AST: Clean up a couple of uses of UnqualifiedLookup

We can use type lookup in more places, and switch a couple of callers
to use qualified lookup instead.

Author: slavapestov

lib/AST/ASTContext.cpp

@@ -868,15 +868,14 @@ StructDecl *ASTContext::getObjCBoolDecl() const {
 ClassDecl *ASTContext::get##NAME##Decl() const { \
   if (!getImpl().NAME##Decl) { \
     if (ModuleDecl *M = getLoadedModule(Id_Foundation)) { \
-      /* Note: use unqualified lookup so we find NSError regardless of */ \
-      /* whether it's defined in the Foundation module or the Clang */ \
-      /* Foundation module it imports. */ \
-      UnqualifiedLookup lookup(getIdentifier(#NAME), M); \
-      if (auto type = lookup.getSingleTypeResult()) { \
-        if (auto classDecl = dyn_cast<ClassDecl>(type)) { \
-          if (classDecl->getGenericParams() == nullptr) { \
-            getImpl().NAME##Decl = classDecl; \
-          } \
+      /* Note: lookupQualified() will search both the Foundation module \
+       * and the Clang Foundation module it imports. */ \
+      SmallVector<ValueDecl *, 1> decls; \
+      M->lookupQualified(M, getIdentifier(#NAME), NL_OnlyTypes, decls); \
+      if (decls.size() == 1 && isa<ClassDecl>(decls[0])) { \
+        auto classDecl = cast<ClassDecl>(decls[0]); \
+        if (classDecl->getGenericParams() == nullptr) { \
+          getImpl().NAME##Decl = classDecl; \
         } \
       } \
     } \

lib/ParseSIL/ParseSIL.cpp

@@ -1170,14 +1170,19 @@ bool SILParser::performTypeLocChecking(TypeLoc &T, bool IsSILType,
 
 /// Find the top-level ValueDecl or Module given a name.
 static llvm::PointerUnion<ValueDecl *, ModuleDecl *>
-lookupTopDecl(Parser &P, DeclBaseName Name) {
+lookupTopDecl(Parser &P, DeclBaseName Name, bool typeLookup) {
   // Use UnqualifiedLookup to look through all of the imports.
   // We have to lie and say we're done with parsing to make this happen.
   assert(P.SF.ASTStage == SourceFile::Parsing &&
          "Unexpected stage during parsing!");
   llvm::SaveAndRestore<SourceFile::ASTStage_t> ASTStage(P.SF.ASTStage,
                                                         SourceFile::Parsed);
-  UnqualifiedLookup DeclLookup(Name, &P.SF);
+
+  UnqualifiedLookup::Options options;
+  if (typeLookup)
+    options |= UnqualifiedLookup::Flags::TypeLookup;
+
+  UnqualifiedLookup DeclLookup(Name, &P.SF, SourceLoc(), options);
   assert(DeclLookup.isSuccess() && DeclLookup.Results.size() == 1);
   ValueDecl *VD = DeclLookup.Results.back().getValueDecl();
   return VD;
@@ -1358,9 +1363,11 @@ bool SILParser::parseSILDottedPathWithoutPound(ValueDecl *&Decl,
     }
   } while (P.consumeIf(tok::period));
 
-  // Look up ValueDecl from a dotted path.
+  // Look up ValueDecl from a dotted path. If there are multiple components,
+  // the first one must be a type declaration.
   ValueDecl *VD;
-  llvm::PointerUnion<ValueDecl*, ModuleDecl *> Res = lookupTopDecl(P, FullName[0]);
+  llvm::PointerUnion<ValueDecl*, ModuleDecl *> Res = lookupTopDecl(
+    P, FullName[0], /*typeLookup=*/FullName.size() > 1);
   // It is possible that the last member lookup can return multiple lookup
   // results. One example is the overloaded member functions.
   if (Res.is<ModuleDecl*>()) {
@@ -5748,7 +5755,8 @@ bool SILParserTUState::parseSILVTable(Parser &P) {
     return true;
 
   // Find the class decl.
-  llvm::PointerUnion<ValueDecl*, ModuleDecl *> Res = lookupTopDecl(P, Name);
+  llvm::PointerUnion<ValueDecl*, ModuleDecl *> Res =
+    lookupTopDecl(P, Name, /*typeLookup=*/true);
   assert(Res.is<ValueDecl*>() && "Class look-up should return a Decl");
   ValueDecl *VD = Res.get<ValueDecl*>();
   if (!VD) {
@@ -5835,7 +5843,8 @@ static ProtocolDecl *parseProtocolDecl(Parser &P, SILParser &SP) {
     return nullptr;
 
   // Find the protocol decl. The protocol can be imported.
-  llvm::PointerUnion<ValueDecl*, ModuleDecl *> Res = lookupTopDecl(P, DeclName);
+  llvm::PointerUnion<ValueDecl*, ModuleDecl *> Res =
+    lookupTopDecl(P, DeclName, /*typeLookup=*/true);
   assert(Res.is<ValueDecl*>() && "Protocol look-up should return a Decl");
   ValueDecl *VD = Res.get<ValueDecl*>();
   if (!VD) {

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -950,11 +950,14 @@ class ObjCPrinter : private DeclVisitor<ObjCPrinter>,
       if (!renamedParsedDeclName.ContextName.empty()) {
         return nullptr;
       }
-      UnqualifiedLookup lookup(renamedDeclName.getBaseIdentifier(),
-                               declContext->getModuleScopeContext(),
-                               SourceLoc(),
-                               UnqualifiedLookup::Flags::TypeLookup);
-      return lookup.getSingleTypeResult();
+      SmallVector<ValueDecl *, 1> decls;
+      declContext->lookupQualified(declContext->getParentModule(),
+                                   renamedDeclName.getBaseIdentifier(),
+                                   NL_OnlyTypes,
+                                   decls);
+      if (decls.size() == 1)
+        return decls[0];
+      return nullptr;
     }
 
     TypeDecl *typeDecl = declContext->getSelfNominalTypeDecl();
@@ -1439,10 +1442,12 @@ class ObjCPrinter : private DeclVisitor<ObjCPrinter>,
              isNSObjectOrAnyHashable(ctx, typeArgs[0])) {
       if (ModuleDecl *M = ctx.getLoadedModule(ctx.Id_Foundation)) {
         if (!NSCopyingType) {
-          UnqualifiedLookup lookup(ctx.getIdentifier("NSCopying"), M);
-          auto type = lookup.getSingleTypeResult();
-          if (type && isa<ProtocolDecl>(type)) {
-            NSCopyingType = type->getDeclaredInterfaceType();
+          SmallVector<ValueDecl *, 1> decls;
+          M->lookupQualified(M, ctx.getIdentifier("NSCopying"),
+                             NL_OnlyTypes, decls);
+          if (decls.size() == 1 && isa<ProtocolDecl>(decls[0])) {
+            NSCopyingType = cast<ProtocolDecl>(decls[0])
+              ->getDeclaredInterfaceType();
           } else {
             NSCopyingType = Type();
           }