Merge pull request #74287 from apple/gaborh/unavailable-generics

[cxx-interop] Fix unavailable generics triggering compilation error

Author: Xazax-hun

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -874,6 +874,11 @@ class ModuleWriter {
       // Emit an unavailable stub for a Swift type.
       if (auto *nmtd = dyn_cast<NominalTypeDecl>(vd)) {
         auto representation = cxx_translation::getDeclRepresentation(vd);
+        if (nmtd->isGeneric()) {
+          auto genericSignature =
+              nmtd->getGenericSignature().getCanonicalSignature();
+          ClangSyntaxPrinter(os).printGenericSignature(genericSignature);
+        }
         os << "class ";
         ClangSyntaxPrinter(os).printBaseName(vd);
         os << " { } SWIFT_UNAVAILABLE_MSG(\"";

test/Interop/SwiftToCxx/unsupported/unsupported-generics-in-cxx.swift

@@ -47,17 +47,61 @@ public class Class1 {
   public var index1: Struct1<UInt32> { .init(rawValue: 123) }
 }
 
+public struct GlyphIndex<IntType: FixedWidthInteger & UnsignedInteger> {
+    private var value: IntType
+
+    init(value: IntType) {
+        self.value = value
+    }
+}
+
+public struct QueryResult<GlyphIndexInt: UnsignedInteger & FixedWidthInteger> {
+    public var glyphIDs: [GlyphIndex<GlyphIndexInt>]
+}
+
+public func makeQueryResult() -> QueryResult<UInt32> { .init(glyphIDs: []) }
+
 // CHECK: supported
 
 // CHECK: class SWIFT_SYMBOL("s:5Decls6Class1C") Class1 : public swift::_impl::RefCountedClass {
 // CHECK: 'index1' cannot be printed
 
+// CHECK: namespace Decls SWIFT_PRIVATE_ATTR SWIFT_SYMBOL_MODULE("Decls") {
+// CHECK: namespace Decls SWIFT_PRIVATE_ATTR SWIFT_SYMBOL_MODULE("Decls") {
+// CHECK: SWIFT_INLINE_THUNK void supportedFunc(const T_0_0& x) noexcept SWIFT_SYMBOL("s:5Decls13supportedFuncyyxlF") {
+
+// CHECK: template<class T_0_0>
+// CHECK-NEXT: #ifdef __cpp_concepts
+// CHECK-NEXT: requires swift::isUsableInGenericContext<T_0_0>
+// CHECK-NEXT: #endif // __cpp_concepts
+// CHECK-NEXT: class GlyphIndex { } SWIFT_UNAVAILABLE_MSG("generic requirements for generic struct 'GlyphIndex' can not yet be represented in C++");
+
+// CHECK: class Proto { } SWIFT_UNAVAILABLE_MSG("protocol 'Proto' can not yet be represented in C++");
+
+// CHECK: template<class T_0_0>
+// CHECK-NEXT: #ifdef __cpp_concepts
+// CHECK-NEXT: requires swift::isUsableInGenericContext<T_0_0>
+// CHECK-NEXT: #endif // __cpp_concepts
+// CHECK-NEXT: class QueryResult { } SWIFT_UNAVAILABLE_MSG("generic requirements for generic struct 'QueryResult' can not yet be represented in C++");
+
 // CHECK: class Struct1 { } SWIFT_UNAVAILABLE_MSG("generic requirements for generic struct 'Struct1' can not yet be represented in C++");
 
 // CHECK: // Unavailable in C++: Swift global function 'unsupportedFunc(_:)'.
 
-// CHECK: class unsupportedGenericClass { } SWIFT_UNAVAILABLE_MSG("generic generic class 'unsupportedGenericClass' can not yet be exposed to C++");
+// CHECK: template<class T_0_0>
+// CHECK-NEXT: #ifdef __cpp_concepts
+// CHECK-NEXT: requires swift::isUsableInGenericContext<T_0_0>
+// CHECK-NEXT: #endif // __cpp_concepts
+// CHECK-NEXT: class unsupportedGenericClass { } SWIFT_UNAVAILABLE_MSG("generic generic class 'unsupportedGenericClass' can not yet be exposed to C++");
 // CHECK-EMPTY:
+// CHECK-NEXT: template<class T_0_0>
+// CHECK-NEXT: #ifdef __cpp_concepts
+// CHECK-NEXT: requires swift::isUsableInGenericContext<T_0_0>
+// CHECK-NEXT: #endif // __cpp_concepts
 // CHECK-NEXT: class unsupportedGenericEnum { } SWIFT_UNAVAILABLE_MSG("generic requirements for generic enum 'unsupportedGenericEnum' can not yet be represented in C++");
 // CHECK-EMPTY:
+// CHECK-NEXT: template<class T_0_0>
+// CHECK-NEXT: #ifdef __cpp_concepts
+// CHECK-NEXT: requires swift::isUsableInGenericContext<T_0_0>
+// CHECK-NEXT: #endif // __cpp_concepts
 // CHECK-NEXT: class unsupportedGenericStruct { } SWIFT_UNAVAILABLE_MSG("generic requirements for generic struct 'unsupportedGenericStruct' can not yet be represented in C++");