[driver] Allow -force-single-frontend-invocation and -emit-objc-header[-path] to be used together.

Added support in Driver which allows -force-single-frontend-invocation and
-emit-objc-header[-path] to be used together in a single invocation.

Added support in tools::Swift to pass -emit-objc-header-path if an Objective-C
header was requested; this is only valid in OutputInfo::Mode::SingleCompile
mode, and an assertion enforces this.

Added a test which ensures that the same header is emitted in with
-force-single-frontend-invocation and without it.

Swift SVN r20185

include/swift/AST/DiagnosticsDriver.def

@@ -53,10 +53,6 @@ ERROR(error_command_failed,driver,none,
 ERROR(error_cannot_specify__o_for_multiple_outputs,driver,none,
       "cannot specify -o when generating multiple output files", ())
 
-ERROR(error_emit_objc_header_with_single_compile,driver,none,
-      "cannot emit an Objective-C header with "
-      "-force-single-frontend-invocation", ())
-
 ERROR(error_unable_to_load_output_file_map,driver, none,
       "unable to load output file map", ())
 

lib/Driver/Driver.cpp

@@ -416,14 +416,6 @@ void Driver::buildOutputInfo(const DerivedArgList &Args,
 
   assert(OI.CompilerOutputType != types::ID::TY_INVALID);
 
-  bool shouldEmitObjCHeader = Args.hasArg(options::OPT_emit_objc_header,
-                                          options::OPT_emit_objc_header_path);
-  if (shouldEmitObjCHeader &&
-      OI.CompilerMode == OutputInfo::Mode::SingleCompile) {
-    Diags.diagnose(SourceLoc(),
-                   diag::error_emit_objc_header_with_single_compile);
-  }
-
   OI.ShouldGenerateDebugInfo = Args.hasArg(options::OPT_g);
 
   if (Args.hasArg(options::OPT_emit_module, options::OPT_emit_module_path)) {
@@ -432,7 +424,8 @@ void Driver::buildOutputInfo(const DerivedArgList &Args,
     OI.ShouldGenerateModule = true;
     OI.ShouldTreatModuleAsTopLevelOutput = true;
   } else if ((OI.ShouldGenerateDebugInfo && OI.shouldLink()) ||
-             shouldEmitObjCHeader) {
+             Args.hasArg(options::OPT_emit_objc_header,
+                         options::OPT_emit_objc_header_path)) {
     // An option has been passed which requires a module, but the user hasn't
     // requested one. Generate a module, but treat it as an intermediate output.
     OI.ShouldGenerateModule = true;
@@ -1096,7 +1089,9 @@ Job *Driver::buildJobsForAction(const Compilation &C, const Action *A,
   }
 
   // Choose the Objective-C header output path.
-  if (isa<MergeModuleJobAction>(JA) &&
+  if ((isa<MergeModuleJobAction>(JA) ||
+       (isa<CompileJobAction>(JA) &&
+        OI.CompilerMode == OutputInfo::Mode::SingleCompile)) &&
       C.getArgs().hasArg(options::OPT_emit_objc_header,
                          options::OPT_emit_objc_header_path)) {
     StringRef ObjCHeaderPath;

lib/Driver/Tools.cpp

@@ -368,6 +368,17 @@ Job *Swift::constructJob(const JobAction &JA, std::unique_ptr<JobList> Inputs,
     Arguments.push_back(ModuleOutputPath.c_str());
   }
 
+  const std::string &ObjCHeaderOutputPath =
+    Output->getAdditionalOutputForType(types::ID::TY_ObjCHeader);
+  if (!ObjCHeaderOutputPath.empty()) {
+    assert(OI.CompilerMode == OutputInfo::Mode::SingleCompile &&
+           "The Swift tool should only emit an Obj-C header in single compile"
+           "mode!");
+
+    Arguments.push_back("-emit-objc-header-path");
+    Arguments.push_back(ObjCHeaderOutputPath.c_str());
+  }
+
   const std::string &SerializedDiagnosticsPath =
     Output->getAdditionalOutputForType(types::TY_SerializedDiagnostics);
   if (!SerializedDiagnosticsPath.empty()) {

test/Driver/Inputs/lib.swift

@@ -1,3 +1,3 @@
-// Used by multiple_input.swift test.
+// Used by multiple_input.swift and emit-objc-header.swift tests.
 
 func libraryFunction() {}

test/Driver/Inputs/main.swift

@@ -1,5 +1,5 @@
-// Used by multiple_input.swift test. This file should be inferred as the main
+// Used by multiple_input.swift and emit-objc-header.swift tests. This file
-// source file from its name.
+// should be inferred as the main source file from its name.
 
 var x = 4 + 5
 println(x)

test/Driver/emit-objc-header.swift

@@ -0,0 +1,13 @@
+// RUN: %swift_driver -Xfrontend %clang-importer-sdk -emit-module -o %t.1.swiftmodule -emit-objc-header -emit-objc-header-path %t.1.h -module-name ThisModule %s %S/Inputs/main.swift %S/Inputs/lib.swift
+// RUN: %swift_driver -Xfrontend %clang-importer-sdk -emit-module -o %t.2.swiftmodule -emit-objc-header -emit-objc-header-path %t.2.h -module-name ThisModule %s %S/Inputs/main.swift %S/Inputs/lib.swift -force-single-frontend-invocation
+// RUN: diff %t.1.h %t.2.h
+
+import Foundation
+
+public class A: NSObject {
+  func foo() {}
+  @objc func bar(x: Int, baz y: Int) -> Int { return 1 }
+}
+public class B: A {
+  func doSomething() {}
+}