Use track_errors instead of hand-rolling such a check

[oli-obk]

Const eval asserts that reporting an error for statics actually worked. This is not only done in a wrong way (checks for no error having happened in the entire compilation), it's also very fragile. We should instead use the track_errors method around the report_as_error call, and in case track_errors returns Ok, we need to do the delay_span_bug.

The relevant code that needs to be changed can be found in

rust/src/librustc_mir/const_eval.rs

Lines 645 to 654 in 16e7e05

	let reported_err = err.report_as_error(ecx.tcx,
	"could not evaluate static initializer");
	// Ensure that if the above error was either `TooGeneric` or `Reported`
	// an error must be reported.
	if tcx.sess.err_count() == 0 {
	tcx.sess.delay_span_bug(err.span,
	&format!("static eval failure did not emit an error: {:#?}",
	reported_err));
	}
	reported_err

[estebank]

Wouldn't using track_errors cause the compiler to stop at const evaluation? Ideally we would want the compiler to choose a reasonable recovery value (just a binding of TyErr?) and continue to minimize the loop of "fix 5 errors, get 300 errors" (#39275).

[oli-obk]

track_errors doesn't actually stop anything. It just gives you a Result::Err if new errors occured and a Result::Ok otherwise.

[JohnTitor]

@oli-obk I want to solve this, could I open a PR(and ask you to review)?

[oli-obk]

Jup! It's all yours!