Merge pull request swiftlang#40923 from hyp/emit-cxx-interface-option

hyp · web-flow · commit e0eec4dd7c76 · 2022-01-20T07:16:53.000-08:00
[interop] add an option to emit C++ header interface for a module
diff --git a/include/swift/AST/DiagnosticsFrontend.def b/include/swift/AST/DiagnosticsFrontend.def
@@ -119,6 +119,8 @@ ERROR(error_mode_cannot_emit_reference_dependencies,none,
       "this mode does not support emitting reference dependency files", ())
 ERROR(error_mode_cannot_emit_header,none,
       "this mode does not support emitting Objective-C headers", ())
+ERROR(error_mode_cannot_emit_cxx_header,none,
+      "this mode does not support emitting C++ headers", ())
 ERROR(error_mode_cannot_emit_loaded_module_trace,none,
       "this mode does not support emitting the loaded module trace", ())
 ERROR(error_mode_cannot_emit_module,none,
diff --git a/include/swift/Basic/SupplementaryOutputPaths.h b/include/swift/Basic/SupplementaryOutputPaths.h
@@ -31,6 +31,17 @@ struct SupplementaryOutputPaths {
   /// \sa swift::printAsObjC
   std::string ObjCHeaderOutputPath;
 
+  /// The path to which we should emit a C++ header for the module.
+  ///
+  /// Currently only makes sense when the compiler has whole module knowledge.
+  /// The modes for which it makes sense include both WMO and the "merge
+  /// modules" job that happens after the normal compilation jobs. That's where
+  /// the header is emitted in single-file mode, since it needs whole-module
+  /// information.
+  ///
+  /// \sa swift::printAsCxx
+  std::string CxxHeaderOutputPath;
+
   /// The path to which we should emit a serialized module.
   /// It is valid whenever there are any inputs.
   ///
@@ -160,7 +171,9 @@ struct SupplementaryOutputPaths {
   /// Apply a given function for each existing (non-empty string) supplementary output
   void forEachSetOutput(llvm::function_ref<void(const std::string&)> fn) const {
     if (!ObjCHeaderOutputPath.empty())
-      fn(ObjCHeaderOutputPath); 
+      fn(ObjCHeaderOutputPath);
+    if (!CxxHeaderOutputPath.empty())
+      fn(CxxHeaderOutputPath);
     if (!ModuleOutputPath.empty())
       fn(ModuleOutputPath); 
     if (!ModuleSourceInfoOutputPath.empty())
@@ -196,14 +209,16 @@ struct SupplementaryOutputPaths {
   }
 
   bool empty() const {
-    return ObjCHeaderOutputPath.empty() && ModuleOutputPath.empty() &&
-           ModuleDocOutputPath.empty() && DependenciesFilePath.empty() &&
+    return ObjCHeaderOutputPath.empty() && CxxHeaderOutputPath.empty() &&
+           ModuleOutputPath.empty() && ModuleDocOutputPath.empty() &&
+           DependenciesFilePath.empty() &&
            ReferenceDependenciesFilePath.empty() &&
            SerializedDiagnosticsPath.empty() && LoadedModuleTracePath.empty() &&
            TBDPath.empty() && ModuleInterfaceOutputPath.empty() &&
-           ModuleSourceInfoOutputPath.empty() && ABIDescriptorOutputPath.empty() &&
-           ModuleSemanticInfoOutputPath.empty() &&
-           YAMLOptRecordPath.empty() && BitstreamOptRecordPath.empty();
+           ModuleSourceInfoOutputPath.empty() &&
+           ABIDescriptorOutputPath.empty() &&
+           ModuleSemanticInfoOutputPath.empty() && YAMLOptRecordPath.empty() &&
+           BitstreamOptRecordPath.empty();
   }
 };
 } // namespace swift
diff --git a/include/swift/Frontend/Frontend.h b/include/swift/Frontend/Frontend.h
@@ -388,6 +388,7 @@ class CompilerInvocation {
   std::string getOutputFilenameForAtMostOnePrimary() const;
   std::string getMainInputFilenameForDebugInfoForAtMostOnePrimary() const;
   std::string getObjCHeaderOutputPathForAtMostOnePrimary() const;
+  std::string getCxxHeaderOutputPathForAtMostOnePrimary() const;
   std::string getModuleOutputPathForAtMostOnePrimary() const;
   std::string
   getReferenceDependenciesFilePathForPrimary(StringRef filename) const;
diff --git a/include/swift/Frontend/FrontendInputsAndOutputs.h b/include/swift/Frontend/FrontendInputsAndOutputs.h
@@ -250,6 +250,7 @@ class FrontendInputsAndOutputs {
   bool hasDependenciesPath() const;
   bool hasReferenceDependenciesPath() const;
   bool hasObjCHeaderOutputPath() const;
+  bool hasCxxHeaderOutputPath() const;
   bool hasLoadedModuleTracePath() const;
   bool hasModuleOutputPath() const;
   bool hasModuleDocOutputPath() const;
diff --git a/include/swift/Frontend/FrontendOptions.h b/include/swift/Frontend/FrontendOptions.h
@@ -450,7 +450,7 @@ class FrontendOptions {
 private:
   static bool canActionEmitDependencies(ActionType);
   static bool canActionEmitReferenceDependencies(ActionType);
-  static bool canActionEmitObjCHeader(ActionType);
+  static bool canActionEmitClangHeader(ActionType);
   static bool canActionEmitLoadedModuleTrace(ActionType);
   static bool canActionEmitModule(ActionType);
   static bool canActionEmitModuleDoc(ActionType);
diff --git a/include/swift/Option/Options.td b/include/swift/Option/Options.td
@@ -532,6 +532,14 @@ def emit_objc_header_path : Separate<["-"], "emit-objc-header-path">,
          SupplementaryOutput]>,
   MetaVarName<"<path>">, HelpText<"Emit an Objective-C header file to <path>">;
 
+def emit_cxx_header : Flag<["-"], "emit-cxx-header">,
+  Flags<[FrontendOption, NoInteractiveOption, SupplementaryOutput]>,
+  HelpText<"Emit a C++ header file">;
+def emit_cxx_header_path : Separate<["-"], "emit-cxx-header-path">,
+  Flags<[FrontendOption, NoInteractiveOption, ArgumentIsPath,
+         SupplementaryOutput]>,
+  MetaVarName<"<path>">, HelpText<"Emit a C++ header file to <path>">;
+
 def static : Flag<["-"], "static">,
   Flags<[FrontendOption, ModuleInterfaceOption, NoInteractiveOption]>,
   HelpText<"Make this module statically linkable and make the output of -emit-library a static library.">;
diff --git a/include/swift/PrintAsObjC/PrintAsObjC.h b/include/swift/PrintAsObjC/PrintAsObjC.h
@@ -26,6 +26,11 @@ namespace swift {
   ///
   /// Returns true on error.
   bool printAsObjC(raw_ostream &out, ModuleDecl *M, StringRef bridgingHeader);
+
+  /// Print the C++-compatible declarations in a module as a Clang header.
+  ///
+  /// Returns true on error.
+  bool printAsCXX(raw_ostream &os, ModuleDecl *M);
 }
 
 #endif
diff --git a/lib/Frontend/ArgsToFrontendOptionsConverter.cpp b/lib/Frontend/ArgsToFrontendOptionsConverter.cpp
@@ -623,11 +623,16 @@ bool ArgsToFrontendOptionsConverter::checkUnusedSupplementaryOutputPaths()
                    diag::error_mode_cannot_emit_reference_dependencies);
     return true;
   }
-  if (!FrontendOptions::canActionEmitObjCHeader(Opts.RequestedAction) &&
+  if (!FrontendOptions::canActionEmitClangHeader(Opts.RequestedAction) &&
       Opts.InputsAndOutputs.hasObjCHeaderOutputPath()) {
     Diags.diagnose(SourceLoc(), diag::error_mode_cannot_emit_header);
     return true;
   }
+  if (!FrontendOptions::canActionEmitClangHeader(Opts.RequestedAction) &&
+      Opts.InputsAndOutputs.hasCxxHeaderOutputPath()) {
+    Diags.diagnose(SourceLoc(), diag::error_mode_cannot_emit_cxx_header);
+    return true;
+  }
   if (!FrontendOptions::canActionEmitLoadedModuleTrace(Opts.RequestedAction) &&
       Opts.InputsAndOutputs.hasLoadedModuleTracePath()) {
     Diags.diagnose(SourceLoc(),
diff --git a/lib/Frontend/ArgsToFrontendOutputsConverter.cpp b/lib/Frontend/ArgsToFrontendOutputsConverter.cpp
@@ -310,6 +310,8 @@ SupplementaryOutputPathsComputer::getSupplementaryOutputPathsFromArguments()
 
   auto objCHeaderOutput = getSupplementaryFilenamesFromArguments(
       options::OPT_emit_objc_header_path);
+  auto cxxHeaderOutput =
+      getSupplementaryFilenamesFromArguments(options::OPT_emit_cxx_header_path);
   auto moduleOutput =
       getSupplementaryFilenamesFromArguments(options::OPT_emit_module_path);
   auto moduleDocOutput =
@@ -339,8 +341,8 @@ SupplementaryOutputPathsComputer::getSupplementaryOutputPathsFromArguments()
       options::OPT_emit_module_semantic_info_path);
   auto optRecordOutput = getSupplementaryFilenamesFromArguments(
       options::OPT_save_optimization_record_path);
-  if (!objCHeaderOutput || !moduleOutput || !moduleDocOutput ||
-      !dependenciesFile || !referenceDependenciesFile ||
+  if (!objCHeaderOutput || !cxxHeaderOutput || !moduleOutput ||
+      !moduleDocOutput || !dependenciesFile || !referenceDependenciesFile ||
       !serializedDiagnostics || !fixItsOutput || !loadedModuleTrace || !TBD ||
       !moduleInterfaceOutput || !privateModuleInterfaceOutput ||
       !moduleSourceInfoOutput || !moduleSummaryOutput || !abiDescriptorOutput ||
@@ -354,6 +356,7 @@ SupplementaryOutputPathsComputer::getSupplementaryOutputPathsFromArguments()
   for (unsigned i = 0; i < N; ++i) {
     SupplementaryOutputPaths sop;
     sop.ObjCHeaderOutputPath = (*objCHeaderOutput)[i];
+    sop.CxxHeaderOutputPath = (*cxxHeaderOutput)[i];
     sop.ModuleOutputPath = (*moduleOutput)[i];
     sop.ModuleDocOutputPath = (*moduleDocOutput)[i];
     sop.DependenciesFilePath = (*dependenciesFile)[i];
@@ -439,6 +442,11 @@ SupplementaryOutputPathsComputer::computeOutputPathsForOneInput(
       file_types::TY_ObjCHeader, "",
       defaultSupplementaryOutputPathExcludingExtension);
 
+  auto cxxHeaderOutputPath = determineSupplementaryOutputFilename(
+      OPT_emit_cxx_header, pathsFromArguments.CxxHeaderOutputPath,
+      file_types::TY_ObjCHeader, "",
+      defaultSupplementaryOutputPathExcludingExtension);
+
   auto loadedModuleTracePath = determineSupplementaryOutputFilename(
       OPT_emit_loaded_module_trace, pathsFromArguments.LoadedModuleTracePath,
       file_types::TY_ModuleTrace, "",
@@ -493,6 +501,7 @@ SupplementaryOutputPathsComputer::computeOutputPathsForOneInput(
 
   SupplementaryOutputPaths sop;
   sop.ObjCHeaderOutputPath = objcHeaderOutputPath;
+  sop.CxxHeaderOutputPath = cxxHeaderOutputPath;
   sop.ModuleOutputPath = moduleOutputPath;
   sop.ModuleDocOutputPath = moduleDocOutputPath;
   sop.DependenciesFilePath = dependenciesFilePath;
@@ -578,6 +587,7 @@ createFromTypeToPathMap(const TypeToPathMap *map) {
     return paths;
   const std::pair<file_types::ID, std::string &> typesAndStrings[] = {
       {file_types::TY_ObjCHeader, paths.ObjCHeaderOutputPath},
+      {file_types::TY_ObjCHeader, paths.CxxHeaderOutputPath},
       {file_types::TY_SwiftModuleFile, paths.ModuleOutputPath},
       {file_types::TY_SwiftModuleDocFile, paths.ModuleDocOutputPath},
       {file_types::TY_SwiftSourceInfoFile, paths.ModuleSourceInfoOutputPath},
@@ -606,17 +616,16 @@ createFromTypeToPathMap(const TypeToPathMap *map) {
 Optional<std::vector<SupplementaryOutputPaths>>
 SupplementaryOutputPathsComputer::readSupplementaryOutputFileMap() const {
   if (Arg *A = Args.getLastArg(
-        options::OPT_emit_objc_header_path,
-        options::OPT_emit_module_path,
-        options::OPT_emit_module_doc_path,
-        options::OPT_emit_dependencies_path,
-        options::OPT_emit_reference_dependencies_path,
-        options::OPT_serialize_diagnostics_path,
-        options::OPT_emit_loaded_module_trace_path,
-        options::OPT_emit_module_interface_path,
-        options::OPT_emit_private_module_interface_path,
-        options::OPT_emit_module_source_info_path,
-        options::OPT_emit_tbd_path)) {
+          options::OPT_emit_objc_header_path, options::OPT_emit_cxx_header_path,
+          options::OPT_emit_module_path, options::OPT_emit_module_doc_path,
+          options::OPT_emit_dependencies_path,
+          options::OPT_emit_reference_dependencies_path,
+          options::OPT_serialize_diagnostics_path,
+          options::OPT_emit_loaded_module_trace_path,
+          options::OPT_emit_module_interface_path,
+          options::OPT_emit_private_module_interface_path,
+          options::OPT_emit_module_source_info_path,
+          options::OPT_emit_tbd_path)) {
     Diags.diagnose(SourceLoc(),
                    diag::error_cannot_have_supplementary_outputs,
                    A->getSpelling(), "-supplementary-output-file-map");
diff --git a/lib/Frontend/Frontend.cpp b/lib/Frontend/Frontend.cpp
@@ -96,6 +96,11 @@ CompilerInvocation::getObjCHeaderOutputPathForAtMostOnePrimary() const {
   return getPrimarySpecificPathsForAtMostOnePrimary()
       .SupplementaryOutputs.ObjCHeaderOutputPath;
 }
+std::string
+CompilerInvocation::getCxxHeaderOutputPathForAtMostOnePrimary() const {
+  return getPrimarySpecificPathsForAtMostOnePrimary()
+      .SupplementaryOutputs.CxxHeaderOutputPath;
+}
 std::string CompilerInvocation::getModuleOutputPathForAtMostOnePrimary() const {
   return getPrimarySpecificPathsForAtMostOnePrimary()
       .SupplementaryOutputs.ModuleOutputPath;
diff --git a/lib/Frontend/FrontendInputsAndOutputs.cpp b/lib/Frontend/FrontendInputsAndOutputs.cpp
@@ -467,6 +467,12 @@ bool FrontendInputsAndOutputs::hasObjCHeaderOutputPath() const {
         return outs.ObjCHeaderOutputPath;
       });
 }
+bool FrontendInputsAndOutputs::hasCxxHeaderOutputPath() const {
+  return hasSupplementaryOutputPath(
+      [](const SupplementaryOutputPaths &outs) -> const std::string & {
+        return outs.CxxHeaderOutputPath;
+      });
+}
 bool FrontendInputsAndOutputs::hasLoadedModuleTracePath() const {
   return hasSupplementaryOutputPath(
       [](const SupplementaryOutputPaths &outs) -> const std::string & {
diff --git a/lib/Frontend/FrontendOptions.cpp b/lib/Frontend/FrontendOptions.cpp
@@ -231,12 +231,11 @@ void FrontendOptions::forAllOutputPaths(
   }
   const SupplementaryOutputPaths &outs =
       input.getPrimarySpecificPaths().SupplementaryOutputs;
-  const std::string *outputs[] = {&outs.ModuleOutputPath,
-                                  &outs.ModuleDocOutputPath,
-                                  &outs.ModuleInterfaceOutputPath,
-                                  &outs.PrivateModuleInterfaceOutputPath,
-                                  &outs.ObjCHeaderOutputPath,
-                                  &outs.ModuleSourceInfoOutputPath};
+  const std::string *outputs[] = {
+      &outs.ModuleOutputPath,          &outs.ModuleDocOutputPath,
+      &outs.ModuleInterfaceOutputPath, &outs.PrivateModuleInterfaceOutputPath,
+      &outs.ObjCHeaderOutputPath,      &outs.CxxHeaderOutputPath,
+      &outs.ModuleSourceInfoOutputPath};
   for (const std::string *next : outputs) {
     if (!next->empty())
       fn(*next);
@@ -449,7 +448,7 @@ bool FrontendOptions::canActionEmitModuleSummary(ActionType action) {
   llvm_unreachable("unhandled action");
 }
 
-bool FrontendOptions::canActionEmitObjCHeader(ActionType action) {
+bool FrontendOptions::canActionEmitClangHeader(ActionType action) {
   switch (action) {
   case ActionType::NoneAction:
   case ActionType::Parse:
diff --git a/lib/FrontendTool/FrontendTool.cpp b/lib/FrontendTool/FrontendTool.cpp
@@ -186,6 +186,22 @@ static bool printAsObjCIfNeeded(StringRef outputPath, ModuleDecl *M,
   });
 }
 
+/// Prints the C++  "generated header" interface for \p M to \p
+/// outputPath.
+///
+/// ...unless \p outputPath is empty, in which case it does nothing.
+///
+/// \returns true if there were any errors
+///
+/// \see swift::printAsCxx
+static bool printAsCxxIfNeeded(StringRef outputPath, ModuleDecl *M) {
+  if (outputPath.empty())
+    return false;
+  return withOutputFile(
+      M->getDiags(), outputPath,
+      [&](raw_ostream &os) -> bool { return printAsCXX(os, M); });
+}
+
 /// Prints the stable module interface for \p M to \p outputPath.
 ///
 /// ...unless \p outputPath is empty, in which case it does nothing.
@@ -826,6 +842,12 @@ static bool emitAnyWholeModulePostTypeCheckSupplementaryOutputs(
         Invocation.getObjCHeaderOutputPathForAtMostOnePrimary(),
         Instance.getMainModule(), BridgingHeaderPathForPrint);
   }
+  if ((!Context.hadError() || opts.AllowModuleWithCompilerErrors) &&
+      opts.InputsAndOutputs.hasCxxHeaderOutputPath()) {
+    hadAnyError |= printAsCxxIfNeeded(
+        Invocation.getCxxHeaderOutputPathForAtMostOnePrimary(),
+        Instance.getMainModule());
+  }
 
   // Only want the header if there's been any errors, ie. there's not much
   // point outputting a swiftinterface for an invalid module
diff --git a/lib/PrintAsObjC/PrintAsObjC.cpp b/lib/PrintAsObjC/PrintAsObjC.cpp
@@ -389,6 +389,10 @@ static void writeEpilogue(raw_ostream &os) {
       "#endif\n";
 }
 
+static std::string computeMacroGuard(const ModuleDecl *M) {
+  return (llvm::Twine(M->getNameStr().upper()) + "_SWIFT_H").str();
+}
+
 bool swift::printAsObjC(raw_ostream &os, ModuleDecl *M,
                         StringRef bridgingHeader) {
   llvm::PrettyStackTraceString trace("While generating Objective-C header");
@@ -397,12 +401,22 @@ bool swift::printAsObjC(raw_ostream &os, ModuleDecl *M,
   std::string moduleContentsBuf;
   llvm::raw_string_ostream moduleContents{moduleContentsBuf};
   printModuleContentsAsObjC(moduleContents, imports, *M);
-  std::string macroGuard = (llvm::Twine(M->getNameStr().upper()) + "_SWIFT_H").str();
-  writePrologue(os, M->getASTContext(), macroGuard);
+  writePrologue(os, M->getASTContext(), computeMacroGuard(M));
   writeImports(os, imports, *M, bridgingHeader);
   writePostImportPrologue(os, *M);
   os << moduleContents.str();
   writeEpilogue(os);
 
   return false;
 }
+
+bool swift::printAsCXX(raw_ostream &os, ModuleDecl *M) {
+  llvm::PrettyStackTraceString trace("While generating C++ header");
+
+  writePrologue(os, M->getASTContext(), computeMacroGuard(M));
+  writePostImportPrologue(os, *M);
+  // TODO (Alex): emit module contents.
+  writeEpilogue(os);
+
+  return false;
+}
diff --git a/test/Frontend/supplementary-output-support.swift b/test/Frontend/supplementary-output-support.swift
@@ -24,6 +24,13 @@
 // RUN: not %target-swift-frontend -resolve-imports -emit-objc-header %s 2>&1 | %FileCheck -check-prefix=RESOLVE_IMPORTS_NO_OBJC_HEADER %s
 // RESOLVE_IMPORTS_NO_OBJC_HEADER: error: this mode does not support emitting Objective-C headers{{$}}
 
+// RUN: not %target-swift-frontend -parse -emit-cxx-header %s 2>&1 | %FileCheck -check-prefix=PARSE_NO_CXX_HEADER %s
+// PARSE_NO_CXX_HEADER: error: this mode does not support emitting C++ headers{{$}}
+// RUN: not %target-swift-frontend -dump-ast -emit-cxx-header %s 2>&1 | %FileCheck -check-prefix=DUMP_NO_CXX_HEADER %s
+// DUMP_NO_CXX_HEADER: error: this mode does not support emitting C++ headers{{$}}
+// RUN: not %target-swift-frontend -resolve-imports -emit-cxx-header %s 2>&1 | %FileCheck -check-prefix=RESOLVE_IMPORTS_NO_CXX_HEADER %s
+// RESOLVE_IMPORTS_NO_CXX_HEADER: error: this mode does not support emitting C++ headers{{$}}
+
 // RUN: not %target-swift-frontend -parse -emit-module-interface-path %t %s 2>&1 | %FileCheck -check-prefix=PARSE_NO_INTERFACE %s
 // PARSE_NO_INTERFACE: error: this mode does not support emitting module interface files{{$}}
 // RUN: not %target-swift-frontend -emit-silgen -emit-module-interface-path %t %s 2>&1 | %FileCheck -check-prefix=SILGEN_NO_INTERFACE %s
diff --git a/test/PrintAsCxx/empty.swift b/test/PrintAsCxx/empty.swift
