cmd/protoc-gen-go: unexport implementation-specific XXX fields
We modify protoc-gen-go to stop generating exported XXX fields.
The unsafe implementation is unaffected by this change since unsafe
can access fields regardless of visibility. However, for the purego
implementation, we need to respect Go visibility rules as enforced
by the reflect package.
We work around this by generating a exporter function that given
a reference to the message and the field to export, returns a reference
to the unexported field value. This exporter function is protected by
a constant such that it is not linked into the final binary in non-purego
build environment.
Updates golang/protobuf#276
Change-Id: Idf5c1f158973fa1c61187ff41440acb21c5dac94
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/185141
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/impl/pointer_unsafe.go b/internal/impl/pointer_unsafe.go
index 39f1995..bd5ab4b 100644
--- a/internal/impl/pointer_unsafe.go
+++ b/internal/impl/pointer_unsafe.go
@@ -11,12 +11,14 @@
"unsafe"
)
+const UnsafeEnabled = true
+
// offset represents the offset to a struct field, accessible from a pointer.
// The offset is the byte offset to the field from the start of the struct.
type offset uintptr
// offsetOf returns a field offset for the struct field.
-func offsetOf(f reflect.StructField) offset {
+func offsetOf(f reflect.StructField, x exporter) offset {
return offset(f.Offset)
}