From d81557a01fc841ecf798a2f134668c04a3cc7d70 Mon Sep 17 00:00:00 2001
From: Alex Lorenz <arphaman@gmail.com>
Date: Thu, 4 May 2023 10:34:12 -0700
Subject: [PATCH] [interop][SwiftToCxx] remove extraneous semicolon when
 emitting 'pragma clang module import'

The semicolon actually causes a compiler error in that case

(cherry picked from commit 228078f074760215a799d363dea5e0adf05eacfd)
---
 lib/PrintAsClang/PrintAsClang.cpp                   |  6 +++---
 .../bridge-cxx-struct-back-to-cxx.swift             |  7 +++++--
 .../bridge-cxx-struct-back-to-objcxx.swift          | 13 +++++++++++++
 3 files changed, 21 insertions(+), 5 deletions(-)
 create mode 100644 test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-objcxx.swift

diff --git a/lib/PrintAsClang/PrintAsClang.cpp b/lib/PrintAsClang/PrintAsClang.cpp
index ed3bacf10448a..278a4af50373d 100644
--- a/lib/PrintAsClang/PrintAsClang.cpp
+++ b/lib/PrintAsClang/PrintAsClang.cpp
@@ -448,6 +448,7 @@ writeImports(raw_ostream &out, llvm::SmallPtrSetImpl<ImportModuleTy> &imports,
   bool includeUnderlying = false;
   StringRef importDirective =
       useCxxImport ? "#pragma clang module import" : "@import";
+  StringRef importDirectiveLineEnd = useCxxImport ? "\n" : ";\n";
   for (auto import : sortedImports) {
     if (auto *swiftModule = import.dyn_cast<ModuleDecl *>()) {
       if (useCxxImport) {
@@ -464,7 +465,7 @@ writeImports(raw_ostream &out, llvm::SmallPtrSetImpl<ImportModuleTy> &imports,
         continue;
       }
       if (seenImports.insert(Name).second) {
-        out << importDirective << ' ' << Name.str() << ";\n";
+        out << importDirective << ' ' << Name.str() << importDirectiveLineEnd;
         if (frontendOpts.EmitClangHeaderWithNonModularIncludes) {
           if (const clang::Module *underlyingClangModule =
                   swiftModule->findUnderlyingClangModule()) {
@@ -487,8 +488,7 @@ writeImports(raw_ostream &out, llvm::SmallPtrSetImpl<ImportModuleTy> &imports,
              "top-level modules should use a normal swift::ModuleDecl");
       out << importDirective << ' ';
       ModuleDecl::ReverseFullNameIterator(clangModule).printForward(out);
-      out << ";\n";
-
+      out << importDirectiveLineEnd;
       if (frontendOpts.EmitClangHeaderWithNonModularIncludes) {
         collectClangModuleHeaderIncludes(
             clangModule, fileManager, requiredTextualIncludes, visitedModules,
diff --git a/test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-cxx.swift b/test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-cxx.swift
index 259bf9fd8099d..550885c073905 100644
--- a/test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-cxx.swift
+++ b/test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-cxx.swift
@@ -15,7 +15,10 @@
 
 // RUN: %check-interop-cxx-header-in-clang(%t/full-cxx-swift-cxx-bridging.h -Wno-reserved-identifier)
 
-// FIXME: test in C++ with modules (but libc++ modularization is preventing this)
+// Check that the generated header can be
+// built with Clang modules enabled in C++.
+
+// RUN: %target-interop-build-clangxx -fsyntax-only -x c++-header %t/full-cxx-swift-cxx-bridging.h -std=gnu++20 -c -fmodules -fcxx-modules -I %t
 
 //--- header.h
 
@@ -149,7 +152,7 @@ public func takeTrivialInout(_ x: inout Trivial) {
 // CHECK-NEXT: #if __has_warning("-Watimport-in-framework-header")
 // CHECK-NEXT: #pragma clang diagnostic ignored "-Watimport-in-framework-header"
 // CHECK-NEXT:#endif
-// CHECK-NEXT: #pragma clang module import CxxTest;
+// CHECK-NEXT: #pragma clang module import CxxTest
 // CHECK-NEXT: #endif
 
 
diff --git a/test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-objcxx.swift b/test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-objcxx.swift
new file mode 100644
index 0000000000000..09893eb82badc
--- /dev/null
+++ b/test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-objcxx.swift
@@ -0,0 +1,13 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %S/bridge-cxx-struct-back-to-cxx.swift %t
+
+// RUN: %target-swift-frontend -typecheck %t/use-cxx-types.swift -typecheck -module-name UseCxxTy -emit-clang-header-path %t/UseCxxTy.h -I %t -enable-experimental-cxx-interop -clang-header-expose-decls=all-public -disable-availability-checking
+// RUN: echo "#include \"header.h\"" > %t/full-cxx-swift-cxx-bridging.h
+// RUN: cat %t/UseCxxTy.h >> %t/full-cxx-swift-cxx-bridging.h
+
+// Check that the generated header can be
+// built with Clang modules enabled in ObjC++.
+
+// REQUIRES: objc_interop
+
+// RUN: %target-interop-build-clangxx -fsyntax-only -x objective-c++-header %t/full-cxx-swift-cxx-bridging.h -std=gnu++20 -c -fmodules -fcxx-modules -I %t