cmd/protoc-gen-go: correlate v1 ExtensionDesc with v2 ExtensionType
Unfortunately a good amount of code uses pointer comparisons on the
v1 ExtensionDesc to determine exactly which extension field is set,
rather than checking whether the extension descriptor semantically
describes the field that they are interested in.
To preserve this behavior in v1, we need a 1:1 mapping between
a v2 ExtensionType and a specific v1 ExtensionDesc.
Change-Id: I852b3cefb4585bd656e48e5adad6cc28795d02df
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/167759
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/impl/legacy_extension.go b/internal/impl/legacy_extension.go
index ff464dc..83d5e99 100644
--- a/internal/impl/legacy_extension.go
+++ b/internal/impl/legacy_extension.go
@@ -163,7 +163,7 @@
if x.Desc != nil {
panic("extension descriptor already registered")
}
- x.Desc = legacyWrapper.ExtensionDescFromType(t)
+ x.Desc = extensionDescFromType(t)
if t.Cardinality() == pref.Repeated {
// If the field is repeated, initialize the entry with an empty list
// so that future Get operations can return a mutable and concrete list.
@@ -225,6 +225,15 @@
})
}
+func extensionDescFromType(typ pref.ExtensionType) *papi.ExtensionDesc {
+ if xt, ok := typ.(interface{ ProtoLegacyExtensionDesc() *papi.ExtensionDesc }); ok {
+ if desc := xt.ProtoLegacyExtensionDesc(); desc != nil {
+ return desc
+ }
+ }
+ return legacyWrapper.ExtensionDescFromType(typ)
+}
+
func extensionTypeFromDesc(desc *papi.ExtensionDesc) pref.ExtensionType {
if desc.Type != nil {
return desc.Type