Add test cases for special subscript name

Author: ahoppen

test/Interpreter/subscripting.swift

@@ -0,0 +1,17 @@
+// RUN: %target-run-simple-swift | %FileCheck %s
+// REQUIRES: executable_test
+
+// Check that subscripts and functions named subscript can exist side-by-side
+struct Foo {
+  subscript() -> String {
+    return "subscript"
+  }
+  
+  func `subscript`() -> String {
+    return "func"
+  }
+}
+
+let f = Foo()
+print(f[]) // CHECK: subscript
+print(f.subscript()) // CHECK: func

test/SIL/Parser/function_named_subscript.sil

@@ -0,0 +1,23 @@
+// RUN: %target-swift-frontend %s -emit-silgen | %FileCheck %s
+
+// Make sure that we can parse escaped subscripts (representing functions named "subscript") in vtables
+
+sil_stage raw
+
+import Builtin
+import Swift
+import SwiftShims
+
+class SubscriptAsFunction {
+  func `subscript`()
+}
+
+sil hidden @_T04test19SubscriptAsFunctionC9subscriptyyF : $@convention(method) (@guaranteed SubscriptAsFunction) -> () {
+bb0(%0 : $SubscriptAsFunction):
+  return undef : $()
+}
+
+sil_vtable SubscriptAsFunction {
+  // CHECK: #SubscriptAsFunction.`subscript`!1: (SubscriptAsFunction) -> () -> () : _T04test19SubscriptAsFunctionC9subscriptyyF
+  #SubscriptAsFunction.`subscript`!1: (SubscriptAsFunction) -> () -> () : _T04test19SubscriptAsFunctionC9subscriptyyF
+}

test/SILGen/vtables.swift

@@ -171,3 +171,15 @@ class DerivedWithoutDefaults : BaseWithDefaults {
 
 // CHECK-LABEL: sil_vtable DerivedWithoutDefaults {
 // CHECK:         #BaseWithDefaults.a!1: {{.*}} : _T07vtables22DerivedWithoutDefaultsC1a{{[_0-9a-zA-Z]*}}F
+
+
+
+// Escape identifiers that represent special names
+
+class SubscriptAsFunction {
+  func `subscript`() {}
+}
+
+// CHECK-LABEL: sil_vtable SubscriptAsFunction {
+// CHECK-NOT:     #SubscriptAsFunction.subscript
+// CHECK:         #SubscriptAsFunction.`subscript`!1

test/decl/protocol/conforms/fixit_stub.swift

@@ -192,3 +192,9 @@ class Adopter17: ProtocolParallel3, ProtocolParallel4 { // expected-error {{type
   func bar2() {}
 }
 
+protocol ProtocolHasSubscriptFunction {
+  func `subscript`() // expected-note{{protocol requires function 'subscript()' with type '() -> ()'; do you want to add a stub?}} {{74-74=\n    func `subscript`() {\n        <#code#>\n    \}\n}}
+}
+class ProtocolHasSubscriptFunctionAdopter: ProtocolHasSubscriptFunction { // expected-error{{type 'ProtocolHasSubscriptFunctionAdopter' does not conform to protocol 'ProtocolHasSubscriptFunction'}}
+
+}

test/decl/subscript/subscripting.swift

@@ -310,3 +310,12 @@ struct S4 {
     }
   }
 }
+
+// SR-2575
+struct SR2575 {
+  subscript() -> Int {
+    return 1
+  }
+}
+
+SR2575().subscript() // expected-error{{type 'SR2575' has no member 'subscript'}}