Support enum forward decls in Objective C++

NS_ENUM changes defintion in Objective C++ based on the C++ spec being
compiled with, special case the one situation where it wouldn't support doing a
forward decl for the enum.

4 files changed, 91 insertions, 6 deletions

diff --git a/objectivec/GPBBootstrap.h b/objectivec/GPBBootstrap.h
index 3dd2de83..c49c7e20 100644
--- a/objectivec/GPBBootstrap.h
+++ b/objectivec/GPBBootstrap.h
@@ -46,12 +46,20 @@
 
 // Used in the generated code to give sizes to enums. int32_t was chosen based
 // on the fact that Protocol Buffers enums are limited to this range.
-// The complexity and double definition here are so we get the nice name
-// for objective C, but also define the name with a trailing underscore so
-// the Swift bridge will have one where the names line up to support short
-// names since they are scoped to the enum.
-// https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/InteractingWithCAPIs.html#//apple_ref/doc/uid/TP40014216-CH8-XID_11
-#define GPB_ENUM(X) NS_ENUM(int32_t, X)
+#if !__has_feature(objc_fixed_enum)
+ #error All supported Xcode versions should support objc_fixed_enum.
+#endif
+// If the headers are imported into Objective-C++, we can run into an issue
+// where the defintion of NS_ENUM (really CF_ENUM) changes based on the C++
+// standard that is in effect.  If it isn't C++11 or higher, the definition
+// doesn't allow us to forward declare. We work around this one case by
+// providing a local definition. The default case has to use NS_ENUM for the
+// magic that is Swift bridging of enums.
+#if (__cplusplus && __cplusplus < 201103L)
+ #define GPB_ENUM(X) enum X : int32_t X; enum X : int32_t
+#else
+ #define GPB_ENUM(X) NS_ENUM(int32_t, X)
+#endif
 // GPB_ENUM_FWD_DECLARE is used for forward declaring enums, ex:
 //   GPB_ENUM_FWD_DECLARE(Foo_Enum)
 //   @property (nonatomic) Foo_Enum value;
diff --git a/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj b/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
index b0a0712e..08d0b7ef 100644
--- a/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
+++ b/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
@@ -58,6 +58,7 @@
 		F4487C831AAF6AB300531423 /* GPBMessageTests+Merge.m in Sources */ = {isa = PBXBuildFile; fileRef = F4487C821AAF6AB300531423 /* GPBMessageTests+Merge.m */; };
 		F45C69CC16DFD08D0081955B /* GPBExtensionInternals.m in Sources */ = {isa = PBXBuildFile; fileRef = F45C69CB16DFD08D0081955B /* GPBExtensionInternals.m */; };
 		F45E57C71AE6DC6A000B7D99 /* text_format_map_unittest_data.txt in Resources */ = {isa = PBXBuildFile; fileRef = F45E57C61AE6DC6A000B7D99 /* text_format_map_unittest_data.txt */; };
+		F4B51B1E1BBC610700744318 /* GPBObjectiveCPlusPlusTest.mm in Sources */ = {isa = PBXBuildFile; fileRef = F4B51B1D1BBC610700744318 /* GPBObjectiveCPlusPlusTest.mm */; };
 		F4E675971B21D0000054530B /* Any.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = F4E675871B21D0000054530B /* Any.pbobjc.m */; };
 		F4E675991B21D0000054530B /* Api.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = F4E675891B21D0000054530B /* Api.pbobjc.m */; };
 		F4E6759B1B21D0000054530B /* Empty.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = F4E6758B1B21D0000054530B /* Empty.pbobjc.m */; };
@@ -193,6 +194,7 @@
 		F45C69CB16DFD08D0081955B /* GPBExtensionInternals.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBExtensionInternals.m; sourceTree = "<group>"; };
 		F45E57C61AE6DC6A000B7D99 /* text_format_map_unittest_data.txt */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = text_format_map_unittest_data.txt; sourceTree = "<group>"; };
 		F4AC9E1D1A8BEB3500BD6E83 /* unittest_cycle.proto */ = {isa = PBXFileReference; lastKnownFileType = text; path = unittest_cycle.proto; sourceTree = "<group>"; };
+		F4B51B1D1BBC610700744318 /* GPBObjectiveCPlusPlusTest.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = GPBObjectiveCPlusPlusTest.mm; sourceTree = "<group>"; };
 		F4B6B8AF1A9CC98000892426 /* GPBUnknownField_PackagePrivate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBUnknownField_PackagePrivate.h; sourceTree = "<group>"; };
 		F4B6B8B21A9CCBDA00892426 /* GPBUnknownFieldSet_PackagePrivate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBUnknownFieldSet_PackagePrivate.h; sourceTree = "<group>"; };
 		F4B6B8B61A9CD1DE00892426 /* GPBExtensionInternals.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBExtensionInternals.h; sourceTree = "<group>"; };
@@ -415,6 +417,7 @@
 				F4487C821AAF6AB300531423 /* GPBMessageTests+Merge.m */,
 				F4487C741AADF7F500531423 /* GPBMessageTests+Runtime.m */,
 				F4487C7E1AAF62CD00531423 /* GPBMessageTests+Serialization.m */,
+				F4B51B1D1BBC610700744318 /* GPBObjectiveCPlusPlusTest.mm */,
 				F41C175C1833D3310064ED4D /* GPBPerfTests.m */,
 				8BA9364418DA5F4B0056FA2A /* GPBStringTests.m */,
 				8B4248BA1A8C256A00BC1EC6 /* GPBSwiftTests.swift */,
@@ -668,6 +671,7 @@
 				8BBEA4AA147C727D00C4ADB7 /* GPBCodedOuputStreamTests.m in Sources */,
 				F4E675B21B21D0A70054530B /* SourceContext.pbobjc.m in Sources */,
 				8BBEA4AC147C727D00C4ADB7 /* GPBMessageTests.m in Sources */,
+				F4B51B1E1BBC610700744318 /* GPBObjectiveCPlusPlusTest.mm in Sources */,
 				F4487C7F1AAF62CD00531423 /* GPBMessageTests+Serialization.m in Sources */,
 				8B4248DC1A92933A00BC1EC6 /* GPBWellKnownTypesTest.m in Sources */,
 				F4E675B01B21D0A70054530B /* Empty.pbobjc.m in Sources */,
diff --git a/objectivec/ProtocolBuffers_iOS.xcodeproj/project.pbxproj b/objectivec/ProtocolBuffers_iOS.xcodeproj/project.pbxproj
index 23e9f169..14e51037 100644
--- a/objectivec/ProtocolBuffers_iOS.xcodeproj/project.pbxproj
+++ b/objectivec/ProtocolBuffers_iOS.xcodeproj/project.pbxproj
@@ -66,6 +66,7 @@
 		F4487C851AAF6AC500531423 /* GPBMessageTests+Merge.m in Sources */ = {isa = PBXBuildFile; fileRef = F4487C841AAF6AC500531423 /* GPBMessageTests+Merge.m */; };
 		F45C69CC16DFD08D0081955B /* GPBExtensionInternals.m in Sources */ = {isa = PBXBuildFile; fileRef = F45C69CB16DFD08D0081955B /* GPBExtensionInternals.m */; };
 		F45E57C91AE6DC98000B7D99 /* text_format_map_unittest_data.txt in Resources */ = {isa = PBXBuildFile; fileRef = F45E57C81AE6DC98000B7D99 /* text_format_map_unittest_data.txt */; };
+		F4B51B1C1BBC5C7100744318 /* GPBObjectiveCPlusPlusTest.mm in Sources */ = {isa = PBXBuildFile; fileRef = F4B51B1B1BBC5C7100744318 /* GPBObjectiveCPlusPlusTest.mm */; };
 		F4E675C81B21D1610054530B /* Any.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = F4E675B71B21D1440054530B /* Any.pbobjc.m */; };
 		F4E675C91B21D1610054530B /* Api.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = F4E675B91B21D1440054530B /* Api.pbobjc.m */; };
 		F4E675CA1B21D1610054530B /* Empty.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = F4E675BC1B21D1440054530B /* Empty.pbobjc.m */; };
@@ -214,6 +215,7 @@
 		F45C69CB16DFD08D0081955B /* GPBExtensionInternals.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBExtensionInternals.m; sourceTree = "<group>"; };
 		F45E57C81AE6DC98000B7D99 /* text_format_map_unittest_data.txt */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = text_format_map_unittest_data.txt; sourceTree = "<group>"; };
 		F4AC9E1C1A8BEB1000BD6E83 /* unittest_cycle.proto */ = {isa = PBXFileReference; lastKnownFileType = text; path = unittest_cycle.proto; sourceTree = "<group>"; };
+		F4B51B1B1BBC5C7100744318 /* GPBObjectiveCPlusPlusTest.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = GPBObjectiveCPlusPlusTest.mm; sourceTree = "<group>"; };
 		F4B6B8B01A9CC99500892426 /* GPBUnknownField_PackagePrivate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBUnknownField_PackagePrivate.h; sourceTree = "<group>"; };
 		F4B6B8B11A9CCBBB00892426 /* GPBUnknownFieldSet_PackagePrivate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBUnknownFieldSet_PackagePrivate.h; sourceTree = "<group>"; };
 		F4B6B8B31A9CD1C600892426 /* GPBExtensionInternals.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBExtensionInternals.h; sourceTree = "<group>"; };
@@ -453,6 +455,7 @@
 				F4487C841AAF6AC500531423 /* GPBMessageTests+Merge.m */,
 				F4487C761AADF84900531423 /* GPBMessageTests+Runtime.m */,
 				F4487C801AAF62FC00531423 /* GPBMessageTests+Serialization.m */,
+				F4B51B1B1BBC5C7100744318 /* GPBObjectiveCPlusPlusTest.mm */,
 				F41C175C1833D3310064ED4D /* GPBPerfTests.m */,
 				8BA9364418DA5F4B0056FA2A /* GPBStringTests.m */,
 				8B4248B31A8BD96E00BC1EC6 /* GPBSwiftTests.swift */,
@@ -770,6 +773,7 @@
 				F4E675CE1B21D1610054530B /* Type.pbobjc.m in Sources */,
 				F4353D1F1AB88243005A6198 /* GPBDescriptorTests.m in Sources */,
 				F4E675CF1B21D1610054530B /* Wrappers.pbobjc.m in Sources */,
+				F4B51B1C1BBC5C7100744318 /* GPBObjectiveCPlusPlusTest.mm in Sources */,
 				F4E675C81B21D1610054530B /* Any.pbobjc.m in Sources */,
 				8B4248B41A8BD96E00BC1EC6 /* GPBSwiftTests.swift in Sources */,
 				5102DABC1891A073002037B6 /* GPBConcurrencyTests.m in Sources */,
diff --git a/objectivec/Tests/GPBObjectiveCPlusPlusTest.mm b/objectivec/Tests/GPBObjectiveCPlusPlusTest.mm
new file mode 100644
index 00000000..9ba8fd0b
--- /dev/null
+++ b/objectivec/Tests/GPBObjectiveCPlusPlusTest.mm
@@ -0,0 +1,69 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2013 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+#import "GPBTestUtilities.h"
+
+
+//
+// This is just a compile test (here to make sure things never regress).
+//
+// Objective C++ can run into issues with how the NS_ENUM/CF_ENUM declartion
+// works because of the C++ spec being used for that compilation unit. So
+// the fact that these imports all work without errors/warning means things
+// are still good.
+//
+// The "well know types" should have cross file enums needing imports.
+#import "GPBProtocolBuffers.h"
+// Some of the tests explicitly use cross file enums also.
+#import "google/protobuf/Unittest.pbobjc.h"
+#import "google/protobuf/UnittestImport.pbobjc.h"
+
+// Sanity check the conditions of the test within the Xcode project.
+#if !__cplusplus
+  #error This isn't compiled as Objective C++?
+#elif __cplusplus >= 201103L
+  // If this trips, it means the Xcode default might have change (or someone
+  // edited the testing project) and it might be time to revisit the GPB_ENUM
+  // define in GPBBootstrap.h.
+  #warning Did the Xcode default for C++ spec change?
+#endif
+
+
+// Dummy XCTest.
+@interface GPBObjectiveCPlusPlusTests : GPBTestCase
+@end
+
+@implementation GPBObjectiveCPlusPlusTests
+- (void)testCPlusPlus {
+  // Nothing, This was a compile test.
+  XCTAssertTrue(YES);
+}
+@end