[cxx-interop] Ignore mutable fields when detecting method mutability

lib/ClangImporter/ClangImporter.cpp

@@ -5652,7 +5652,11 @@ ClangImporter::getCXXFunctionTemplateSpecialization(SubstitutionMap subst,
 
 bool ClangImporter::isCXXMethodMutating(const clang::CXXMethodDecl *method) {
   return isa<clang::CXXConstructorDecl>(method) || !method->isConst() ||
-         method->getParent()->hasMutableFields() ||
+         // method->getParent()->hasMutableFields() ||
+         // FIXME(rdar://91961524): figure out a way to handle mutable fields
+         // without breaking classes from the C++ standard library (e.g.
+         // `std::string` which has a mutable member in old libstdc++ version
+         // used on CentOS 7)
          (method->hasAttrs() &&
           llvm::any_of(method->getAttrs(), [](clang::Attr *a) {
             if (auto swiftAttr = dyn_cast<clang::SwiftAttrAttr>(a)) {

test/Interop/Cxx/class/mutable-members-module-interface.swift

@@ -1,5 +1,7 @@
 // RUN: %target-swift-ide-test -print-module -module-to-print=MutableMembers -I %S/Inputs -source-filename=x -enable-experimental-cxx-interop | %FileCheck %s
 
+// REQUIRES: rdar91961524
+
 // CHECK: struct HasPublicMutableMember {
 // CHECK:   mutating func foo() -> Int32
 // CHECK:   var a: Int32

test/Interop/Cxx/class/mutable-members-typechecker.swift

@@ -1,5 +1,7 @@
 // RUN: %target-typecheck-verify-swift -I %S/Inputs -enable-experimental-cxx-interop
 
+// REQUIRES: rdar91961524
+
 import MutableMembers
 
 let obj = HasPublicMutableMember(a: 42) // expected-note {{change 'let' to 'var' to make it mutable}}

test/Interop/Cxx/class/mutable-members.swift

@@ -2,6 +2,8 @@
 //
 // REQUIRES: executable_test
 
+// REQUIRES: rdar91961524
+
 import StdlibUnittest
 import MutableMembers
 

test/Interop/Cxx/ergonomics/Inputs/implicit-computed-properties.h

@@ -27,25 +27,25 @@ struct NoNameVoidGetter {
 };
 
 struct LongNameAllLower {
-  mutable int value = 42;
+  int value = 42;
   int getfoo() const { return value; }
-  void setfoo(int v) const { value = v; }
+  void setfoo(int v) { value = v; }
 };
 
 struct LongNameAllUpper {
-  mutable int value = 42;
+  int value = 42;
   int getFOO() const { return value; }
-  void setFOO(int v) const { value = v; }
+  void setFOO(int v) { value = v; }
 };
 
 struct UpperCaseMix {
-    mutable int value = 42;
+    int value = 42;
     int getFoo() const { return value; }
     void SetFoo(int v) { value = v; }
 };
 
 struct UpperCaseGetterSetter {
-    mutable int value = 42;
+    int value = 42;
     int GetFoo() const { return value; }
     void SetFoo(int v) { value = v; }
 };
@@ -132,7 +132,7 @@ struct ConstSetter {
 };
 
 struct MultipleArgsSetter {
-  int getX();
+  int getX() const;
   void setX(int a, int b);
 };
 

test/Interop/Cxx/ergonomics/implicit-computed-properties-module-interface.swift

@@ -41,35 +41,35 @@
 // CHECK-NOT:     var
 // CHECK-NEXT:    init()
 // CHECK-NEXT:    init(value: Int32)
-// CHECK-NEXT:    var foo: Int32 { mutating get set }
-// CHECK-NEXT:    mutating func getfoo() -> Int32
+// CHECK-NEXT:    var foo: Int32
+// CHECK-NEXT:    func getfoo() -> Int32
 // CHECK-NEXT:    mutating func setfoo(_ v: Int32)
 // CHECK-NEXT:    var value: Int32
 // CHECK-NEXT: }
 
 // CHECK:      struct LongNameAllUpper {
 // CHECK-NEXT:     init()
 // CHECK-NEXT:     init(value: Int32)
-// CHECK-NEXT:     var foo: Int32 { mutating get set }
-// CHECK-NEXT:     mutating func getFOO() -> Int32
+// CHECK-NEXT:     var foo: Int32
+// CHECK-NEXT:     func getFOO() -> Int32
 // CHECK-NEXT:     mutating func setFOO(_ v: Int32)
 // CHECK-NEXT:     var value: Int32
 // CHECK-NEXT: }
 
 // CHECK:      struct UpperCaseMix {
 // CHECK-NEXT:    init()
 // CHECK-NEXT:    init(value: Int32)
-// CHECK-NEXT:    var foo: Int32 { mutating get set }
-// CHECK-NEXT:    mutating func getFoo() -> Int32
+// CHECK-NEXT:    var foo: Int32
+// CHECK-NEXT:    func getFoo() -> Int32
 // CHECK-NEXT:    mutating func SetFoo(_ v: Int32)
 // CHECK-NEXT:    var value: Int32
 // CHECK-NEXT: }
 
 // CHECK:      struct UpperCaseGetterSetter {
 // CHECK-NEXT:    init()
 // CHECK-NEXT:    init(value: Int32)
-// CHECK-NEXT:    var foo: Int32 { mutating get set }
-// CHECK-NEXT:    mutating func GetFoo() -> Int32
+// CHECK-NEXT:    var foo: Int32
+// CHECK-NEXT:    func GetFoo() -> Int32
 // CHECK-NEXT:    mutating func SetFoo(_ v: Int32)
 // CHECK-NEXT:    var value: Int32
 // CHECK-NEXT: }
@@ -176,19 +176,20 @@
 // CHECK-NEXT:    var val: Int32
 // CHECK-NEXT: }
 
-// CHECK:      struct ConstSetter {
-// CHECK-NEXT:    init()
-// CHECK-NEXT:    init(val: Int32)
-// CHECK-NEXT:    var x: Int32 { mutating get set }
-// CHECK-NEXT:    mutating func getX() -> Int32
-// CHECK-NEXT:    mutating func setX(_ v: Int32)
-// CHECK-NEXT:    var val: Int32
-// CHECK-NEXT: }
+// FIXME: rdar91961524
+// TODO-CHECK:      struct ConstSetter {
+// TODO-CHECK-NEXT:    init()
+// TODO-CHECK-NEXT:    init(val: Int32)
+// TODO-CHECK-NEXT:    var x: Int32 { mutating get set }
+// TODO-CHECK-NEXT:    mutating func getX() -> Int32
+// TODO-CHECK-NEXT:    mutating func setX(_ v: Int32)
+// TODO-CHECK-NEXT:    var val: Int32
+// TODO-CHECK-NEXT: }
 
 // CHECK:      struct MultipleArgsSetter {
 // CHECK-NEXT:    init()
-// CHECK-NEXT:    var x: Int32 { mutating get set }
-// CHECK-NEXT:    mutating func getXMutating() -> Int32
+// CHECK-NEXT:    var x: Int32
+// CHECK-NEXT:    func getX() -> Int32
 // CHECK-NEXT:    mutating func setXMutating(_ a: Int32, _ b: Int32)
 // CHECK-NEXT: }
 

test/Interop/Cxx/stdlib/use-std-string.swift

@@ -17,7 +17,7 @@ import std.string
 var StdStringTestSuite = TestSuite("StdString")
 
 StdStringTestSuite.test("init") {
-    var s = CxxString() // declared as `var` because of outdated libstdc++ on CentOS 7
+    let s = CxxString()
     expectEqual(s.size(), 0)
     expectTrue(s.empty())
 }