Shorthand names are intended to be used in the textual format of
references to instructions in another IR (which can't happen now, but
will be possible in a forthcoming PR). The shorthand name uses the file
name (minus the `.carbon` suffix) as a base, and if that base name is
ambiguous within the compilation, it is given a numerical suffix `.N`,
just like other textual IR names. Shorthand names are prefixed with `$`
in the textual format, to distinguish them from inst and scope names.
For example, a file `foo/bar.carbon` has the shorthand name `$bar`, and
an instruction `@baz.%qux` in that file can be referenced from another
file as `$bar.@baz.%qux`.
This PR adds `toolchain/check/testdata/basics/file_name.carbon` to test
this behavior. All other test changes are just applying this change to
the existing textual SemIR dumps.
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Co-authored-by: Dana Jansens <danakj@orodu.net>
Geoff RomerandDana Jansens
e67b6db910