Formatting of match arms with long guards is a bit awkward.

[emilio]

             match *token {
                 Token::Dimension {
                     value, ref unit, ..
-                } if num_context.is_ok(context.parsing_mode, value) =>
+                }
+                    if num_context.is_ok(context.parsing_mode, value) =>
                 {
                     return NoCalcLength::parse_dimension(context, value, unit)
                         .map(LengthOrPercentage::Length)
                         .map_err(|()| location.new_unexpected_token_error(token.clone()))
                 },

Not sure it's expected, feel free to close if so, but I have never seen a human use that formatting :)

[emilio]

Also, this looks like a regression, since the same code was rustfmt'd already a while ago.

[scampi]

@emilio This indentation is expected I think as per the style guide. @nrc should the guide be revised or close the issue as a wont fix ?

[nrc]

I think we didn't consider the case where there is a } on it's own line in the pattern of the match arm. In that case, I think we should apply the 'combining' rules. This could be clarified in the style guide.

[crumblingstatue]

I believe I'm experiencing the same issue with rust-sfml.
Diff from old to new rustfmt behavior:

diff --git a/examples/pong.rs b/examples/pong.rs
index 4bfa5ed..cf3928c 100644
--- a/examples/pong.rs
+++ b/examples/pong.rs
@@ -101,7 +103,8 @@ fn main() {
                 } => return,
                 Event::KeyPressed {
                     code: Key::Space, ..
-                } if !is_playing =>
+                }
+                    if !is_playing =>
                 {
                     // (re)start the game
                     is_playing = true;