fn next()

in src/compiler/diab.rs [405:455]

• 26 lines of code
• 9 McCabe index (conditional complexity)

    fn next(&mut self) -> Option<OsString> {
        loop {
            let arg = self.stack.pop()?;

            // Just return non @ arguments
            if !arg.starts_with("-@") {
                return Some(arg);
            }

            let value = match arg.split_prefix("-@") {
                Some(arg) => arg,
                None => return Some(arg),
            };

            // Return options that produce additional output and are not cacheable
            if value.starts_with("E") || value.starts_with("O") || value.starts_with("@") {
                return Some(arg);
            }

            // According to diab [1], @file means:
            // Read command line options from either a file or an environment
            // variable. When -@name is encountered on the command line, the
            // driver first looks for an environment variable with the given
            // name and substitutes its value. If an environment variable is
            // not found then the driver tries to open a file with given name
            // and substitutes the contents of the file. If neither an
            // environment variable or a file can be found, an error message
            // is issued and the driver terminates.
            //
            // [1]: http://www.vxdev.com/docs/vx55man/diab5.0ppc/c-invoke.htm#3000619
            //
            // The environment variable feature is *not* supported by sccache
            // since this would raise the need for the clients environment
            // and not just env::var. This is technically possible, but
            // considered as a unneeded edge case for now.

            let mut contents = String::new();
            let file = self.cwd.join(&value);
            let res = File::open(file).and_then(|mut f| f.read_to_string(&mut contents));
            if res.is_err() {
                // Failed to read the file, so return the argument as it is.
                // This will result in a CannotCache.
                return Some(arg);
            }
            if contents.contains('"') || contents.contains('\'') {
                return Some(arg);
            }
            let new_args = contents.split_whitespace().collect::<Vec<_>>();
            self.stack.extend(new_args.iter().rev().map(|s| s.into()));
        }
    }