Update the ObjC version checks to support a min and current version.

- Capture the version used to generated.
- Check at compile time and runtime that generated code isn't from a newer
  version, also check that the min version required is also supported.
- Keep the old constants/macros/functions to special case the last version
  that was working so those generated sources still work until we decide
  otherwise.

1 files changed, 14 insertions, 10 deletions

diff --git a/src/google/protobuf/compiler/objectivec/objectivec_file.cc b/src/google/protobuf/compiler/objectivec/objectivec_file.cc
index 878a3743..7ad127bb 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_file.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_file.cc
@@ -51,10 +51,8 @@ namespace objectivec {
 
 namespace {
 
-// This is also found in GPBBootstrap.h, and needs to be kept in sync.  It
-// is the version check done to ensure generated code works with the current
-// runtime being used.
-const int32 GOOGLE_PROTOBUF_OBJC_GEN_VERSION = 30002;
+// This is also found in GPBBootstrap.h, and needs to be kept in sync.
+const int32 GOOGLE_PROTOBUF_OBJC_VERSION = 30002;
 
 const char* kHeaderExtension = ".pbobjc.h";
 
@@ -192,13 +190,19 @@ void FileGenerator::GenerateHeader(io::Printer *printer) {
 
   // Add some verification that the generated code matches the source the
   // code is being compiled with.
+  // NOTE: This captures the raw numeric values at the time the generator was
+  // compiled, since that will be the versions for the ObjC runtime at that
+  // time.  The constants in the generated code will then get their values at
+  // at compile time (so checking against the headers being used to compile).
   printer->Print(
-      "#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != $protoc_gen_objc_version$\n"
-      "#error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.\n"
+      "#if GOOGLE_PROTOBUF_OBJC_VERSION < $google_protobuf_objc_version$\n"
+      "#error This file was generated by a newer version of protoc which is incompatible with your Protocol Buffer library sources.\n"
+      "#endif\n"
+      "#if $google_protobuf_objc_version$ < GOOGLE_PROTOBUF_OBJC_MIN_SUPPORTED_VERSION\n"
+      "#error This file was generated by an older version of protoc which is incompatible with your Protocol Buffer library sources.\n"
       "#endif\n"
       "\n",
-      "protoc_gen_objc_version",
-      SimpleItoa(GOOGLE_PROTOBUF_OBJC_GEN_VERSION));
+      "google_protobuf_objc_version", SimpleItoa(GOOGLE_PROTOBUF_OBJC_VERSION));
 
   // #import any headers for "public imports" in the proto file.
   {
@@ -392,7 +396,7 @@ void FileGenerator::GenerateSource(io::Printer *printer) {
         "  // about thread safety and initialization of registry.\n"
         "  static GPBExtensionRegistry* registry = nil;\n"
         "  if (!registry) {\n"
-        "    GPBDebugCheckRuntimeVersion();\n"
+        "    GPB_DEBUG_CHECK_RUNTIME_VERSIONS();\n"
         "    registry = [[GPBExtensionRegistry alloc] init];\n");
 
     printer->Indent();
@@ -487,7 +491,7 @@ void FileGenerator::GenerateSource(io::Printer *printer) {
         "  // about thread safety of the singleton.\n"
         "  static GPBFileDescriptor *descriptor = NULL;\n"
         "  if (!descriptor) {\n"
-        "    GPBDebugCheckRuntimeVersion();\n");
+        "    GPB_DEBUG_CHECK_RUNTIME_VERSIONS();\n");
     if (vars["objc_prefix"].size() > 0) {
       printer->Print(
           vars,