Trim imports for bundled generated protos.

To avoid a cycle between headers, have the WKTs use minimal imports instead
of using the helper to get everything from the library.

Fixes protocolbuffers#4301
Fixes protocolbuffers#4403

Author: thomasvl

objectivec/GPBProtocolBuffers_RuntimeSupport.h

@@ -31,7 +31,7 @@
 // This header is meant to only be used by the generated source, it should not
 // be included in code using protocol buffers.
 
-#import "GPBProtocolBuffers.h"
+#import "GPBBootstrap.h"
 
 #import "GPBDescriptor_PackagePrivate.h"
 #import "GPBExtensionInternals.h"

objectivec/google/protobuf/Any.pbobjc.h

@@ -214,7 +214,17 @@ FileGenerator::~FileGenerator() {
 }
 
 void FileGenerator::GenerateHeader(io::Printer *printer) {
-  PrintFileRuntimePreamble(printer, "GPBProtocolBuffers.h");
+  std::set<string> headers;
+  // Generated files bundled with the library get minimal imports, everything
+  // else gets the wrapper so everything is usable.
+  if (IsProtobufLibraryBundledProtoFile(file_)) {
+    headers.insert("GPBRootObject.h");
+    headers.insert("GPBMessage.h");
+    headers.insert("GPBDescriptor.h");
+  } else {
+    headers.insert("GPBProtocolBuffers.h");
+  }
+  PrintFileRuntimePreamble(printer, headers);
 
   // Add some verification that the generated code matches the source the
   // code is being compiled with.
@@ -337,7 +347,9 @@ void FileGenerator::GenerateHeader(io::Printer *printer) {
 
 void FileGenerator::GenerateSource(io::Printer *printer) {
   // #import the runtime support.
-  PrintFileRuntimePreamble(printer, "GPBProtocolBuffers_RuntimeSupport.h");
+  std::set<string> headers;
+  headers.insert("GPBProtocolBuffers_RuntimeSupport.h");
+  PrintFileRuntimePreamble(printer, headers);
 
   // Enums use atomic in the generated code, so add the system import as needed.
   if (FileContainsEnums(file_)) {
@@ -566,7 +578,7 @@ void FileGenerator::GenerateSource(io::Printer *printer) {
 // files. This currently only supports the runtime coming from a framework
 // as defined by the official CocoaPod.
 void FileGenerator::PrintFileRuntimePreamble(
-    io::Printer* printer, const string& header_to_import) const {
+    io::Printer* printer, const std::set<string>& headers_to_import) const {
   printer->Print(
       "// Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
       "// source: $filename$\n"
@@ -575,22 +587,39 @@ void FileGenerator::PrintFileRuntimePreamble(
 
   const string framework_name(ProtobufLibraryFrameworkName);
   const string cpp_symbol(ProtobufFrameworkImportSymbol(framework_name));
+
   printer->Print(
       "// This CPP symbol can be defined to use imports that match up to the framework\n"
       "// imports needed when using CocoaPods.\n"
       "#if !defined($cpp_symbol$)\n"
       " #define $cpp_symbol$ 0\n"
       "#endif\n"
       "\n"
-      "#if $cpp_symbol$\n"
-      " #import <$framework_name$/$header$>\n"
-      "#else\n"
-      " #import \"$header$\"\n"
+      "#if $cpp_symbol$\n",
+      "cpp_symbol", cpp_symbol);
+
+
+  for (std::set<string>::const_iterator iter = headers_to_import.begin();
+       iter != headers_to_import.end(); ++iter) {
+    printer->Print(
+        " #import <$framework_name$/$header$>\n",
+        "header", *iter,
+        "framework_name", framework_name);
+  }
+
+  printer->Print(
+      "#else\n");
+
+  for (std::set<string>::const_iterator iter = headers_to_import.begin();
+       iter != headers_to_import.end(); ++iter) {
+    printer->Print(
+        " #import \"$header$\"\n",
+        "header", *iter);
+  }
+
+  printer->Print(
       "#endif\n"
-      "\n",
-      "cpp_symbol", cpp_symbol,
-      "header", header_to_import,
-      "framework_name", framework_name);
+      "\n");
 }
 
 }  // namespace objectivec

objectivec/google/protobuf/Api.pbobjc.h

@@ -74,7 +74,7 @@ class FileGenerator {
   const Options options_;
 
   void PrintFileRuntimePreamble(
-      io::Printer* printer, const string& header_to_import) const;
+      io::Printer* printer, const std::set<string>& headers_to_import) const;
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FileGenerator);
 };