[cxx-interop] add OBJC and cplusplus conditions for emitted header includes

This will allow us to generate a unified clang header.

Author: hyp

lib/PrintAsClang/PrintAsClang.cpp

@@ -13,7 +13,6 @@
 #include "swift/PrintAsClang/PrintAsClang.h"
 
 #include "ModuleContentsWriter.h"
-#include "OutputLanguageMode.h"
 
 #include "swift/AST/ASTContext.h"
 #include "swift/AST/Module.h"
@@ -28,7 +27,28 @@
 using namespace swift;
 
 static void writePrologue(raw_ostream &out, ASTContext &ctx,
-                          StringRef macroGuard, OutputLanguageMode Lang) {
+                          StringRef macroGuard) {
+  auto emitCxxConditional = [&](llvm::function_ref<void()> cxxCase,
+                                llvm::function_ref<void()> cCase = {}) {
+    out << "#if defined(__cplusplus)\n";
+    cxxCase();
+    if (cCase) {
+      out << "#else\n";
+      cCase();
+    }
+    out << "#endif\n";
+  };
+  auto emitObjCConditional = [&](llvm::function_ref<void()> objcCase,
+                                 llvm::function_ref<void()> nonObjCCase = {}) {
+    out << "#if defined(__OBJC__)\n";
+    objcCase();
+    if (nonObjCCase) {
+      out << "#else\n";
+      nonObjCCase();
+    }
+    out << "#endif\n";
+  };
+
   out << "// Generated by "
       << version::getSwiftFullVersion(ctx.LangOpts.EffectiveLanguageVersion)
       << "\n"
@@ -57,16 +77,18 @@ static void writePrologue(raw_ostream &out, ASTContext &ctx,
          "#endif\n"
          "\n"
          "#pragma clang diagnostic ignored \"-Wauto-import\"\n";
-  if (Lang == OutputLanguageMode::Cxx) {
-    out << "#include <cstdint>\n"
-           "#include <cstddef>\n"
-           "#include <cstdbool>\n";
-  } else {
-    out << "#include <Foundation/Foundation.h>\n"
-           "#include <stdint.h>\n"
-           "#include <stddef.h>\n"
-           "#include <stdbool.h>\n";
-  }
+  emitObjCConditional([&] { out << "#include <Foundation/Foundation.h>\n"; });
+  emitCxxConditional(
+      [&] {
+        out << "#include <cstdint>\n"
+               "#include <cstddef>\n"
+               "#include <cstdbool>\n";
+      },
+      [&] {
+        out << "#include <stdint.h>\n"
+               "#include <stddef.h>\n"
+               "#include <stdbool.h>\n";
+      });
   out << "\n"
          "#if !defined(SWIFT_TYPEDEFS)\n"
          "# define SWIFT_TYPEDEFS 1\n"
@@ -254,30 +276,27 @@ static void writePrologue(raw_ostream &out, ASTContext &ctx,
          "#else\n"
          "# define SWIFT_DEPRECATED_OBJC(Msg) SWIFT_DEPRECATED_MSG(Msg)\n"
          "#endif\n";
-  if (Lang == OutputLanguageMode::ObjC) {
+  emitObjCConditional([&] {
     out << "#if !defined(IBSegueAction)\n"
            "# define IBSegueAction\n"
            "#endif\n";
-  }
+  });
   out << "#if !defined(SWIFT_EXTERN)\n"
          "# if defined(__cplusplus)\n"
          "#  define SWIFT_EXTERN extern \"C\"\n"
          "# else\n"
          "#  define SWIFT_EXTERN extern\n"
          "# endif\n"
          "#endif\n";
-  auto emitMacro = [&](StringRef name, StringRef value) {
+  auto emitMacro = [&](StringRef name, StringRef value = "") {
     out << "#if !defined(" << name << ")\n";
     out << "# define " << name << " " << value << "\n";
     out << "#endif\n";
   };
   emitMacro("SWIFT_CALL", "__attribute__((swiftcall))");
   // SWIFT_NOEXCEPT applies 'noexcept' in C++ mode only.
-  out << "#if defined(__cplusplus)\n";
-  emitMacro("SWIFT_NOEXCEPT", "noexcept");
-  out << "#else\n";
-  emitMacro("SWIFT_NOEXCEPT", "");
-  out << "#endif\n";
+  emitCxxConditional([&] { emitMacro("SWIFT_NOEXCEPT", "noexcept"); },
+                     [&] { emitMacro("SWIFT_NOEXCEPT"); });
   static_assert(SWIFT_MAX_IMPORTED_SIMD_ELEMENTS == 4,
               "need to add SIMD typedefs here if max elements is increased");
 }
@@ -431,8 +450,7 @@ bool swift::printAsObjC(raw_ostream &os, ModuleDecl *M,
   std::string moduleContentsBuf;
   llvm::raw_string_ostream moduleContents{moduleContentsBuf};
   printModuleContentsAsObjC(moduleContents, imports, *M);
-  writePrologue(os, M->getASTContext(), computeMacroGuard(M),
-                OutputLanguageMode::ObjC);
+  writePrologue(os, M->getASTContext(), computeMacroGuard(M));
   writeImports(os, imports, *M, bridgingHeader);
   writePostImportPrologue(os, *M);
   os << moduleContents.str();
@@ -448,8 +466,7 @@ bool swift::printAsCXX(raw_ostream &os, ModuleDecl *M) {
   std::string moduleContentsBuf;
   llvm::raw_string_ostream moduleContents{moduleContentsBuf};
   printModuleContentsAsCxx(moduleContents, imports, *M);
-  writePrologue(os, M->getASTContext(), computeMacroGuard(M),
-                OutputLanguageMode::Cxx);
+  writePrologue(os, M->getASTContext(), computeMacroGuard(M));
   writePostImportPrologue(os, *M);
   os << moduleContents.str();
   writeEpilogue(os);

test/PrintAsCxx/empty.swift

@@ -27,9 +27,18 @@
 // CHECK-NEXT: # define __has_warning(x) 0
 // CHECK-NEXT: #endif
 
-// CHECK-LABEL: #include <cstdint>
-// CHECK: #include <cstddef>
-// CHECK: #include <cstdbool>
+// CHECK-LABEL: #if defined(__OBJC__)
+// CHECK-NEXT:  #include <Foundation/Foundation.h>
+// CHECK-NEXT:  #endif
+// CHECK-NEXT:  #if defined(__cplusplus)
+// CHECK-NEXT:  #include <cstdint>
+// CHECK-NEXT:  #include <cstddef>
+// CHECK-NEXT:  #include <cstdbool>
+// CHECK-NEXT:  #else
+// CHECK-NEXT:  #include <stdint.h>
+// CHECK-NEXT:  #include <stddef.h>
+// CHECK-NEXT:  #include <stdbool.h>
+// CHECK-NEXT:  #endif
 
 // CHECK-LABEL: !defined(SWIFT_TYPEDEFS)
 // CHECK-NEXT:  # define SWIFT_TYPEDEFS 1