ci: use --feature-powerset --depth 2 in features check

[taiki-e]

Motivation

As has been pointed out a few times in the past (e.g., #4036 (comment)), each-feature is not sufficient for features check.

Ideally, we'd like to check all combinations of features, but there are too many combinations.
So limit the max number of simultaneous feature flags to 2 by --depth option. I think this should be sufficient in most cases as @carllerche said in taiki-e/cargo-hack#58.

[Darksonn]

LGTM

[taiki-e]

hmm...

info: running `cargo check -Z avoid-dev-deps --no-default-features --features rt,signal` on tokio (56/225)
   Compiling tokio v1.21.1 (/home/runner/work/tokio/tokio/tokio)
error[E0308]: mismatched types
  --> tokio/src/runtime/driver.rs:46:58
   |
46 |                 IoStack::Enabled(v) => IoUnpark::Enabled(v.handle()),
   |                                        ----------------- ^^^^^^^^^^ expected struct `runtime::io::Handle`, found struct `signal::unix::driver::Handle`
   |                                        |
   |                                        arguments to this enum variant are incorrect
   |
note: tuple variant defined here
  --> tokio/src/runtime/driver.rs:20:9
   |
20 |         Enabled(crate::runtime::io::Handle),
   |         ^^^^^^^

For more information about this error, try `rustc --explain E0308`.
error: could not compile `tokio` due to previous error
error: process didn't exit successfully: `/home/runner/.rustup/toolchains/nightly-2022-07-26-x86_64-unknown-linux-gnu/bin/cargo check -Z avoid-dev-deps --manifest-path tokio/Cargo.toml --no-default-features --features rt,signal` (exit status: 101)

[taiki-e]

The problem seems to be that the type returned by the handle method of the SignalDriver (used as ProcessDriver when the process feature is disabled) is different from that of ProcessDriver.

tokio/tokio/src/runtime/driver.rs

Lines 125 to 143 in 0fddb76

	// ===== process driver =====
	cfg_process_driver! {
	type ProcessDriver = crate::process::unix::driver::Driver;
	fn create_process_driver(signal_driver: SignalDriver) -> ProcessDriver {
	crate::process::unix::driver::Driver::new(signal_driver)
	}
	}
	cfg_not_process_driver! {
	cfg_io_driver! {
	type ProcessDriver = SignalDriver;
	fn create_process_driver(signal_driver: SignalDriver) -> ProcessDriver {
	signal_driver
	}
	}
	}

However, crate::signal::unix::driver::Handle that returned by SignalDriver::handle doesn't have unpark method, so the following simple patch doesn't seem to work.

diff --git a/tokio/src/runtime/driver.rs b/tokio/src/runtime/driver.rs
index 2a0deb80..6ef98825 100644
--- a/tokio/src/runtime/driver.rs
+++ b/tokio/src/runtime/driver.rs
@@ -17,7 +17,7 @@ pub(crate) enum IoStack {
     }
 
     pub(crate) enum IoUnpark {
-        Enabled(crate::runtime::io::Handle),
+        Enabled(ProcessHandle),
         Disabled(UnparkThread),
     }
 
@@ -127,6 +127,7 @@ fn create_signal_driver(io_driver: IoDriver) -> io::Result<(SignalDriver, Signal
 
 cfg_process_driver! {
     type ProcessDriver = crate::process::unix::driver::Driver;
+    type ProcessHandle = crate::runtime::io::Handle;
 
     fn create_process_driver(signal_driver: SignalDriver) -> ProcessDriver {
         crate::process::unix::driver::Driver::new(signal_driver)
@@ -136,6 +137,7 @@ fn create_process_driver(signal_driver: SignalDriver) -> ProcessDriver {
 cfg_not_process_driver! {
     cfg_io_driver! {
         type ProcessDriver = SignalDriver;
+        type ProcessHandle = crate::signal::unix::driver::Handle;
 
         fn create_process_driver(signal_driver: SignalDriver) -> ProcessDriver {
             signal_driver

$ cargo check -Z avoid-dev-deps --manifest-path tokio/Cargo.toml --no-default-features --features rt,signal
error[E0599]: no method named `unpark` found for reference `&signal::unix::driver::Handle` in the current scope
  --> tokio/src/runtime/driver.rs:77:43
   |
77 |                 IoUnpark::Enabled(v) => v.unpark(),
   |                                           ^^^^^^ method not found in `&signal::unix::driver::Handle`

For more information about this error, try `rustc --explain E0599`.

[taiki-e]

cc @ipetkov

[carllerche]

Seems like we do need this!

[carllerche]

@taiki-e I can work on fixing this build error since it is from my work.

[carllerche]

This build error happened because I incorrectly combined "handle" and "unpark" when I got rid of the Park trait. I will keep them separate for now to fix the build.

[carllerche]

Thanks for this!