Another similar example:

Before

    PA[08].configure(Some(A)); // FTDI_RTS - USART0 RTS
    PA[09].configure(None);    // ACC_INT1 - FXOS8700CQ Interrupt 1
    PA[10].configure(None);    // unused
    PA[11].configure(Some(A)); // FTDI_OUT - USART0 RX FTDI->SAM4L
    PA[12].configure(Some(A)); // FTDI_IN - USART0 TX SAM4L->FTDI
    PA[13].configure(None);    // RED_LED
    PA[14].configure(None);    // BLUE_LED
    PA[15].configure(None);    // GREEN_LED

After

    PA[08].configure(Some(A)); // FTDI_RTS - USART0 RTS
    PA[09].configure(None); // ACC_INT1 - FXOS8700CQ Interrupt 1
    PA[10].configure(None); // unused
    PA[11].configure(Some(A)); // FTDI_OUT - USART0 RX FTDI->SAM4L
    PA[12].configure(Some(A)); // FTDI_IN - USART0 TX SAM4L->FTDI
    PA[13].configure(None); // RED_LED
    PA[14].configure(None); // BLUE_LED
    PA[15].configure(None); // GREEN_LED

I think the general rule here is that vertically aligned // comment should not have leading whitespace removed.

rustfmt v0.6.3 used to leave these alone, v0.7.1 now corrupts them

Rustfmt is not smart enough to maintain alignment like this, I think what happened is that it always tried to remove the whitespace, but for some reason did not manage to do so in some cases, and that set of cases has changed.

Rustfmt is not smart enough to maintain alignment like this, I think what happened is that it always tried to remove the whitespace, but for some reason did not manage to do so in some cases, and that set of cases has changed.

When there are comments in between binary expressions or chain, rustfmt gives up and just copy & paste the original snippet. That's why the comments inside binary operations are kept aligned, while the spaces between ; and the last line comment is properly removed into a single space.

In my case I actually want the opposite behaviour, e.g. to stop this:

    let res = pipe!(
        2, // 2
        |x| x * 10, // 20
        |x| x - 3, // 17
        |x| x   5, // 22
    );

from becoming this:

    let res = pipe!(
        2,          // 2
        |x| x * 10, // 20
        |x| x - 3,  // 17
        |x| x   5,  // 22
    );

In my case I actually want the opposite behaviour, e.g. to stop this:

    let res = pipe!(
        2, // 2
        |x| x * 10, // 20
        |x| x - 3, // 17
        |x| x   5, // 22
    );

from becoming this:

    let res = pipe!(
        2,          // 2
        |x| x * 10, // 20
        |x| x - 3,  // 17
        |x| x   5,  // 22
    );

@teohhanhui - Realize it's a similar theme, but what you're talking about is actually unrelated and a duplicate of #4108