thread 'main' panicked at lib.rs:376:47 because of empty code block in doc comment

[oovm]

Describe the bug

$ RUST_BACKTRACE=full cargo fmt
thread 'main' panicked at 'begin <= end (12 <= 11) when slicing `fn main() {}`', src\\lib.rs:376:47
stack backtrace:
   0:     0x7ff700d0665e - <unknown>
   1:     0x7ff700d1e72b - <unknown>
   2:     0x7ff700d02d98 - <unknown>
   3:     0x7ff700d092bd - <unknown>
   4:     0x7ff700d08d89 - <unknown>
   5:     0x7ff700d09b70 - <unknown>
   6:     0x7ff700d096a1 - <unknown>
   7:     0x7ff700d06fef - <unknown>
   8:     0x7ff700d095f9 - <unknown>
   9:     0x7ff700d1bcc0 - <unknown>
  10:     0x7ff700d218d6 - <unknown>
  11:     0x7ff70086b81d - <unknown>
  12:     0x7ff700844519 - <unknown>
  13:     0x7ff700846a9f - <unknown>
  14:     0x7ff70083f7a2 - <unknown>
  15:     0x7ff70094f5f0 - <unknown>
  16:     0x7ff70085dd83 - <unknown>
  17:     0x7ff700935e77 - <unknown>
  18:     0x7ff70092bc06 - <unknown>
  19:     0x7ff7009231a4 - <unknown>
  20:     0x7ff700936705 - <unknown>
  21:     0x7ff7009374f8 - <unknown>
  22:     0x7ff70080607d - <unknown>
  23:     0x7ff700838ea7 - <unknown>
  24:     0x7ff70080b9ca - <unknown>
  25:     0x7ff700815b07 - <unknown>
  26:     0x7ff70080b246 - <unknown>
  27:     0x7ff700812071 - <unknown>
  28:     0x7ff70080f162 - <unknown>
  29:     0x7ff70080d2b6 - <unknown>
  30:     0x7ff70080d5cc - <unknown>
  31:     0x7ff700d09e47 - <unknown>
  32:     0x7ff700816aa7 - <unknown>
  33:     0x7ff700d27714 - <unknown>
  34:     0x7fff6fcc7034 - BaseThreadInitThunk
  35:     0x7fff70782651 - RtlUserThreadStart

It's very strange.

There is no fn main() {} in my project, nor 376 lines in lib.rs

To Reproduce

The project can be found here: sdl-rs/sdl-ast@fe2daf4

Expected behavior

Meta

• rustfmt version: v1.4.36
• From where did you install rustfmt?: rustfmt_windows-x86_64-msvc_v1.4.36
• How do you run rustfmt:

Run RUST_BACKTRACE=full cargo fmt in MINGW64

[calebcartwright]

Important to note that rustup is the recommended and preferred way of getting the right components onto your system, but if you're going to download the pre-built binaries then I'd think for mingw you'd want to use rustfmt_windows-x86_64-gnu_v1.4.36.zip and not the msvc one, no?

[calebcartwright]

Thanks. The panic and line info is a reference to rustfmt, not your source input, and is related to some extra processing required in cases like formatting code blocks in comments.

Could you please try to distill your input down into a smaller reproducible example? Even getting down to a single file would be a helpful starting point as opposed to an entire project. You may want to try running with --verbose to get a better idea of which file contains the problematic area.

[oovm]

Everything is fine after removing: sdl-ast/src/ast/loops/mod.rs

So I think

/// ```
/// 
/// ```

gives this panic

[calebcartwright]

That's super helpful, thanks so much for reducing that to a minimal example!

[jplatte]

I get pretty much the same panic with some (broken) macro_rules! code, not sure whether it's the same root cause: Playground

[ytmimi]

going to close this in favor of #5234, as the issue is clearer in that issue