make Methods be exclusively virtual methods

These are the only kinds of methods that are tied to a class (via a
vtable). The others have independent existences as symbols.

Model changes:

`Method` node

* `kind` is removed
* `vtable_offset` is now non-optional

Format changes:

`method` node

* `kind` is removed along with all reader / writer support
* `vtable_offset` is now non-optional, so an absent field implies a 0
  offset
* "stable" IDs will differ

Note that the format version has not been bumped as there are no known
C++ STG ABIs in the wild.

PiperOrigin-RevId: 563736222
Change-Id: I37bb5a4e67f3d417492f0273ff5e6b4dff506bb4

1 files changed, 2 insertions, 10 deletions

diff --git a/stg.proto b/stg.proto
index e05684d..0937299 100644
--- a/stg.proto
+++ b/stg.proto
@@ -143,19 +143,11 @@ message BaseClass {
 }
 
 message Method {
-  enum Kind {
-    KIND_UNSPECIFIED = 0;
-    NON_VIRTUAL = 1;
-    STATIC = 2;
-    VIRTUAL = 3;
-  }
-
   fixed32 id = 1;
   string mangled_name = 2;
   string name = 3;
-  Kind kind = 4;
-  optional uint64 vtable_offset = 5;
-  fixed32 type_id = 6;
+  uint64 vtable_offset = 4;
+  fixed32 type_id = 5;
 }
 
 message Member {