Clang importer: remove support for implicit properties.

We decided not to support "implicit" properties, where we import
getter/setter pairs as properties. Rather, we only import a property
when there is an explicit "@Property" in Objective-C. Remove the flag
and supporting code for implicit properties.

Author: DougGregor

include/swift/ClangImporter/ClangImporterOptions.h

@@ -53,10 +53,6 @@ class ClangImporterOptions {
   /// generation.
   bool DetailedPreprocessingRecord = false;
 
-  /// If true, matched getter-like and setter-like methods will be imported as
-  /// properties.
-  bool InferImplicitProperties = false;
-
   /// If true, Clang diagnostics will be dumped to stderr using Clang's
   /// diagnostic printer as well as being passed to Swift's diagnostic engine.
   bool DumpClangDiagnostics = false;

include/swift/Option/FrontendOptions.td

@@ -200,10 +200,6 @@ def disable_availability_checking : Flag<["-"],
   "disable-availability-checking">,
   HelpText<"Disable checking for potentially unavailable APIs">;
 
-def enable_objc_implicit_properties :
-  Flag<["-"], "enable-objc-implicit-properties">,
-  HelpText<"Import Objective-C \"implicit properties\" as properties">;
-
 def enable_omit_needless_words :
   Flag<["-"], "enable-omit-needless-words">,
   HelpText<"Omit needless words when importing Objective-C names">;

lib/ClangImporter/ClangImporter.cpp

@@ -1111,7 +1111,6 @@ Module *ClangImporter::getImportedHeaderModule() const {
 ClangImporter::Implementation::Implementation(ASTContext &ctx,
                                               const ClangImporterOptions &opts)
   : SwiftContext(ctx),
-    InferImplicitProperties(opts.InferImplicitProperties),
     ImportForwardDeclarations(opts.ImportForwardDeclarations),
     OmitNeedlessWords(opts.OmitNeedlessWords),
     InferDefaultArguments(opts.InferDefaultArguments),

lib/ClangImporter/ImportDecl.cpp

@@ -4074,132 +4074,6 @@ namespace {
       }
     }
 
-    /// Finds the counterpart accessor method for \p MD, if one exists, in the
-    /// same lexical context.
-    const clang::ObjCMethodDecl *
-    findImplicitPropertyAccessor(const clang::ObjCMethodDecl *MD) {
-      // FIXME: Do we want to infer class properties?
-      if (!MD->isInstanceMethod())
-        return nullptr;
-
-      // First, collect information about the method we have.
-      clang::Selector sel = MD->getSelector();
-      llvm::SmallString<64> counterpartName;
-      auto numArgs = sel.getNumArgs();
-      clang::QualType propTy;
-
-      if (numArgs > 1)
-        return nullptr;
-
-      if (numArgs == 0) {
-        clang::IdentifierInfo *getterID = sel.getIdentifierInfoForSlot(0);
-        if (!getterID)
-          return nullptr;
-        counterpartName =
-          clang::SelectorTable::constructSetterName(getterID->getName());
-        propTy = MD->getReturnType();
-
-      } else {
-        if (!MD->getReturnType()->isVoidType())
-          return nullptr;
-
-        clang::IdentifierInfo *setterID = sel.getIdentifierInfoForSlot(0);
-        if (!setterID || !setterID->getName().startswith("set"))
-          return nullptr;
-        counterpartName = setterID->getName().substr(3);
-        counterpartName[0] = tolower(counterpartName[0]);
-        propTy = MD->parameters().front()->getType();
-      }
-
-      // Next, look for its counterpart.
-      const clang::ASTContext &clangCtx = Impl.getClangASTContext();
-      auto container = cast<clang::ObjCContainerDecl>(MD->getDeclContext());
-      for (auto method : make_range(container->instmeth_begin(),
-                                    container->instmeth_end())) {
-        // Condition 1: it must be a getter if we have a setter, and vice versa.
-        clang::Selector nextSel = method->getSelector();
-        if (nextSel.getNumArgs() != (1 - numArgs))
-          continue;
-
-        // Condition 2: it must have the name we expect.
-        clang::IdentifierInfo *nextID = nextSel.getIdentifierInfoForSlot(0);
-        if (!nextID)
-          continue;
-        if (nextID->getName() != counterpartName)
-          continue;
-
-        // Condition 3: it must have the right type signature.
-        if (numArgs == 0) {
-          if (!method->getReturnType()->isVoidType())
-            continue;
-          clang::QualType paramTy = method->parameters().front()->getType();
-          if (!clangCtx.hasSameUnqualifiedType(propTy, paramTy))
-            continue;
-        } else {
-          clang::QualType returnTy = method->getReturnType();
-          if (!clangCtx.hasSameUnqualifiedType(propTy, returnTy))
-            continue;
-        }
-
-        return method;
-      }
-
-      return nullptr;
-    }
-
-    /// Creates a computed property VarDecl from the given getter and
-    /// optional setter.
-    Decl *makeImplicitPropertyDecl(Decl *opaqueGetter,
-                                   Decl *opaqueSetter,
-                                   DeclContext *dc) {
-      auto getter = cast<FuncDecl>(opaqueGetter);
-      auto setter = cast_or_null<FuncDecl>(opaqueSetter);
-      assert(!setter || setter->getResultType()->isVoid());
-
-      auto name = getter->getName();
-
-      // Check whether there is a function with the same name as this
-      // property. If so, suppress the property; the user will have to use
-      // the methods directly, to avoid ambiguities.
-      auto containerTy = dc->getDeclaredTypeInContext();
-      VarDecl *overridden = nullptr;
-      SmallVector<ValueDecl *, 2> lookup;
-      dc->lookupQualified(containerTy, name,
-                          NL_QualifiedDefault | NL_KnownNoDependency,
-                          nullptr, lookup);
-      for (auto result : lookup) {
-        if (isa<FuncDecl>(result))
-          return nullptr;
-
-        if (auto var = dyn_cast<VarDecl>(result))
-          overridden = var;
-      }
-
-      // Re-import the type as a property type.
-      auto clangGetter = cast<clang::ObjCMethodDecl>(getter->getClangDecl());
-      auto type = Impl.importType(clangGetter->getReturnType(),
-                                  ImportTypeKind::Property,
-                                  isInSystemModule(dc),
-                                  /*isFullyBridgeable*/true);
-      if (!type)
-        return nullptr;
-      
-      auto result = Impl.createDeclWithClangNode<VarDecl>(clangGetter,
-          /*static*/ false, /*IsLet*/ false,
-          Impl.importSourceLoc(clangGetter->getLocation()),
-          name, type, dc);
-      
-      // Turn this into a computed property.
-      // FIXME: Fake locations for '{' and '}'?
-      result->makeComputed(SourceLoc(), getter, setter, nullptr, SourceLoc());
-      addObjCAttribute(result, None);
-
-      if (overridden)
-        result->setOverriddenDecl(overridden);
-
-      return result;
-    }
-
     static bool
     isPotentiallyConflictingSetter(const clang::ObjCProtocolDecl *proto,
                                    const clang::ObjCMethodDecl *method) {
@@ -4295,28 +4169,6 @@ namespace {
               // if we've failed to import a new property.
               if (cast<FuncDecl>(member)->isAccessor())
                 continue;
-            } else if (Impl.InferImplicitProperties) {
-              // Try to infer properties for matched getter/setter pairs.
-              // Be careful to only do this once per matched pair.
-              if (auto counterpart = findImplicitPropertyAccessor(objcMethod)) {
-                if (auto counterpartImported = Impl.importDecl(counterpart)) {
-                  if (objcMethod->getReturnType()->isVoidType()) {
-                    if (auto prop = makeImplicitPropertyDecl(counterpartImported,
-                                                             member,
-                                                             swiftContext)) {
-                      members.push_back(prop);
-                    } else {
-                      // If we fail to import the implicit property, fall back to
-                      // adding the accessors as members. We have to add BOTH
-                      // accessors here because we already skipped over the other
-                      // one.
-                      members.push_back(member);
-                      members.push_back(counterpartImported);
-                    }
-                  }
-                  continue;
-                }
-              }
             } else if (auto *proto = dyn_cast<clang::ObjCProtocolDecl>(decl)) {
               if (isPotentiallyConflictingSetter(proto, objcMethod))
                 continue;

lib/ClangImporter/ImporterImpl.h

@@ -250,7 +250,6 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
   /// \brief Swift AST context.
   ASTContext &SwiftContext;
 
-  const bool InferImplicitProperties;
   const bool ImportForwardDeclarations;
   const bool OmitNeedlessWords;
   const bool InferDefaultArguments;

lib/Frontend/CompilerInvocation.cpp

@@ -808,9 +808,6 @@ static bool ParseClangImporterArgs(ClangImporterOptions &Opts,
     });
   }
 
-  Opts.InferImplicitProperties |=
-    Args.hasArg(OPT_enable_objc_implicit_properties);
-
   Opts.OmitNeedlessWords |= Args.hasArg(OPT_enable_omit_needless_words);
   Opts.InferDefaultArguments |= Args.hasArg(OPT_enable_infer_default_arguments);
 

test/ClangModules/Inputs/custom-modules/ObjCImplicitProperties.h

@@ -89,11 +89,6 @@ module ObjCParseExtrasSystem [system] {
   export *
 }
 
-module ObjCImplicitProperties {
-  header "ObjCImplicitProperties.h"
-  export *
-}
-
 module ObjCSubscripts {
   header "ObjCSubscripts.h"
   export *

test/ClangModules/Inputs/custom-modules/module.map

@@ -271,11 +271,6 @@ ObjCForwardDeclarations("enable-objc-forward-declarations",
     llvm::cl::desc("Import Objective-C forward declarations when possible"),
     llvm::cl::init(false));
 
-static llvm::cl::opt<bool>
-ImplicitProperties("enable-objc-implicit-properties",
-                   llvm::cl::desc("Implicitly import Objective-C getter/setter pairs as properties"),
-                   llvm::cl::init(false));
-
 static llvm::cl::opt<bool>
 InferDefaultArguments(
   "enable-infer-default-arguments",
@@ -2542,8 +2537,6 @@ int main(int argc, char *argv[]) {
     !options::DisableAccessControl;
   InitInvok.getLangOptions().CodeCompleteInitsInPostfixExpr |=
       options::CodeCompleteInitsInPostfixExpr;
-  InitInvok.getClangImporterOptions().InferImplicitProperties |=
-    options::ImplicitProperties;
   InitInvok.getClangImporterOptions().ImportForwardDeclarations |=
     options::ObjCForwardDeclarations;
   InitInvok.getClangImporterOptions().OmitNeedlessWords |=