Merge pull request #61417 from hyp/eng/stdlib-guard

[interop][SwiftToCxx] guard inline emitted Stdlib module

Author: hyp

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -773,7 +773,10 @@ EmittedClangHeaderDependencyInfo swift::printModuleContentsAsCxx(
 
   // FIXME: refactor.
   if (!prologueOS.str().empty()) {
-    os << "#endif\n";
+    // FIXME: This is a workaround for prologue being emitted outside of
+    // __cplusplus.
+    if (!M.isStdlibModule())
+      os << "#endif\n";
     os << "#ifdef __cplusplus\n";
     os << "namespace ";
     M.ValueDecl::getName().print(os);
@@ -784,7 +787,8 @@ EmittedClangHeaderDependencyInfo swift::printModuleContentsAsCxx(
 
     os << prologueOS.str();
 
-    os << "\n#ifdef __cplusplus\n";
+    if (!M.isStdlibModule())
+      os << "\n#ifdef __cplusplus\n";
     os << "}\n";
     os << "}\n";
     os << "}\n";

lib/PrintAsClang/PrintAsClang.cpp

@@ -528,7 +528,12 @@ bool swift::printAsClangHeader(raw_ostream &os, ModuleDecl *M,
       if (defaultDependencyBehavior && deps.dependsOnStandardLibrary) {
         assert(!M->isStdlibModule());
         SwiftToClangInteropContext interopContext(*M->getASTContext().getStdlibModule(), irGenOpts);
+        auto macroGuard =
+            computeMacroGuard(M->getASTContext().getStdlibModule());
+        os << "#ifndef " << macroGuard << "\n";
+        os << "#define " << macroGuard << "\n";
         printModuleContentsAsCxx(os, *M->getASTContext().getStdlibModule(), interopContext, /*requiresExposedAttribute=*/true);
+        os << "#endif // " << macroGuard << "\n";
       }
 
       os << moduleContents.str();

lib/PrintAsClang/experimental-interoperability-version.json

@@ -1 +1 @@
-2
+3

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

@@ -1,9 +1,14 @@
 // RUN: %empty-directory(%t)
 
 // RUN: %target-swift-frontend -typecheck %s -typecheck -module-name UseOptional -enable-experimental-cxx-interop -emit-clang-header-path %t/stdlib.h
+// RUN: %target-swift-frontend -typecheck %s -typecheck -module-name UseOptional2 -enable-experimental-cxx-interop -emit-clang-header-path %t/stdlib2.h
 
 // RUN: %FileCheck %s < %t/stdlib.h
 
+// RUN: cat %t/stdlib.h %t/stdlib2.h > %t/two_includes.h
+
+// RUN: %check-generic-interop-cxx-header-in-clang(%t/two_includes.h -Wno-unused-private-field -Wno-unused-function -Wno-shadow -Wno-documentation)
+
 @_expose(Cxx)
 public func test() -> String {
     return ""