Function compiletest_rs::errors::load_errors

pub fn load_errors(testfile: &Path, cfg: Option<&str>) -> Vec<Error>

Looks for either "//~| KIND MESSAGE" or "//~^^... KIND MESSAGE" The former is a "follow" that inherits its target from the preceding line; the latter is an "adjusts" that goes that many lines up.

Goal is to enable tests both like: //~^^^ ERROR go up three and also //~^ ERROR message one for the preceding line, and //~| ERROR message two for that same line.

If cfg is not None (i.e., in an incremental test), then we look for //[X]~ instead, where X is the current cfg.