Simplify coverage tests

[richkadel]

This change reduces the risk of impacting coverage tests on unrelated
changes (such as MIR and Span changes), and reduces the burden when
blessing coverage changes in case it is necessary.

• Remove all spanview tests. The spanview tests were useful during
  development, but they can be generated as needed, via compiler command
  line flags. They aren't critical to confirming coverage results. (The
  coverage report tests are sufficient.)

  When spanview regeneration was necessary, the diffs were way too hard
  to read to be useful anyway. So I'm removing them to reduce friction
  from a feature that is no longer useful.

• Remove the requirement for llvm-cov show --debug when blessing
  tests. The --debug flag is, unfortunately, only available if LLVM is
  built with optimize = false (in Rust's config.toml). This adds
  significant time and resource burdens to the contributor's build. As
  it turns out, for other reasons in the past, I wasn't actually using
  the debug output (counter info) to validate coverage anymore either,
  so it was required for no reason, I now realize.

[rust-highfive]

r? @Mark-Simulacrum

(rust-highfive has picked a reviewer for you, use r? to override)

[richkadel]

r? tmandry

[richkadel]

This addresses the problems discussed in #83663 (comment)

[jyn514]

r? @tmandry

[richkadel]

oops! Thanks Josh.

[tmandry]

@bors r+

[bors]

📌 Commit 9c0eda76a1edb871f652f34fd0bb898ed2c02e12 has been approved by tmandry

[bors]

☔ The latest upstream changes (presumably #83663) made this pull request unmergeable. Please resolve the merge conflicts.

[petrochenkov]

Why are the tests run-make-fulldeps rather than run-make though?

Fulldeps tests are very special and should only be used for legacy plugins and other uses of the compiler as a library, any regular compiler use doesn't need it. Unnecessary use of fulldeps is a huge waste of time due to the compiler being built twice.

[richkadel]

Why are the tests run-make-fulldeps rather than run-make though?

I'm surprised no one has ever said anything about this in the past year, but thanks for suggesting it. I'll try moving them and if there are no side effects, I'll include the move in this cleanup PR.

Thanks!

[richkadel]

if there are no side effects, I'll include the move in this cleanup PR.

For some reason, the llvm-cov tool is failing. I'm going to look into this some other time, but will leave it out of this PR for now.

[richkadel]

@tmandry (or anyone) I've resolved the conflicts. Can someone please resubmit this to bors for me?

Thanks!

[jyn514]

@bors r=tmandry

[bors]

📌 Commit fad5388 has been approved by tmandry

[jyn514]

For some reason, the llvm-cov tool is failing. I'm going to look into this some other time, but will leave it out of this PR for now.

@richkadel Did you remember to build the demangler for run-make, not just run-make-fulldeps?

rust/src/bootstrap/test.rs

Lines 1180 to 1182 in e87c4dd

	if mode == "run-make" && suite.ends_with("fulldeps") {
	let rust_demangler = builder
	.ensure(tool::RustDemangler { compiler, target, extra_features: Vec::new() })

Not sure if llvm-cov is related to the demangler, but that stood out as needing changes.

[richkadel]

Did you remember to build the demangler for run-make, not just run-make-fulldeps?

Thanks @jyn514 !

Right, I also noticed that when I was updating bootstrap a couple of weeks ago. I'm sure that is a problem. I'm not sure if it's the only reason it failed, but possibly. (The error I saw didn't seem related to rust-demangler, but who knows how that might have manifested.)

I did create a new github Issue for this, and mentioned the bootstrap change there: #83830