It's too easy to copy diagnostics around and lose track of Source::File
ownership. Ideally we'd place the shared_ptr on the Source, but Sources
are copied _very_ frequently, and we'd lose a huge amount of
performance. Typically, Source::Files are owned externally. The only
time we really need to hold a shared_ptr to these is when a Source::File
is generated by an ICE, as the File points to the C++ source file that
raised the error.
Bug: chromium:1292829
Bug: tint:1383
Change-Id: I2706de8775bc3366115865b5a94785c0b2fefaae
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78782
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
e1159c7180