ClangImporter::diagnoseTopLevelValue(const DeclName &name) {
   Impl.diagnoseTopLevelValue(name);
 }

lib/ClangImporter/ImporterImpl.h

@@ -700,6 +700,8 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
   ValueDecl *importBaseMemberDecl(ValueDecl *decl, DeclContext *newContext,
                                   ClangInheritanceInfo inheritance);
 
+  bool isClonedBaseMemberDecl(ValueDecl *decl);
+
   static size_t getImportedBaseMemberDeclArity(const ValueDecl *valueDecl);
 
   // Cache for already-specialized function templates and any thunks they may

test/Interop/Cxx/class/inheritance/inherited-lookup-executable.swift

@@ -6,6 +6,13 @@ import StdlibUnittest
 
 var InheritedMemberTestSuite = TestSuite("Test if inherited lookup works")
 
+struct HasOne {
+  let one: One
+  let iOne: IOne
+  let iiOne: IIOne
+  let iiiOne: IIIOne
+}
+
 InheritedMemberTestSuite.test("Regular methods resolve to base classes") {
   // No inheritance (sanity check)
   let one = One()