api: api_info()['version']

API level is disconnected from NVIM version. The API metadata holds the
current API level, and the lowest backwards-compatible level supported
by this instance.

Release 0.1.6 is the first release that reports the Nvim version and API
level.

    metadata['version'] = {
      major: 0,
      minor: 1,
      patch: 6,
      api_level: 1,
      api_compatible: 0,
      api_prerelease: false,
    }

The API level may remain unchanged across Nvim releases if the API has
not changed.

When changing the API,
    - set NVIM_API_PRERELEASE to true
    - increment NVIM_API_LEVEL (at most once per Nvim version)
    - adjust NVIM_API_LEVEL_COMPAT if backwards-compatibility was broken

api_level_0.mpack was generated from Nvim 0.1.5 with:
    nvim --api-info

1 files changed, 2 insertions, 13 deletions

diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index 7fda2802c8..208c3b53c8 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -18,9 +18,9 @@
 #include "nvim/map.h"
 #include "nvim/option.h"
 #include "nvim/option_defs.h"
+#include "nvim/version.h"
 #include "nvim/eval/typval_encode.h"
 #include "nvim/lib/kvec.h"
-#include "auto/versiondef.h"
 
 /// Helper structure for vim_to_object
 typedef struct {
@@ -764,10 +764,10 @@ Dictionary api_metadata(void)
   static Dictionary metadata = ARRAY_DICT_INIT;
 
   if (!metadata.size) {
+    PUT(metadata, "version", DICTIONARY_OBJ(version_dict()));
     init_function_metadata(&metadata);
     init_error_type_metadata(&metadata);
     init_type_metadata(&metadata);
-    init_api_level_metadata(&metadata);
   }
 
   return copy_object(DICTIONARY_OBJ(metadata)).data.dictionary;
@@ -827,17 +827,6 @@ static void init_type_metadata(Dictionary *metadata)
 
   PUT(*metadata, "types", DICTIONARY_OBJ(types));
 }
-static void init_api_level_metadata(Dictionary *metadata)
-{
-  Dictionary version = ARRAY_DICT_INIT;
-  PUT(version, "current", INTEGER_OBJ(NVIM_API_CURRENT));
-  PUT(version, "compatibility", INTEGER_OBJ(NVIM_API_COMPATIBILITY));
-#ifdef NVIM_API_PRERELEASE
-  PUT(version, "prerelease", BOOLEAN_OBJ(true));
-#endif
-
-  PUT(*metadata, "api_level", DICTIONARY_OBJ(version));
-}
 
 /// Creates a deep clone of an object
 Object copy_object(Object obj)