Specifying checks as a string is convenient for quickly using
clang-tidy to run a handful of checks. However it is not
suitable for projects that have a long list of enabled or
disabled checks. It is specially troublesome in case one
wants to interleave comments with the checks, to explain
why they are enabled or disabled.
Currently this can be achieved via multiline strings in YAML,
but it's error-prone. For example, comments must end with a
comma for clang-tidy to continue processing the list of globs;
a missing comma will make clang-tidy silently ignore the rest
of the list.
Instead, enable passing a native YAML list to the "Checks"
option in the config file. The implementation is done such
that the old behavior is kept: a user can pass a string
or a list. We can consider deprecating passing the checks
as a string altogether in a future release, to simplify
the internal logic of the YAML parser.
Any reason for this line changing, this formatting change looks unrelated.