Merge pull request #73337 from apple/egorzhdan/unnamed-subscript-param

[cxx-interop] Do not crash when calling a subscript with unnamed parameter

Author: egorzhdan

lib/ClangImporter/SwiftDeclSynthesizer.cpp

@@ -1692,7 +1692,16 @@ SubscriptDecl *SwiftDeclSynthesizer::makeSubscript(FuncDecl *getter,
                              : rawElementTy;
 
   auto &ctx = ImporterImpl.SwiftContext;
-  auto bodyParams = getterImpl->getParameters();
+
+  assert(getterImpl->getParameters()->size() == 1 &&
+         "subscript can only have 1 parameter");
+  auto bodyParam = ParamDecl::clone(ctx, getterImpl->getParameters()->get(0));
+  // If the subscript parameter is unnamed, give it a name to make sure SILGen
+  // creates a variable for it.
+  if (bodyParam->getName().empty())
+    bodyParam->setName(ctx.getIdentifier("__index"));
+
+  auto bodyParams = ParameterList::create(ctx, bodyParam);
   DeclName name(ctx, DeclBaseName::createSubscript(), bodyParams);
   auto dc = getterImpl->getDeclContext();
 

test/Interop/Cxx/operators/Inputs/member-inline.h

@@ -386,6 +386,16 @@ struct DerivedFromReadWriteIntArray : ReadWriteIntArray {};
 
 struct DerivedFromNonTrivialArrayByVal : NonTrivialArrayByVal {};
 
+struct SubscriptUnnamedParameter {
+  int operator[](int) const { return 123; }
+};
+
+struct SubscriptUnnamedParameterReadWrite {
+  int value = 0;
+  const int &operator[](int) const { return value; }
+  int &operator[](int) { return value; }
+};
+
 struct Iterator {
 private:
   int value = 123;

test/Interop/Cxx/operators/member-inline-module-interface.swift

@@ -211,6 +211,13 @@
 // CHECK:   mutating func __operatorSubscriptConst(_ x: Int32) -> NonTrivial
 // CHECK: }
 
+// CHECK: struct SubscriptUnnamedParameter {
+// CHECK:   subscript(__index: Int32) -> Int32 { get }
+// CHECK: }
+// CHECK: struct SubscriptUnnamedParameterReadWrite {
+// CHECK:   subscript(__index: Int32) -> Int32
+// CHECK: }
+
 // CHECK: struct Iterator {
 // CHECK:   var pointee: Int32 { mutating get set }
 // CHECK:   @available(*, unavailable, message: "use .pointee property")

test/Interop/Cxx/operators/member-inline-silgen.swift

@@ -171,6 +171,15 @@ public func index(_ arr: inout ConstPtrByVal, _ arg: Int32, _ val: Int32) -> Int
 // CHECK:   end_access [[SELFACCESS]] : $*ConstPtrByVal
 // CHECK: } // end sil function '$sSo13ConstPtrByValVySPys5Int32VGSgADcig
 
+public func subscriptUnnamed(_ unnamed: SubscriptUnnamedParameter, _ arg: Int32) -> Int32 { unnamed[arg] }
+// CHECK: sil shared [transparent] @$sSo25SubscriptUnnamedParameterVys5Int32VADcig : $@convention(method) (Int32, SubscriptUnnamedParameter) -> Int32 {
+// CHECK: bb0([[INDEX:%.*]] : $Int32, [[SELF:%.*]] : $SubscriptUnnamedParameter):
+// CHECK:   [[SELFACCESS:%.*]] = alloc_stack $SubscriptUnnamedParameter
+// CHECK:   [[OP:%.*]] = function_ref [[OPERATORNAME:@(_ZNK25SubscriptUnnamedParameterixEi|\?\?ASubscriptUnnamedParameter@@QEBAHH@Z)]] : $@convention(cxx_method) (Int32, @in_guaranteed SubscriptUnnamedParameter) -> Int32
+// CHECK:   [[PTR:%.*]] = apply [[OP]]([[INDEX]], [[SELFACCESS]]) : $@convention(cxx_method) (Int32, @in_guaranteed SubscriptUnnamedParameter) -> Int32
+// CHECK:   dealloc_stack [[SELFACCESS]]
+// CHECK: } // end sil function '$sSo25SubscriptUnnamedParameterVys5Int32VADcig'
+
 // CHECK: sil [clang ReadOnlyIntArray.__operatorSubscriptConst] [[READCLASSNAME]] : $@convention(cxx_method) (Int32, @in_guaranteed ReadOnlyIntArray) -> UnsafePointer<Int32>
 // CHECK: sil [clang ReadWriteIntArray.__operatorSubscript] [[READWRITECLASSNAME]] : $@convention(cxx_method) (Int32, @inout ReadWriteIntArray) -> UnsafeMutablePointer<Int32>
 // CHECK: sil [clang NonTrivialIntArrayByVal.__operatorSubscriptConst] [[READWRITECLASSNAMEBYVAL]] : $@convention(cxx_method) (Int32, @in_guaranteed NonTrivialIntArrayByVal) -> Int32

test/Interop/Cxx/operators/member-inline.swift

@@ -394,6 +394,22 @@ OperatorsTestSuite.test("SubscriptSetterConst") {
   setterConst[0] = 10
 }
 
+OperatorsTestSuite.test("SubscriptUnnamedParameter") {
+  let unnamed = SubscriptUnnamedParameter()
+  expectEqual(123, unnamed[0])
+  expectEqual(123, unnamed[321])
+}
+
+OperatorsTestSuite.test("SubscriptUnnamedParameterReadWrite") {
+  var unnamed = SubscriptUnnamedParameterReadWrite()
+  expectEqual(0, unnamed[0])
+  expectEqual(0, unnamed[321])
+
+  unnamed[456] = 456
+  expectEqual(456, unnamed[0])
+  expectEqual(456, unnamed[321])
+}
+
 OperatorsTestSuite.test("DerivedFromConstIteratorPrivatelyWithUsingDecl.pointee") {
   let stars = DerivedFromConstIteratorPrivatelyWithUsingDecl()
   let res = stars.pointee