Inline `if .. else` expression

[barosl]

if .. else is sometimes used in lieu of the ternary operator in C, so it might be a good idea to preserve the original intention if the programmer wrote a short if .. else expression in a single line.

A wild case found in rust-lang/rust#28988:

if align <= MIN_ALIGN { 0 } else { mallocx_align(align) }

was converted into:

if align <= MIN_ALIGN {
    0
} else {
    mallocx_align(align)
}

which looks a bit more verbose. Is this an intended behavior?

Hmm, well, looking at the code again, the latter also seems OK to me... Now I'm not sure which side I'm in. Maybe this should be exposed as a configuration option?

[nrc]

It is intended, but it's a style that's often requested, so we should probably have an option for it.

(I thought there was an issue for this already, but I couldn't find one).

[mseri]

+1 on this. There are some libraries in rust-lang in which this change is made all-over the place, even for very short lines (e.g. libfmt_macros, although in many cases I prefer rustfmt style).

[marcusklaas]

This is already possible by setting single_line_if_else to true in the config!

[marcusklaas]

https://github.com/nrc/rustfmt/blob/master/tests/target/single-line-if-else.rs has some example output.

[nrc]

Ha! That is why I couldn't find an issue :-)

[mseri]

Ah cool! Thanks!!

[wfxr]

@marcusklaas Was option single_line_if_else removed?

$ rustfmt --version
rustfmt 1.4.11-nightly (1838235 2019-12-03)
$ rustfmt main.rs
Warning: Unknown configuration option `single_line_if_else`

[marcusklaas]

I do not know. I haven't been involved with this project for a long time.

[enigmartyr]

even with single_line_if_else if the if-else statement is your return value then the formatter will still open the statement up unless you explicitly use the return keyword (which I believe isn't idiomatic, ironically)