If the condition of control flow expressions ends with closing parens and alike,
put the opening bracket of the body on the same line with closing parens.
rustfmt splits chain into multiline when the length of chain exceeds
`chain_one_line_max`. However, currenly this rule only applies when the chain
has more than one child. This can lead to unexpected long chain if the parent
is long. This commit adds heuristic that if the length of parent is longer
than the half of `chain_one_line_max` we use multiline even if there is
only a single child.
Preparation for #865, which proposes adding a flag which outputs which
config options are used during formatting.
This PR should not make any difference to functionality. A lot of this
was search-and-replace.
Some areas worthy of review/discussion:
- The method for each config item returns a clone of the underlying
value. We can't simply return an immutable reference, as lots of
places in the code expect to be able to pass the returned value as
`bool` (not `&bool). It would be nice if the `bool` items could
return a copy, but the more complex types a borrowed reference... but
unfortunately, I couldn't get the macro to do this.
- A few places (mostly tests and `src/bin/rustfmt.rs`) were overriding
config items by modifying the fields of the `Config` struct directly.
They now use the existing `override_value()` method, which has been
modified to return a `Result` for use by `src/bin/rustfmt.rs`. This
benefits of this are that the complex `file_lines` and `write_mode`
strings are now parsed in one place (`Config.override_value`) instead
of multiple. The disadvantages are that it moves the compile-time
checks for config names to become run-time checks.
