Meta Issue: Fix developer instructions

[hermanventer]

Issue

If you like compilers and related tools, you are a meta-programmer, so you should like meta issues as well. This issue is a task to create tasks.

Since you are new here, please keep track of all of the surprises you've encountered and the things you had to find out the hard way. Then make an issue to get the fixed.

Ideally, follow that up with PR in which you fix it. Many thanks for doing that!

Steps to Reproduce

Read the developer documentation and try to fix an issue.

Expected Behavior

You got going with no problems and everything is crystal clear.

Actual Results

You muttered WTF on several occasions.

[johnperry-math]

I wouldn't mind helping with this, as I'm in that situation right now: cargo mirai never warns me about anything.

For example:

use argh::FromArgs;

#[derive(FromArgs)]
/// some args
struct Args {
    /// a value
    #[argh(positional)]
    a: usize,
}

pub fn main() {
    let args: Args = argh::from_env();
    let mut v: Vec<usize> = vec!();
    v.push(0);
    println!("{}", v[args.a]);
}

It ought to object strenuously to v[args.a], but I get nothing!

Following the instructions, I did:

git clone https://github.com/facebookexperimental/MIRAI.git
cd MIRAI
cargo install --locked --path ./checker
cd /path/to/crate
cargo mirai

So, what am I doing wrong? I wouldn't mind updating the instructions with an explanation of how to run it, including a sample program that is guaranteed to produce warnings on first run.

[hermanventer]

Ideally we need a new issue for each such problem. I.e. the is a meta issue and we need a concrete issue. :-)

[johnperry-math]

Whoops! I didn't realize that was the case. Thank you for opening an issue!