ASTWalker support for custom attributes on properties.

When we encounter a custom attributes on a property (via a pattern binding),
visit those custom attributes. Provides basic indexing support.

Author: DougGregor

lib/AST/ASTWalker.cpp

@@ -121,7 +121,27 @@ class Traversal : public ASTVisitor<Traversal, Expr*, Stmt*,
   bool visit(ParameterList *PL) {
     return inherited::visit(PL);
   }
-  
+
+  //===--------------------------------------------------------------------===//
+  //                               Attributes
+  //===--------------------------------------------------------------------===//
+  bool visitCustomAttributes(Decl *D) {
+    for (auto *customAttr : D->getAttrs().getAttributes<CustomAttr>()) {
+      CustomAttr *mutableCustomAttr = const_cast<CustomAttr *>(customAttr);
+      if (doIt(mutableCustomAttr->getTypeLoc()))
+        return true;
+
+      if (auto arg = customAttr->getArg()) {
+        if (auto newArg = doIt(arg))
+          mutableCustomAttr->setArg(newArg);
+        else
+          return true;
+      }
+    }
+
+    return false;
+  }
+
   //===--------------------------------------------------------------------===//
   //                                 Decls
   //===--------------------------------------------------------------------===//
@@ -151,6 +171,16 @@ class Traversal : public ASTVisitor<Traversal, Expr*, Stmt*,
   }
 
   bool visitPatternBindingDecl(PatternBindingDecl *PBD) {
+    // If there is a single variable, walk it's attributes.
+    bool isPropertyDelegateBackingProperty = false;
+    if (auto singleVar = PBD->getSingleVar()) {
+      if (visitCustomAttributes(singleVar))
+        return true;
+
+      isPropertyDelegateBackingProperty =
+        singleVar->getOriginalDelegatedProperty() != nullptr;
+    }
+
     unsigned idx = 0U-1;
     for (auto entry : PBD->getPatternList()) {
       ++idx;
@@ -159,6 +189,7 @@ class Traversal : public ASTVisitor<Traversal, Expr*, Stmt*,
       else
         return true;
       if (entry.getInit() &&
+          !isPropertyDelegateBackingProperty &&
           (!entry.isInitializerSubsumed() ||
            Walker.shouldWalkIntoLazyInitializers())) {
 #ifndef NDEBUG

test/Index/property_delegates.swift

@@ -0,0 +1,42 @@
+// RUN: %target-swift-ide-test -print-indexed-symbols -source-filename %s | %FileCheck -check-prefix=CHECK %s
+
+@propertyDelegate
+public struct Wrapper<T> {
+  public var value: T
+
+  public init(initialValue: T) {
+    self.value = initialValue
+  }
+
+  public init(body: () -> T) {
+    self.value = body()
+  }
+}
+
+var globalInt: Int { return 17 }
+
+public struct HasDelegates {
+  @Wrapper
+  public var x: Int = globalInt
+
+  @Wrapper(body: { globalInt })
+  public var y: Int
+
+  @Wrapper(body: { return globalInt })
+  public var z: Int
+}
+
+func useMemberwiseInits(i: Int) {
+  _ = HasDelegates(x: i)
+  _ = HasDelegates(y: Wrapper(initialValue: i))
+}
+
+// CHECK: 19:4 | struct/Swift | Wrapper | s:14swift_ide_test7WrapperV | Ref | rel: 0
+// CHECK: 20:14 | instance-property/Swift | x | s:14swift_ide_test12HasDelegatesV1xSivp | Def,RelChild | rel: 1
+// CHECK: 20:23 | variable/Swift | globalInt | s:14swift_ide_test9globalIntSivp | Ref,Read | rel: 0
+
+// CHECK: 22:4 | struct/Swift | Wrapper | s:14swift_ide_test7WrapperV | Ref | rel: 0
+// CHECK: 22:20 | variable/Swift | globalInt | s:14swift_ide_test9globalIntSivp | Ref,Read | rel: 0
+
+// CHECK: 25:4 | struct/Swift | Wrapper | s:14swift_ide_test7WrapperV | Ref | rel: 0
+// CHECK: 25:27 | variable/Swift | globalInt | s:14swift_ide_test9globalIntSivp | Ref,Read | rel: 0