Remove swift::createTypeChecker

Replace it with the "legacy semantic queries" bit. The remaining client
of this bit is SourceKit, which appears to require this bit be set
conditionally so certain semantic property wrapper requests return
a sentinel value.

We should migrate these requests to a syntactic interface as soon as
possible.

rdar://60516325

Author: CodaFi

include/swift/AST/ASTContext.h

@@ -332,6 +332,32 @@ class ASTContext final {
   llvm::BumpPtrAllocator &
   getAllocator(AllocationArena arena = AllocationArena::Permanent) const;
 
+private:
+  bool SemanticQueriesEnabled = false;
+
+public:
+  /// Returns \c true if legacy semantic AST queries are enabled.
+  ///
+  /// The request evaluator generally subsumes the use of this bit. However,
+  /// there are clients - mostly SourceKit - that rely on the fact that this bit
+  /// being \c false causes some property wrapper requests to return null
+  /// sentinel values. These clients should be migrated off of this interface
+  /// to syntactic requests as soon as possible.
+  ///
+  /// rdar://60516325
+  bool areLegacySemanticQueriesEnabled() const {
+    return SemanticQueriesEnabled;
+  }
+
+  /// Enable "semantic queries".
+  ///
+  /// Setting this bit tells property wrapper requests to return a semantic
+  /// value.  It does not otherwise affect compiler behavior and should be
+  /// removed as soon as possible.
+  void setLegacySemanticQueriesEnabled() {
+    SemanticQueriesEnabled = true;
+  }
+
 public:
   /// Allocate - Allocate memory from the ASTContext bump pointer.
   void *Allocate(unsigned long bytes, unsigned alignment,

include/swift/AST/LookupKinds.h

@@ -62,15 +62,12 @@ enum NLOptions : unsigned {
   /// Include synonyms declared with @_implements()
   NL_IncludeAttributeImplements = 0x100,
 
-  /// Synthesize property wrappers and include them in the lookup results.
-  NL_IncludePropertyWrappers = 0x200,
-
   /// This lookup is known to not add any additional dependencies to the
   /// primary source file.
   ///
   /// \see NL_KnownDependencyMask
   NL_KnownNoDependency =
-      NL_KnownNonCascadingDependency | NL_KnownCascadingDependency,
+      NL_KnownNonCascadingDependency|NL_KnownCascadingDependency,
 
   /// A mask of all options controlling how a lookup should be recorded as a
   /// dependency.
@@ -86,12 +83,10 @@ enum NLOptions : unsigned {
   ///
   /// FIXME: Eventually, add NL_ProtocolMembers to this, once all of the
   /// callers can handle it.
-  NL_QualifiedDefault =
-      NL_RemoveNonVisible | NL_RemoveOverridden | NL_IncludePropertyWrappers,
+  NL_QualifiedDefault = NL_RemoveNonVisible | NL_RemoveOverridden,
 
   /// The default set of options used for unqualified name lookup.
-  NL_UnqualifiedDefault =
-      NL_RemoveNonVisible | NL_RemoveOverridden | NL_IncludePropertyWrappers,
+  NL_UnqualifiedDefault = NL_RemoveNonVisible | NL_RemoveOverridden
 };
 
 static inline NLOptions operator|(NLOptions lhs, NLOptions rhs) {

include/swift/Subsystems.h

@@ -140,12 +140,6 @@ namespace swift {
   /// lib/Sema/PCMacro.cpp for a description of the calls inserted.
   void performPCMacro(SourceFile &SF);
 
-  /// Creates a type checker instance on the given AST context, if it
-  /// doesn't already have one.
-  ///
-  /// \returns a reference to the type checker instance.
-  void createTypeChecker(ASTContext &Ctx);
-
   /// Bind all 'extension' visible from \p SF to the extended nominal.
   void bindExtensions(SourceFile &SF);
 

lib/AST/Decl.cpp

@@ -2998,6 +2998,8 @@ bool ValueDecl::isRecursiveValidation() const {
 Type ValueDecl::getInterfaceType() const {
   auto &ctx = getASTContext();
 
+  assert(ctx.areLegacySemanticQueriesEnabled());
+
   if (auto type =
           evaluateOrDefault(ctx.evaluator,
                             InterfaceTypeRequest{const_cast<ValueDecl *>(this)},

lib/AST/NameLookup.cpp

@@ -1612,8 +1612,8 @@ QualifiedLookupRequest::evaluate(Evaluator &eval, const DeclContext *DC,
 
   // Visit all of the nominal types we know about, discovering any others
   // we need along the way.
+  auto &ctx = DC->getASTContext();
   bool wantProtocolMembers = (options & NL_ProtocolMembers);
-  const bool includesPropertyWrappers = (options & NL_IncludePropertyWrappers);
   while (!stack.empty()) {
     auto current = stack.back();
     stack.pop_back();
@@ -1622,7 +1622,7 @@ QualifiedLookupRequest::evaluate(Evaluator &eval, const DeclContext *DC,
       tracker->addUsedMember({current, member.getBaseName()},isLookupCascading);
 
     // Make sure we've resolved property wrappers, if we need them.
-    if (includesPropertyWrappers) {
+    if (ctx.areLegacySemanticQueriesEnabled()) {
       installPropertyWrapperMembersIfNeeded(current, member);
     }
 

lib/Frontend/Frontend.cpp

@@ -239,7 +239,7 @@ bool CompilerInstance::setUpASTContextIfNeeded() {
   if (setUpModuleLoaders())
     return true;
 
-  createTypeChecker(*Context);
+  Context->setLegacySemanticQueriesEnabled();
   return false;
 }
 

lib/IDE/CodeCompletion.cpp

@@ -1638,7 +1638,7 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
         Importer(static_cast<ClangImporter *>(CurrDeclContext->getASTContext().
           getClangModuleLoader())),
         CompletionContext(CompletionContext) {
-    (void)swift::createTypeChecker(Ctx);
+    Ctx.setLegacySemanticQueriesEnabled();
 
     // Determine if we are doing code completion inside a static method.
     if (CurrDeclContext) {
@@ -4186,7 +4186,7 @@ class CompletionOverrideLookup : public swift::VisibleDeclConsumer {
                            SourceLoc introducerLoc)
       : Sink(Sink), Ctx(Ctx), CurrDeclContext(CurrDeclContext),
         ParsedKeywords(ParsedKeywords), introducerLoc(introducerLoc) {
-    (void)createTypeChecker(Ctx);
+    Ctx.setLegacySemanticQueriesEnabled();
 
     hasFuncIntroducer = isKeywordSpecified("func");
     hasVarIntroducer = isKeywordSpecified("var") ||

lib/Sema/CSGen.cpp

@@ -4405,6 +4405,7 @@ getMemberDecls(InterestedMemberKind Kind) {
 ResolvedMemberResult
 swift::resolveValueMember(DeclContext &DC, Type BaseTy, DeclName Name) {
   ResolvedMemberResult Result;
+  assert(DC.getASTContext().areLegacySemanticQueriesEnabled());
   ConstraintSystem CS(&DC, None);
 
   // Look up all members of BaseTy with the given Name.

lib/Sema/DebuggerTestingTransform.cpp

@@ -243,7 +243,7 @@ class DebuggerTestingTransform : public ASTWalker {
     // TODO: typeCheckExpression() seems to assign types to everything here,
     // but may not be sufficient in some cases.
     Expr *FinalExpr = ClosureCall;
-    (void)swift::createTypeChecker(Ctx);
+    Ctx.setLegacySemanticQueriesEnabled();
     if (!TypeChecker::typeCheckExpression(FinalExpr, getCurrentDeclContext()))
       llvm::report_fatal_error("Could not type-check instrumentation");
 

lib/Sema/IDETypeCheckingRequests.cpp

@@ -56,7 +56,7 @@ static bool isExtensionAppliedInternal(const DeclContext *DC, Type BaseTy,
   if (!ED->isConstrainedExtension())
     return true;
 
-  (void)swift::createTypeChecker(DC->getASTContext());
+  DC->getASTContext().setLegacySemanticQueriesEnabled();
   GenericSignature genericSig = ED->getGenericSignature();
   SubstitutionMap substMap = BaseTy->getContextSubstitutionMap(
       DC->getParentModule(), ED->getExtendedNominal());