Strange symbols don't roundtrip through wasm2wat and wat2wasm

[jtgeibel]

Over in alexcrichton/wasm-gc#8 I'm experimenting with demangling rust symbols in wasm output. This results in symbol names such as <alloc::vec::Vec<T>>::extend_from_slice and <&'a T as core::fmt::Debug>::fmt.

While wasm2wat produces very nice looking output, I get a segmentation fault when feeding this output back into wat2wasm. I'm guessing that the space characters are causing issues when parsing the .wat file but other characters could be causing problems as well.

example.wasm.gz

[binji]

Ah, I see! Yeah, this seems to be a limitation of the text format, since any utf-8 sequence is allowed for a name in the binary format. For now, I guess wasm2wat should probably just produce a replacement character.

I wasn't able to repro the segfault though, here's what I tried:

$ wasm2wat wasm.gc.wasm -o wasm.gc.wat
$ wat2wasm wasm.gc.wat
wasm.gc.wat:82:15: error: unexpected token T, expected ).
  (func $<&'a T as core::fmt::Display>::fmt::h0bee0bd948d5b839 (type 2) (para...
              ^
wasm.gc.wat:82:17: error: unexpected token as.
  (func $<&'a T as core::fmt::Display>::fmt::h0bee0bd948d5b839 (type 2) (para...
                ^^
wasm.gc.wat:82:20: error: unexpected token core::fmt::Display>::fmt::h0bee0bd948d5b839.
  (func $<&'a T as core::fmt::Display>::fmt::h0bee0bd948d5b839 (type 2) (para...
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
wasm.gc.wat:82:70: error: unexpected token 2, expected (.
...::fmt::Display>::fmt::h0bee0bd948d5b839 (type 2) (param i32 i32) (result i32)
                                                 ^

[keithw]

Closing as this no longer segfaults or produces an error, although the question of roundtrippability, and the issue to be fixed by #1661, still seem outstanding.