Eliminate the 'Module' variant from UnqualifiedLookupResult.

Make unqualified lookup always provide a declaration for the things it
finds, rather than providing either a module or a declaration. Unify
various code paths in our type checker now that module declarations
come in with the other declarations.

Swift SVN r28286

Author: DougGregor

include/swift/AST/NameLookup.h

@@ -38,10 +38,7 @@ namespace swift {
 struct UnqualifiedLookupResult {
 private:
   ValueDecl *Base;
-  union {
-    ValueDecl *Value;
-    Module *NamedModule;
-  };
+  ValueDecl *Value;
 
 public:
   /// Kind - The kind of reference.
@@ -77,27 +74,13 @@ struct UnqualifiedLookupResult {
     /// MetaArchetypeMember - "x" refers to a member of the metatype of an
     /// archetype type, which is referred to by BaseDecl. The base is evaluated
     /// and ignored.
-    MetaArchetypeMember,
-
-    /// ModuleName - "x" refers to a module, either the current
-    /// module or an imported module.
-    ModuleName
+    MetaArchetypeMember
   } Kind;
 
-  bool hasValueDecl() const {
-    return Kind != ModuleName;
-  }
-
   ValueDecl *getValueDecl() const {
-    assert(hasValueDecl());
     return Value;
   }
 
-  Module *getNamedModule() const {
-    assert(Kind == ModuleName);
-    return NamedModule;
-  }
-
   ValueDecl *getBaseDecl() const {
     return Base;
   }
@@ -171,14 +154,6 @@ struct UnqualifiedLookupResult {
     R.Kind = MetaArchetypeMember;
     return R;
   }
-
-  static UnqualifiedLookupResult getModuleName(Module *m) {
-    UnqualifiedLookupResult R;
-    R.Base = nullptr;
-    R.NamedModule = m;
-    R.Kind = ModuleName;
-    return R;
-  }
 };
 
 /// \brief This class implements and represents the result of performing

lib/AST/NameLookup.cpp

@@ -739,7 +739,7 @@ UnqualifiedLookup::UnqualifiedLookup(DeclName Name, DeclContext *DC,
 
   // Look for a module with the given name.
   if (Name.isSimpleName(M.getName())) {
-    Results.push_back(Result::getModuleName(&M));
+    Results.push_back(Result::getModuleMember(&M));
     return;
   }
 
@@ -749,7 +749,7 @@ UnqualifiedLookup::UnqualifiedLookup(DeclName Name, DeclContext *DC,
   if (desiredModule) {
     forAllVisibleModules(DC, [&](const Module::ImportedModule &import) -> bool {
       if (import.second == desiredModule) {
-        Results.push_back(Result::getModuleName(import.second));
+        Results.push_back(Result::getModuleMember(import.second));
         return false;
       }
       return true;
@@ -758,7 +758,7 @@ UnqualifiedLookup::UnqualifiedLookup(DeclName Name, DeclContext *DC,
 }
 
 TypeDecl* UnqualifiedLookup::getSingleTypeResult() {
-  if (Results.size() != 1 || !Results.back().hasValueDecl())
+  if (Results.size() != 1)
     return nullptr;
   return dyn_cast<TypeDecl>(Results.back().getValueDecl());
 }

lib/AST/TypeRepr.cpp

@@ -265,7 +265,9 @@ void ComponentIdentTypeRepr::printImpl(ASTPrinter &Printer,
   if (Module *Mod = getBoundModule()) {
     Printer.printModuleRef(Mod, getIdentifier());
   } else if (Type Ty = getBoundType()) {
-    if (auto NTD = Ty->getAnyNominal())
+    if (auto ModuleTy = dyn_cast<ModuleType>(Ty.getPointer()))
+      Printer.printModuleRef(ModuleTy->getModule(), getIdentifier());
+    else if (auto NTD = Ty->getAnyNominal())
       Printer.printTypeRef(NTD, getIdentifier());
     else
       Printer << getIdentifier().str();

lib/ClangImporter/ImportDecl.cpp

@@ -551,9 +551,6 @@ getOperatorRef(ASTContext &C, Identifier name) {
 
   SmallVector<ValueDecl *, 4> found;
   for (auto &result : lookup.Results) {
-    if (!result.hasValueDecl())
-      continue;
-    
     if (!isa<FuncDecl>(result.getValueDecl()))
       continue;
 

lib/IDE/SourceEntityWalker.cpp

@@ -228,8 +228,13 @@ bool SemaAnnotator::walkToTypeReprPre(TypeRepr *T) {
   if (auto IdT = dyn_cast<ComponentIdentTypeRepr>(T)) {
     if (ValueDecl *VD = IdT->getBoundDecl())
       return passReference(VD, IdT->getIdLoc());
-    if (TypeDecl *TyD = getTypeDecl(IdT->getBoundType()))
+    if (TypeDecl *TyD = getTypeDecl(IdT->getBoundType())) {
+      if (ModuleDecl *ModD = dyn_cast<ModuleDecl>(TyD))
+        return passReference(ModD, std::make_pair(IdT->getIdentifier(),
+                                                  IdT->getIdLoc()));
+
       return passReference(TyD, IdT->getIdLoc());
+    }
     if (auto Mod = IdT->getBoundModule())
       return passReference(Mod, std::make_pair(IdT->getIdentifier(),
                                                IdT->getIdLoc()));
@@ -367,6 +372,9 @@ TypeDecl *SemaAnnotator::getTypeDecl(Type Ty) {
 
   if (NameAliasType *NAT = dyn_cast<NameAliasType>(Ty.getPointer()))
     return NAT->getDecl();
+  if (ModuleType *MT = dyn_cast<ModuleType>(Ty.getPointer()))
+    return MT->getModule();
+
   return Ty->getAnyNominal();
 }
 

lib/Immediate/Immediate.cpp

@@ -1330,24 +1330,22 @@ class REPLEnvironment {
           UnqualifiedLookup lookup(ctx.getIdentifier(Tok.getText()),
                                    &REPLInputFile, nullptr);
           for (auto result : lookup.Results) {
-            if (result.hasValueDecl()) {
-              printOrDumpDecl(result.getValueDecl(), doPrint);
+            printOrDumpDecl(result.getValueDecl(), doPrint);
 
-              if (auto typeDecl = dyn_cast<TypeDecl>(result.getValueDecl())) {
-                if (auto typeAliasDecl = dyn_cast<TypeAliasDecl>(typeDecl)) {
-                  TypeDecl *origTypeDecl = typeAliasDecl->getUnderlyingType()
-                    ->getNominalOrBoundGenericNominal();
-                  if (origTypeDecl) {
-                    printOrDumpDecl(origTypeDecl, doPrint);
-                    typeDecl = origTypeDecl;
-                  }
+            if (auto typeDecl = dyn_cast<TypeDecl>(result.getValueDecl())) {
+              if (auto typeAliasDecl = dyn_cast<TypeAliasDecl>(typeDecl)) {
+                TypeDecl *origTypeDecl = typeAliasDecl->getUnderlyingType()
+                  ->getNominalOrBoundGenericNominal();
+                if (origTypeDecl) {
+                  printOrDumpDecl(origTypeDecl, doPrint);
+                  typeDecl = origTypeDecl;
                 }
+              }
 
-                // Print extensions.
-                if (auto nominal = dyn_cast<NominalTypeDecl>(typeDecl)) {
-                  for (auto extension : nominal->getExtensions()) {
-                    printOrDumpDecl(extension, doPrint);
-                  }
+              // Print extensions.
+              if (auto nominal = dyn_cast<NominalTypeDecl>(typeDecl)) {
+                for (auto extension : nominal->getExtensions()) {
+                  printOrDumpDecl(extension, doPrint);
                 }
               }
             }

lib/Parse/ParseSIL.cpp

@@ -763,11 +763,6 @@ static llvm::PointerUnion<ValueDecl*, Module*> lookupTopDecl(Parser &P,
                                                         SourceFile::Parsed);
   UnqualifiedLookup DeclLookup(Name, &P.SF, nullptr);
   assert(DeclLookup.isSuccess() && DeclLookup.Results.size() == 1);
-  if (DeclLookup.Results.back().Kind == UnqualifiedLookupResult::ModuleName) {
-    Module *Mod = DeclLookup.Results.back().getNamedModule();
-    return Mod;
-  }
-  assert(DeclLookup.Results.back().hasValueDecl());
   ValueDecl *VD = DeclLookup.Results.back().getValueDecl();
   return VD;
 }

lib/Sema/TypeCheckAttr.cpp

@@ -1071,17 +1071,15 @@ void AttributeChecker::checkApplicationMainAttribute(DeclAttribute *attr,
                                /*NonCascading=*/true, SourceLoc(),
                                /*IsType=*/false);
   for (const auto &result : lookupMain.Results) {
-    if (result.hasValueDecl())
-      TC.validateDecl(result.getValueDecl());
+    TC.validateDecl(result.getValueDecl());
   }
   auto Foundation = TC.Context.getLoadedModule(C.getIdentifier("Foundation"));
   if (Foundation) {
     UnqualifiedLookup lookupString(C.getIdentifier("NSStringFromClass"),
                                    Foundation, nullptr, /*NonCascading=*/true,
                                    SourceLoc(), /*IsType=*/false);
     for (const auto &result : lookupString.Results) {
-      if (result.hasValueDecl())
-        TC.validateDecl(result.getValueDecl());
+      TC.validateDecl(result.getValueDecl());
     }
   }
 }

lib/Sema/TypeCheckConstraints.cpp

@@ -299,22 +299,10 @@ static Expr *BindName(UnresolvedDeclRefExpr *UDRE, DeclContext *Context,
 
   // FIXME: Need to refactor the way we build an AST node from a lookup result!
 
-  if (!Lookup.Results.empty() &&
-      Lookup.Results[0].Kind == UnqualifiedLookupResult::ModuleName) {
-    assert(Lookup.Results.size() == 1 && "module names should be unique");
-    auto module = Lookup.Results[0].getNamedModule();
-    return new (TC.Context) DeclRefExpr(module, Loc, /*Implicit=*/false,
-                                        AccessSemantics::Ordinary,
-                                        module->getDeclaredType());
-  }
-
   bool AllDeclRefs = true;
   SmallVector<ValueDecl*, 4> ResultValues;
   for (auto Result : Lookup.Results) {
     switch (Result.Kind) {
-      case UnqualifiedLookupResult::ModuleName:
-        llvm_unreachable("handled above");
-
       case UnqualifiedLookupResult::MemberProperty:
       case UnqualifiedLookupResult::MemberFunction:
       case UnqualifiedLookupResult::MetatypeMember:
@@ -353,6 +341,14 @@ static Expr *BindName(UnresolvedDeclRefExpr *UDRE, DeclContext *Context,
   if (!UDRE->isSpecialized() &&
       ResultValues.size() == 1 && UDRE->getRefKind() == DeclRefKind::Ordinary &&
       isa<TypeDecl>(ResultValues[0])) {
+    // FIXME: This is odd.
+    if (isa<ModuleDecl>(ResultValues[0])) {
+      return new (TC.Context) DeclRefExpr(ResultValues[0], Loc,
+                                          /*implicit=*/false,
+                                          AccessSemantics::Ordinary,
+                                          ResultValues[0]->getType());
+    }
+
     return TypeExpr::createForDecl(Loc, cast<TypeDecl>(ResultValues[0]));
   }
 
@@ -410,7 +406,6 @@ static Expr *BindName(UnresolvedDeclRefExpr *UDRE, DeclContext *Context,
         break;
       case UnqualifiedLookupResult::ModuleMember:
       case UnqualifiedLookupResult::LocalDecl:
-      case UnqualifiedLookupResult::ModuleName:
         AllMemberRefs = false;
         break;
       case UnqualifiedLookupResult::MetaArchetypeMember:
@@ -1627,8 +1622,6 @@ bool TypeChecker::typeCheckExprPattern(ExprPattern *EP, DeclContext *DC,
 
   SmallVector<ValueDecl*, 4> choices;
   for (auto &result : matchLookup.Results) {
-    if (!result.hasValueDecl())
-      continue;
     choices.push_back(result.getValueDecl());
   }
 

lib/Sema/TypeCheckPattern.cpp

@@ -38,8 +38,6 @@ lookupUnqualifiedEnumMemberElement(TypeChecker &TC, DeclContext *DC,
   // See if there is any enum element in there.
   EnumElementDecl *foundElement = nullptr;
   for (auto result : lookup.Results) {
-    if (!result.hasValueDecl())
-      continue;
     auto *oe = dyn_cast<EnumElementDecl>(result.getValueDecl());
     if (!oe)
       continue;

lib/Sema/TypeCheckProtocol.cpp

@@ -1923,7 +1923,6 @@ ConformanceChecker::lookupValueWitnesses(ValueDecl *req, bool *ignoringNames) {
 
     if (lookup.isSuccess()) {
       for (auto candidate : lookup.Results) {
-        assert(candidate.hasValueDecl());
         witnesses.push_back(candidate.getValueDecl());
       }
     }