Roc on Windows Jul 2023 · beginners

I have used this machine previously to build Roc from source, so I may have already installed some dependencies like LLVM. However I had no issues today. I updated Visual Studio Build Tools 2019 with C++ to the latest version and then built roc using;

Cargo test

Running cargo test --release --locked builds and runs with 4 passed; 123 failed; 2 ignored.

Basic-cli

To build basic-cli I had to install a specific version of the rust nightly toolchain with

The examples build, however, I immediately hit a strange bug. For some reason Stdout.line does not print. However, when I add a dbg! statement in the platform it works (and also prints the dbg). I suspect there is something that is causing rust to not generate the code or it is being optimised away somehow. I'll do some further investigation.

Luke Boswell (Jul 23 2023 at 09:34):

Cool, I have no idea what I am doing, but I managed to open the .exe and attach a debugger which looks like this Screenshot-2023-07-23-193238.png.

Luke Boswell (Jul 23 2023 at 09:48):

Luke Boswell (Jul 23 2023 at 10:04):

Args example

Looks like the roc parser might be getting confused (there are not multi-line strings in the .roc example file).

roc build --optimize .\examples\args.roc
── INSUFFICIENT INDENT IN MULTI-LINE STRING ──────── .\examples\../src\Arg.roc ─

This multiline string is not sufficiently indented:

582│              """
583│
      ^

Lines in a multi-line string must be indented at least as much as the
beginning """. This extra indentation is automatically removed from
the string during compilation.

Command example

Not working. Builds ok (with --optimize) but then hangs when run. Debugging gives 0xC0000005: Access violation

Countdown example

roc build --optimize .\examples\countdown.roc
🔨 Rebuilding platform...
warning: ignoring debug info with an invalid version (0) in app
0 errors and 0 warnings found in 799 ms while successfully building:

    .\examples\countdown.exe
PS C:\Users\bosyl\Documents\GitHub\basic-cli> .\examples\countdown.exe

Let's count down from 3 together - all you have to do is press <ENTER>.


thread 'main' has overflowed its stack

Qqwy / Marten (Jul 23 2023 at 10:18):

Maybe stdout on Windows performs some buffering of output that is different than on Unix?
Does Stderr.line have the same problem or not?

Luke Boswell (Jul 23 2023 at 10:19):

Qqwy / Marten (Jul 23 2023 at 10:21):

The path .\examples\../src\Arg.roc looks very suspicious. Like Unix-style paths with forward slashes and Windows-style paths with backwards slashes get intermingled. Maybe that is what is confusing the parser?

Luke Boswell (Jul 23 2023 at 10:24):

Ok, so confirmed Stderr.line has the same issue. I'm 90% confident there is an issue in the Roc compiler here causing this.

For the Args example, I think it might be a roc parser issue. When git checkouts file on Windows it defaults to clrf \r\n line endings, but the parser assumes it is \n. We could maybe fix this with a gitattribute but I'm not sure what else that would affect, e.g. rust tooling etc.

Luke Boswell (Jul 23 2023 at 10:25):

Luke Boswell (Jul 23 2023 at 10:36):

PS C:\Users\bosyl\Documents\GitHub\roc-things> roc repl

  The rockin’ roc repl
────────────────────────

Enter an expression, or :help, or :q to quit.

»        1+1
warning: ignoring debug info with an invalid version (0) in
thread 'main' panicked at 'extern function roc_mmap is not defined by the builtins', crates\compiler\gen_llvm\src\llvm\externs.rs:176:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Stream: beginners

Topic: Roc on Windows Jul 2023

Luke Boswell (Jul 23 2023 at 09:23):

Building from source