fix C generated code - support using in both C and C++ projects

Author: Ivan Dlugos

internal/generator/c/templates/binding-c.go

@@ -151,7 +151,12 @@ static bool {{$entity.Meta.CName}}_from_flatbuffer(const void* data, size_t size
 	const flatbuffers_uoffset_t* val;
 	size_t len;
 
-	*out_object = ({{$entity.Meta.CName}}) {0}; // reset so that dangling pointers are freed properly on malloc() failures
+	// reset so that dangling pointers are freed properly on malloc() failures
+#ifdef __cplusplus
+	*out_object = {};
+#else
+	*out_object = ({{$entity.Meta.CName}}){0};{{/* Only works in C99, fails to compile on MSVC in a C++ project*/}}
+#endif
 	{{range $property := $entity.Properties}}{{$propType := PropTypeName $property.Type -}}
 	if ((offset = {{$.FileIdentifier}}_fb_field_offset(vs, vt, {{$property.FbSlot}}))) {
 	{{- if $property.Meta.FbIsVector}}

test/comparison/testdata/fbs/typeful/c/schema.obx.h.expected

@@ -18,8 +18,7 @@ static obx_id schema_obx_h_put_object(OBX_box* box, void* object,
 static void* schema_obx_h_get_object(OBX_box* box, obx_id id, void* (*from_flatbuffer)(const void*, size_t));
 
 /// Internal function used in other generated functions to get a vTable offset for a given field.
-static flatbuffers_voffset_t schema_obx_h_fb_field_offset(flatbuffers_voffset_t vs, const flatbuffers_voffset_t* vt,
-                                                  size_t field);
+static flatbuffers_voffset_t schema_obx_h_fb_field_offset(flatbuffers_voffset_t vs, const flatbuffers_voffset_t* vt, size_t field);
 
 
 /// Entity documentation is copied
@@ -385,7 +384,12 @@ static bool Typeful_from_flatbuffer(const void* data, size_t size, Typeful* out_
     const flatbuffers_uoffset_t* val;
     size_t len;
 
-    *out_object = (Typeful) {0}; // reset so that dangling pointers are freed properly on malloc() failures
+    // reset so that dangling pointers are freed properly on malloc() failures
+#ifdef __cplusplus
+    *out_object = {};
+#else
+    *out_object = (Typeful){0};
+#endif
     if ((offset = schema_obx_h_fb_field_offset(vs, vt, 0))) {
         out_object->id = flatbuffers_uint64_read_from_pe(table + offset);
     }
@@ -672,7 +676,12 @@ static bool ns_Annotated_from_flatbuffer(const void* data, size_t size, ns_Annot
     const flatbuffers_uoffset_t* val;
     size_t len;
 
-    *out_object = (ns_Annotated) {0}; // reset so that dangling pointers are freed properly on malloc() failures
+    // reset so that dangling pointers are freed properly on malloc() failures
+#ifdef __cplusplus
+    *out_object = {};
+#else
+    *out_object = (ns_Annotated){0};
+#endif
     if ((offset = schema_obx_h_fb_field_offset(vs, vt, 0))) {
         out_object->identifier = flatbuffers_uint64_read_from_pe(table + offset);
     }
@@ -865,7 +874,12 @@ static bool ns_TSDate_from_flatbuffer(const void* data, size_t size, ns_TSDate*
     const flatbuffers_uoffset_t* val;
     size_t len;
 
-    *out_object = (ns_TSDate) {0}; // reset so that dangling pointers are freed properly on malloc() failures
+    // reset so that dangling pointers are freed properly on malloc() failures
+#ifdef __cplusplus
+    *out_object = {};
+#else
+    *out_object = (ns_TSDate){0};
+#endif
     if ((offset = schema_obx_h_fb_field_offset(vs, vt, 0))) {
         out_object->id = flatbuffers_uint64_read_from_pe(table + offset);
     }
@@ -967,7 +981,12 @@ static bool ns_TSDateNano_from_flatbuffer(const void* data, size_t size, ns_TSDa
     const flatbuffers_uoffset_t* val;
     size_t len;
 
-    *out_object = (ns_TSDateNano) {0}; // reset so that dangling pointers are freed properly on malloc() failures
+    // reset so that dangling pointers are freed properly on malloc() failures
+#ifdef __cplusplus
+    *out_object = {};
+#else
+    *out_object = (ns_TSDateNano){0};
+#endif
     if ((offset = schema_obx_h_fb_field_offset(vs, vt, 0))) {
         out_object->id = flatbuffers_uint64_read_from_pe(table + offset);
     }
@@ -1062,7 +1081,6 @@ static void* schema_obx_h_get_object(OBX_box* box, obx_id id, void* (*from_flatb
     return result;
 }
 
-static flatbuffers_voffset_t schema_obx_h_fb_field_offset(flatbuffers_voffset_t vs, 
-                                                  const flatbuffers_voffset_t* vt, size_t field) {
+static flatbuffers_voffset_t schema_obx_h_fb_field_offset(flatbuffers_voffset_t vs, const flatbuffers_voffset_t* vt, size_t field) {
     return (vs < sizeof(vt[0]) * (field + 3)) ? 0 : __flatbuffers_voffset_read_from_pe(vt + field + 2);
 }