[interop][SwiftToCxx] ensure swift::Int and swift::UInt are usable in generic context

Fixes swiftlang#63452

(cherry picked from commit 85a431e)

Author: hyp

lib/PrintAsClang/PrintSwiftToClangCoreScaffold.cpp

@@ -19,6 +19,7 @@
 #include "swift/AST/Type.h"
 #include "swift/IRGen/IRABIDetailsProvider.h"
 #include "swift/IRGen/Linking.h"
+#include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/STLExtras.h"
 
 using namespace swift;
@@ -164,9 +165,26 @@ void printPrimitiveGenericTypeTraits(raw_ostream &os, ASTContext &astContext,
 
       // Pointer types.
       // FIXME: support raw pointers?
-      astContext.getOpaquePointerType()};
-
-  for (Type type : llvm::makeArrayRef(supportedPrimitiveTypes)) {
+      astContext.getOpaquePointerType(),
+
+      astContext.getIntType(), astContext.getUIntType()};
+
+  auto primTypesArray = llvm::makeArrayRef(supportedPrimitiveTypes);
+
+  // Ensure that `long` and `unsigned long` are treated as valid
+  // generic Swift types (`Int` and `UInt`) on platforms
+  // that do define `Int`/`ptrdiff_t` as `long` and don't define `int64_t` to be
+  // `long`.
+  auto &clangTI =
+      astContext.getClangModuleLoader()->getClangASTContext().getTargetInfo();
+  bool isSwiftIntLong =
+      clangTI.getPtrDiffType(0) == clang::TransferrableTargetInfo::SignedLong;
+  bool isInt64Long =
+      clangTI.getInt64Type() == clang::TransferrableTargetInfo::SignedLong;
+  if (!(isSwiftIntLong && !isInt64Long))
+    primTypesArray = primTypesArray.drop_back(2);
+
+  for (Type type : primTypesArray) {
     auto typeInfo = *typeMapping.getKnownCxxTypeInfo(
         type->getNominalOrBoundGenericNominal());
 

test/Interop/SwiftToCxx/core/swift-impl-defs-in-cxx.swift

@@ -93,8 +93,7 @@
 // CHECK-NEXT: SWIFT_IMPORT_STDLIB_SYMBOL extern size_t $sSdN;
 // CHECK-NEXT: // type metadata address for OpaquePointer.
 // CHECK-NEXT: SWIFT_IMPORT_STDLIB_SYMBOL extern size_t $ss13OpaquePointerVN;
-// CHECK-EMPTY:
-// CHECK-NEXT: #ifdef __cplusplus
+// CHECK: #ifdef __cplusplus
 // CHECK-NEXT: }
 // CHECK-NEXT: #endif
 // CHECK-EMPTY:
@@ -224,7 +223,7 @@
 // CHECK-NEXT:   }
 // CHECK-NEXT: };
 // CHECK-EMPTY:
-// CHECK-NEXT: #pragma clang diagnostic pop
+// CHECK: #pragma clang diagnostic pop
 // CHECK-EMPTY:
 // CHECK-NEXT: } // namespace swift
 // CHECK-EMPTY:

test/Interop/SwiftToCxx/stdlib/stdlib-dep-inline-in-cxx.swift

@@ -17,5 +17,10 @@ public func test() -> String {
     return ""
 }
 
+@_expose(Cxx)
+public func testIntArray() -> [Int] {
+    return []
+}
+
 // CHECK: namespace swift SWIFT_PRIVATE_ATTR SWIFT_SYMBOL_MODULE("swift") {
 // CHECK: class SWIFT_SYMBOL("{{.*}}") String final {