wasm-validator errors when trying to compile rust-brotli to wasm32

[lilianmoraru]

rustc stable: rustc 1.17.0 (56124ba 2017-04-24)
rustc nightly: rustc 1.19.0-nightly (76242ae 2017-06-06)
emcc:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 1.37.13
clang version 4.0.0 (https://github.com/kripken/emscripten-fastcomp-clang/ a1ed3cfe03ddc6c3a581adc412276e7841df8e5f) (https://github.com/kripken/emscripten-fastcomp/ cd8feb18426289a8ed7a7ac9e5dac2ea663d09bf) (emscripten 1.37.13 : 1.37.13)

---

I tried to compile Dropbox's rust-brotli to Wasm32 and the results look like this, on both Rust stable and nightly:

• [Pass] --target=asmjs-unknown-emscripten
• [Pass] --target=asmjs-unknown-emscripten --features "no-stdlib"
• [Fail] --target=wasm32-unknown-emscripten
• [Fail] --target=wasm32-unknown-emscripten --features "no-stdlib"

Note that the base library that it uses for decompression, compiled alright in all combinations.
I also tested on a "Hello World" binary and all compiles ok.

---

Here are the logs(sorry, these are to big for gist and also Git doesn't want to accept the archive in this issue) for cargo +nightly build --target=wasm32-unknown-emscripten --verbose:

• 45.1 MB txt file: https://drive.google.com/open?id=0B36L1TDvAttnTXU3VkpzTGEzdWc
• 1.4 MB XZ compressed(same file): https://drive.google.com/open?id=0B36L1TDvAttnd0c4SGRsek5NUFU

[malbarbo]

Some libc definitions are wrong for emscripten target, see rust-lang/libc#610.

Here is a small example that fails to compile:

use std::fs::File;
use std::io::{Seek, SeekFrom};

fn main() {
    let mut f = File::open("x.txt").unwrap();
    f.set_len(5).unwrap();
    f.seek(SeekFrom::Start(2)).unwrap();
}

It works for asmjs (I think because there is no validation), but fails for wasm32. The error is:

[wasm-validator error in function $__ZN3std2fs4File7set_len17h668c1fb11d26e7feE] 2 != 1: call param types must match, on
[i32] (call $_ftruncate
 [i32] (get_local $3)
 [i64] (get_local $2)
)
[wasm-validator error in function $__ZN47__LT_std__fs__File_u20_as_u20_std__io__Seek_GT_4seek17h53361e7da9834951E] 2 != 1: call param types must match, on
[i32] (call $_lseek
 [i32] (get_local $5
 [i64] (get_local $22)
 [i32] (get_local $24)
)

The problem is that off_t should be i32 but was i64. Although the libc patch are tested against asmjs, I think that it will work for wasm32.

After the libc PR get merged, it is necessary to update libc in rust. Well, I hope this assertions are correct, after all, the tests are green.

[lilianmoraru]

Still doesn't compile on nightly :(
Even with --features no-stdlib

[Enselic]

Triage: Is this still a problem 6 years later? (If it would be easy to check I would check myself, but doesn't seem easy to check.)

[Enselic]

Triage: Assuming not a problem any longer. Closing.