[interop][SwiftToCxx] experimentally expose Swift's Array type

This is done without annotations on the stdlib yet while @_expose is still experimental

Author: hyp

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -2513,6 +2513,8 @@ static bool hasExposeAttr(const ValueDecl *VD) {
   if (isa<NominalTypeDecl>(VD) && VD->getModuleContext()->isStdlibModule()) {
     if (VD == VD->getASTContext().getStringDecl())
       return true;
+    if (VD == VD->getASTContext().getArrayDecl())
+      return true;
     return false;
   }
   if (VD->getAttrs().hasAttribute<ExposeAttr>())

test/Interop/SwiftToCxx/stdlib/array/array-execution.cpp

@@ -0,0 +1,46 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -parse-as-library %platform-module-dir/Swift.swiftmodule/%module-target-triple.swiftinterface -enable-library-evolution -disable-objc-attr-requires-foundation-module -typecheck -module-name Swift -parse-stdlib -enable-experimental-cxx-interop -emit-clang-header-path %t/Swift.h  -experimental-skip-all-function-bodies
+
+// RUN: %target-swift-frontend -typecheck %t/use-array.swift -typecheck -module-name UseArray -enable-experimental-cxx-interop -emit-clang-header-path %t/UseArray.h
+
+// RUN: %target-interop-build-clangxx -fno-exceptions -std=gnu++20 -c %t/array-execution.cpp -I %t -o %t/swift-stdlib-execution.o
+// RUN: %target-build-swift %t/use-array.swift -o %t/swift-stdlib-execution -Xlinker %t/swift-stdlib-execution.o -module-name UseArray -Xfrontend -entry-point-function-name -Xfrontend swiftMain
+// RUN: %target-codesign %t/swift-stdlib-execution
+// RUN: %target-run %t/swift-stdlib-execution | %FileCheck %s
+
+// REQUIRES: executable_test
+
+//--- use-array.swift
+@_expose(Cxx)
+public func createArray(_ val: CInt) -> [CInt] {
+    return [val, val]
+}
+
+@_expose(Cxx)
+public func passthroughArray(_ val: [CInt]) -> Array<CInt> {
+    return val
+}
+
+@_expose(Cxx)
+public func printArray(_ val: Array<CInt>) {
+    print(val)
+}
+
+//--- array-execution.cpp
+
+#include <cassert>
+#include "Swift.h"
+#include "UseArray.h"
+
+int main() {
+  using namespace Swift;
+
+  {
+    Array<int> val = UseArray::createArray(2);
+    UseArray::printArray(UseArray::passthroughArray(val));
+  }
+// CHECK: [2, 2]
+  return 0;
+}

test/Interop/SwiftToCxx/stdlib/string/string-to-nsstring.mm

@@ -5,12 +5,12 @@
 
 // RUN: %target-swift-frontend -typecheck %t/create_string.swift -typecheck -module-name StringCreator -enable-experimental-cxx-interop -emit-clang-header-path %t/StringCreator.h
 
-// RUN: %target-interop-build-clangxx -fobjc-arc -c %t/string-to-nsstring.mm -I %t -o %t/swift-stdlib-execution.o
+// RUN: %target-interop-build-clangxx -std=gnu++20 -fobjc-arc -c %t/string-to-nsstring.mm -I %t -o %t/swift-stdlib-execution.o
 // RUN: %target-build-swift %t/use_foundation.swift %t/create_string.swift -o %t/swift-stdlib-execution -Xlinker %t/swift-stdlib-execution.o -module-name StringCreator -Xfrontend -entry-point-function-name -Xfrontend swiftMain -lc++
 // RUN: %target-codesign %t/swift-stdlib-execution
 // RUN: %target-run %t/swift-stdlib-execution
 
-// RUN: %target-interop-build-clangxx -fobjc-arc -c %t/string-to-nsstring-one-arc-op.mm -I %t -Xclang -emit-llvm -S -o - -O1 |  %FileCheck --check-prefix=CHECKARC %s
+// RUN: %target-interop-build-clangxx -std=gnu++20 -fobjc-arc -c %t/string-to-nsstring-one-arc-op.mm -I %t -Xclang -emit-llvm -S -o - -O1 |  %FileCheck --check-prefix=CHECKARC %s
 
 // REQUIRES: executable_test
 // REQUIRES: objc_interop

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

@@ -2,10 +2,20 @@
 // RUN: %target-swift-frontend -parse-as-library %platform-module-dir/Swift.swiftmodule/%module-target-triple.swiftinterface -enable-library-evolution -disable-objc-attr-requires-foundation-module -typecheck -module-name Swift -parse-stdlib -enable-experimental-cxx-interop -emit-clang-header-path %t/Swift.h  -experimental-skip-all-function-bodies
 // RUN: %FileCheck %s < %t/Swift.h
 
-// RUN: %check-interop-cxx-header-in-clang(%t/Swift.h -Wno-unused-private-field -Wno-unused-function)
+// RUN: %check-generic-interop-cxx-header-in-clang(%t/Swift.h -Wno-unused-private-field -Wno-unused-function)
 
 // CHECK: namespace Swift {
 
+// CHECK: template<class T_0_0>
+// CHECK: template<class T_0_0>
+// CHECK-NEXT: requires swift::isUsableInGenericContext<T_0_0>
+// CHECK-NEXT: class Array final {
+// CHECK-NEXT: public:
+// CHECK-NEXT: inline ~Array() {
+// CHECK: }
+// CHECK-NEXT: inline Array(const Array &other) {
+// CHECK: }
+
 // CHECK: class String final {
 // CHECK-NEXT: public:
 // CHECK-NEXT: inline ~String() {