Diagnostics hold a pointer to the source, used for printing the source in the error message.
Because of this, the source must live at least as long as the diag::list.
Fixed: chromium:1232097
Change-Id: Iad8b30a2bd69f505dd8bb0eadc5a35115400d047
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/59360
Auto-Submit: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: James Price <jrprice@google.com>