tree a038c8dad6c52f509c19010a85915e02946daa03
parent a2e78a677a6b5220ec8175fbba3d0fc040a66ef2
author Giuliano Procida <gprocida@google.com> 1655739019 +0100
committer Giuliano Procida <gprocida@google.com> 1655754839 +0100

Make node types `struct` instead of `class`

This emphasises that the node types contain no hidden or mutable
state.

PiperOrigin-RevId: 456082057
Change-Id: Ia2ed03d99feac08f97759a8065b92d83d6806dca