rustfmt shifts macro body 4 indent levels to the right for no reason

[Boscop]

Version:

$ cargo fmt --version
rustfmt 1.6.0-nightly (1065d87 2023-07-09)

Config:

edition = "2021"
version = "Two"
max_width = 110
newline_style = "Unix"
use_small_heuristics = "Max"
tab_spaces = 2
imports_granularity = "Crate"
use_field_init_shorthand = true
use_try_shorthand = true
spaces_around_ranges = true
overflow_delimited_expr = true

I have this code:

      macro dst_port($name:ident, $node:expr, $lock_dst_node:expr, $port_id:expr, $dst_node_id:expr) {
        macro $name() {
          // TODO: Assign to val instead of re-reading on every access, since it's not overwritten before all reads are done
          $node.ports[$port_id]
        }
      }

after running rustfmt, it shifted the inner macro body 4 indent levels (4*2 spaces) to the right for no reason!:

      macro dst_port($name:ident, $node:expr, $lock_dst_node:expr, $port_id:expr, $dst_node_id:expr) {
        macro $name() {
                  // TODO: Assign to val instead of re-reading on every access, since it's not overwritten before all reads are done
                  $node.ports[$port_id]
                }
      }

Note: This doesn't happen when the comment is shorter like:

      macro dst_port($name:ident, $node:expr, $lock_dst_node:expr, $port_id:expr, $dst_node_id:expr) {
        macro $name() {
          // TODO: Assign to val instead of re-reading on every access
          $node.ports[$port_id]
        }
      }

It also doesn't happen when the original long comment is before the inner macro like:

      macro dst_port($name:ident, $node:expr, $lock_dst_node:expr, $port_id:expr, $dst_node_id:expr) {
        // TODO: Assign to val instead of re-reading on every access, since it's not overwritten before all reads are done
        macro $name() {
          $node.ports[$port_id]
        }
      }

[ytmimi]

@Boscop thanks for reaching out. The long line comment is definitely the issue here, and as you've highlighted this is only an issue when the comment is inside the inner macro definition.

You have a few options for how to deal with this. You can

1. increase the max_width
2. set wrap_comments=true to allow rustfmt to wrap the long line comment
3. manually wrap the long line comment so that it's under the max_width

This is likely related to #4609 and other macro indentation issues.