[SYCL] Move variadic call diagnostics to delayed diagnostics, fixes.#998

Merged

bader merged 3 commits intointel:syclfrom

erichkeane:variadic_funcs_change

Jan 15, 2020

Commits on Jan 10, 2020

[SYCL] Move variadic call diagnostics to delayed diagnostics, fixes.
Erich Keane
committed

Commits on Jan 13, 2020

[SYCL] Revert inadvertant change in test from previous commit
Erich Keane
committed

Commits on Jan 14, 2020

[SYCL] Remove FIXME comment that this invalidates.
Erich Keane
committed