Rollup merge of #139100 - petrochenkov:errbelow, r=jieyouxu

compiletest: Support matching diagnostics on lines below

Using `//~vvv ERROR`.

This is not needed often, but it's easy to support, and it allows to eliminate a class of `error-pattern`s that cannot be eliminated in any other way.

See the diff for the examples of such patterns coming from parser.
Some of them can be matched by `//~ ERROR` or `//~^ ERROR` as well (when the final newline is allowed), but it changes the shape of reported spans, so I chose to keep the spans by using `//~v ERROR`.

0 files changed, 0 insertions, 0 deletions