[c++ grpc] Fix includes when bond::Void is used

When a service contains events or parameterless methods, the generated
code uses bond::Void as the request/result type. To serialize
bond::Void, bond_reflection.h needs to be included.

The generated service code now includes bond_reflection.h if any service
contains an event or a parameterless method.

Fixes microsoft#735

CHANGELOG.md

@@ -46,6 +46,8 @@ different versioning scheme, following the Haskell community's
   has required Boost 1.58 or later since version 5.2.0, but this was not
   enforced.
 * gRPC v1.7.1 is now required to use Bond-over-gRPC.
+* Fixed includes for gRPC services with events or parameterless methods.
+  [Issue #735](https://github.com/Microsoft/bond/issues/735)
 
 ## 7.0.2: 2017-10-30 ##
 * `gbc` & compiler library: 0.10.1.0

compiler/src/Language/Bond/Codegen/Cpp/Grpc_h.hs

@@ -6,6 +6,7 @@
 module Language.Bond.Codegen.Cpp.Grpc_h (grpc_h) where
 
 import System.FilePath
+import Data.Maybe(isNothing)
 import Data.Monoid
 import Prelude
 import qualified Data.Text.Lazy as L
@@ -27,6 +28,7 @@ grpc_h export_attribute cpp file imports declarations = ("_grpc.h", [lt|
 #include "#{file}_reflection.h"
 #include "#{file}_types.h"
 #{newlineSep 0 includeImport imports}
+#{includeBondReflection}
 #include <bond/core/bonded.h>
 #include <bond/ext/grpc/bond_utils.h>
 #include <bond/ext/grpc/client_callback.h>
@@ -79,6 +81,14 @@ grpc_h export_attribute cpp file imports declarations = ("_grpc.h", [lt|
             paramsText = toLazyText params
             padLeft = if L.head paramsText == ':' then [lt| |] else mempty
 
+    includeBondReflection =
+      if usesBondVoid then [lt|#include <bond/core/bond_reflection.h>|] else mempty
+      where usesBondVoid = any declUses declarations
+            declUses Service {serviceMethods = methods } = any methodUses methods
+            declUses _ = False
+            methodUses Function {methodInput = input } = isNothing input
+            methodUses Event {} = True
+
     grpc s@Service{..} = [lt|
 #{template}class #{declName} final
 {

compiler/tests/generated/generic_service_grpc.h

@@ -4,6 +4,7 @@
 #include "generic_service_reflection.h"
 #include "generic_service_types.h"
 
+#include <bond/core/bond_reflection.h>
 #include <bond/core/bonded.h>
 #include <bond/ext/grpc/bond_utils.h>
 #include <bond/ext/grpc/client_callback.h>

compiler/tests/generated/service_attributes_grpc.h

@@ -4,6 +4,7 @@
 #include "service_attributes_reflection.h"
 #include "service_attributes_types.h"
 
+
 #include <bond/core/bonded.h>
 #include <bond/ext/grpc/bond_utils.h>
 #include <bond/ext/grpc/client_callback.h>

compiler/tests/generated/service_grpc.h

@@ -5,6 +5,7 @@
 #include "service_types.h"
 #include "basic_types_grpc.h"
 #include "namespace_basic_types_grpc.h"
+#include <bond/core/bond_reflection.h>
 #include <bond/core/bonded.h>
 #include <bond/ext/grpc/bond_utils.h>
 #include <bond/ext/grpc/client_callback.h>