Remove dead code in rustc_session::Options

[jyn514]

• Don't recompile the same functions for each debugging option
  This reduces the amount of items in the crate by quite a lot.
• Remove unused parse_opt_list and parse_pathbuf_push functions
• Remove unused macro parameters
• Remove allow(dead_code).

[rust-highfive]

r? @petrochenkov

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

[jyn514]

I expect this should help bootstrap time for rustc_session quite a bit (other crates shouldn't be affected).

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit 2828dec942bdc6c8299dbc74411bfa1270ebbf79 with merge 5ce9808b3b5bfb44d46efe3fe2d5d152fd51f39a...

[jyn514]

Err ... I guess there's not a way to cancel an ongoing try run, and I don't know a way to tell rust-timer to queue a commit that isn't the latest.

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit b19c02c with merge a64224eaa14138ddc834a78d854d070df9154409...

[Mark-Simulacrum]

Overall looks fine to me, presuming perf is happy.

[Mark-Simulacrum]

nit: one of these uses $crate, the other does not. Doesn't matter in practice as it's crate local (I think) but let's be consistent.

[jyn514]

Sure thing - I made this change locally, but I don't want to push since it will cancel the perf run.

diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 735188768e4..cd28517bfbc 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -286,7 +286,7 @@ fn dep_tracking_hash(&self, _for_crate_hash: bool, error_format: ErrorOutputType
 
     pub type $setter_name = fn(&mut $struct_name, v: Option<&str>) -> bool;
     pub const $stat: &[(&str, $setter_name, &str, &str)] =
-        &[ $( (stringify!($opt), crate::options::parse::$opt, $crate::options::desc::$parse, $desc) ),* ];
+        &[ $( (stringify!($opt), $crate::options::parse::$opt, $crate::options::desc::$parse, $desc) ),* ];
 
     // Sometimes different options need to build a common structure.
     // That structure can kept in one of the options' fields, the others become dummy.

[bors]

☀️ Try build successful - checks-actions
Build commit: a64224eaa14138ddc834a78d854d070df9154409 (a64224eaa14138ddc834a78d854d070df9154409)

[rust-timer]

Queued a64224eaa14138ddc834a78d854d070df9154409 with parent 6e2a344, future comparison URL.

[rust-timer]

Finished benchmarking try commit (a64224eaa14138ddc834a78d854d070df9154409): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf

[jyn514]

It looks like the time for rustc_session went ... up? 😕 the compiler should be doing strictly less work, maybe it's just noise?

[Mark-Simulacrum]

Likely noise. Dead code doesn't usually influence performance too much as it's not generally codegen'd, and rustc itself is pretty fast. This still seems like an improvement overall to me, though, at least in terms of readability. @bors r+

[bors]

📌 Commit b19c02c has been approved by Mark-Simulacrum

[bors]

⌛ Testing commit b19c02c with merge 89ebad5...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing 89ebad5 to master...