[PATCH v1 4/4] xdrgen: Take a union's numeric discriminant width from the declaration

[Chuck Lever <cel@kernel.org>]

_XdrUnion.max_width() counts the discriminant as one XDR word, while
symbolic_width() takes the discriminant's width from the discriminant
declaration. For a hyper discriminant, or a typedef of one, the _sz
macro therefore emits two words where the numeric width counts one.
program.py compares the numeric widths of each procedure's argument
type to choose the type that the *_MAX_ARGS_SZ macro expands to, so a
union argument with a wide discriminant can lose that comparison to a
narrower type. RFC 4506 restricts the discriminant to int, unsigned
int, bool, and enum, and every in-tree .x file complies, so the
generated headers do not change.

Take the numeric discriminant width from the discriminant declaration
as well, so the two methods agree by construction.

Signed-off-by: Chuck Lever <cel@kernel.org>
---
 tools/net/sunrpc/xdrgen/xdr_ast.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/net/sunrpc/xdrgen/xdr_ast.py b/tools/net/sunrpc/xdrgen/xdr_ast.py
index 6b012f0f7a42..a57b5f42da1f 100644
--- a/tools/net/sunrpc/xdrgen/xdr_ast.py
+++ b/tools/net/sunrpc/xdrgen/xdr_ast.py
@@ -514,7 +514,7 @@ class _XdrUnion(_XdrAst):
         if self.default:
             if self.default.arm.max_width() > max_width:
                 max_width = self.default.arm.max_width()
-        return 1 + max_width
+        return self.discriminant.max_width() + max_width
 
     def symbolic_width(self) -> List:
         """Return list containing XDR width of type's components"""
-- 
2.56.0