AST nodes must not be shared. Diamonds in the AST will cause all sorts
of exciting, non trivial bugs.
All AST nodes must be reached by the Resolver. There are two common
reasons why they may not be:
(a) They were constructed and not attached to the AST. Several
transforms scan the full list of constructed AST nodes to find nodes
of a given type. Having detached nodes will likely cause bugs in
these transforms. Detached nodes is also just a waste of memory.
(b) They are attached to the AST, but the resolver did not traverse
them. Having the resolver skip over parts of the AST will fail to
catch validation issues, and will leave semantic gaps, likely
breaking downstream logic.
Bug: tint:469
Change-Id: I143b84fd830699f874d2936146f0e93197db610c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/47778
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
6fcefe4c25