[CodeCompletion] Don't include symbols starting with '$_'

rdar://problem/50073762

Author: rintaro

lib/AST/Decl.cpp

@@ -2758,6 +2758,11 @@ bool ValueDecl::shouldHideFromEditor() const {
   if (getBaseName().isEditorPlaceholder())
     return true;
 
+  // '$_' names are reserved by compiler internal.
+  if (!getBaseName().isSpecial() &&
+      getBaseName().getIdentifier().str().startswith("$_"))
+    return true;
+
   return false;
 }
 

test/IDE/complete_property_delegate.swift

@@ -0,0 +1,60 @@
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=CONTEXT | %FileCheck %s -check-prefix=CONTEXT
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=CONTEXT_VARNAME | %FileCheck %s -check-prefix=CONTEXT_VARNAME
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=CONTEXT_DOLLAR_VARNAME | %FileCheck %s -check-prefix=CONTEXT_DOLLAR_VARNAME
+
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=SELF | %FileCheck %s -check-prefix=CONTEXT
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=SELF_VARNAME | %FileCheck %s -check-prefix=CONTEXT_VARNAME
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=SELF_DOLLAR_VARNAME | %FileCheck %s -check-prefix=CONTEXT_DOLLAR_VARNAME
+
+@_propertyWrapper
+struct Lazzzy<T> {
+  var value: T
+
+  init(initialValue: T) { value = initialValue }
+  func delegateOperation() -> Int {}
+}
+
+struct MyMember {
+  var x: Int
+  var y: Int
+  static var zero = MyMember(x: 0, y: 0)
+}
+
+class MyClass {
+  @Lazzzy<MyMember>
+  var foo = .zero
+
+  func test() {
+    let _ = #^CONTEXT^#
+// CONTEXT: Begin completions
+// CONTEXT-DAG: Decl[InstanceVar]/CurrNominal:      foo[#MyMember#];
+// CONTEXT-DAG: Decl[InstanceVar]/CurrNominal:      $foo[#Lazzzy<MyMember>#];
+// CONTEXT-NOT: $_
+// CONTEXT: End completions
+
+    let _ = foo.#^CONTEXT_VARNAME^#
+// CONTEXT_VARNAME: Begin completions, 3 items
+// CONTEXT_VARNAME-DAG: Keyword[self]/CurrNominal:          self[#MyMember#]; name=self
+// CONTEXT_VARNAME-DAG: Decl[InstanceVar]/CurrNominal:      x[#Int#]; name=x
+// CONTEXT_VARNAME-DAG: Decl[InstanceVar]/CurrNominal:      y[#Int#]; name=y
+// CONTEXT_VARNAME-NOT: $_
+// CONTEXT_VARNAME-DAG: End completions
+
+    let _ = $foo.#^CONTEXT_DOLLAR_VARNAME^#
+// CONTEXT_DOLLAR_VARNAME: Begin completions, 3 items
+// CONTEXT_DOLLAR_VARNAME-DAG: Keyword[self]/CurrNominal:          self[#Lazzzy<MyMember>#]; name=self
+// CONTEXT_DOLLAR_VARNAME-DAG: Decl[InstanceVar]/CurrNominal:      value[#MyMember#]; name=value
+// CONTEXT_DOLLAR_VARNAME-DAG: Decl[InstanceMethod]/CurrNominal:   delegateOperation()[#Int#]; name=delegateOperation()
+// CONTEXT_DOLLAR_VARNAME-NOT: $_
+// CONTEXT_DOLLAR_VARNAME: End completions
+
+    let _ = self.#^SELF^#
+// Same as CONTEXT.
+
+    let _ = self.foo.#^SELF_VARNAME^#
+// Same as CONTEXT_VARNAME.
+
+    let _ = self.$foo.#^SELF_DOLLAR_VARNAME^#
+// Same as CONTEXT_DOLLAR_VARNAME.
+  }
+}