internal: simplify ExtensionInfo initialization
This CL:
* Make the meaning of impl/ExtensionInfo.goType consistent. Before,
it was sometimes a T and other times a []T depending on the current
state of initialization. Change it so that it is the constructor's
responsibility to pass in a []T if it is repeated.
* Make internal/filetype responsible for constructing a []T for
repeated extension fields.
* Makes filedesc/Extension.Cardinality one of the eagerly initialized
pieces of information since it is useful to internal/filetype.
* Unify ExtensionInfo.desc and ExtensionInfo.tdesc.ExtensionField,
which held the same information.
* Remove the internal implementation for impl.X.ExtensionDescFromType
since we are dropping support for this from v1.
Change-Id: Ie95c4de66cd674c1d886da4f63b133b7d763c7ef
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/195777
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/impl/api_export.go b/internal/impl/api_export.go
index 3cb2ada..95e7846 100644
--- a/internal/impl/api_export.go
+++ b/internal/impl/api_export.go
@@ -140,5 +140,9 @@
// ExtensionDescFromType returns the legacy protoV1.ExtensionDesc for t.
func (Export) ExtensionDescFromType(t pref.ExtensionType) *ExtensionInfo {
- return legacyExtensionDescFromType(t)
+ // TODO: Delete this function when v1 directly does this assertion.
+ if xt, ok := t.(*ExtensionInfo); ok {
+ return xt
+ }
+ return nil
}