Don't use underscores in argument names for derive output #49676

Manishearth · 2018-04-05T01:20:26Z

Currently in the docs #[derive()]d functions show up with arguments like __arg0, __arg1, etc.

Ideally they'd have descriptive names set by the derive, but for now I'd just like to remove the underscores.

The underscores exist so that the unused_variable lint isn't triggered, but there's a simpler solution there -- don't run that pass for these functions.

In a followup I'll make it possible for consumers of the builtin derive helpers to specify argument names; or teach rust/rustdoc to scrape them off the trait.

r? @jseyfried @eddyb

cc @QuietMisdreavus

TimNN · 2018-04-05T01:42:45Z

Your PR failed on Travis. Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:00:47] configure: rust.quiet-tests     := True
---
[00:20:20] error: unused variable: `arg_0`
[00:20:20]    --> libcore/fmt/mod.rs:104:43
[00:20:20]     |
[00:20:20] 104 | #[derive(Copy, Clone, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
[00:20:20]     |                                           ^^^^ help: consider using `_arg_0` instead
---
[00:20:20]   process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc --crate-name core libcore/lib.rs --color always --error-format json --crate-type lib --emit=dep-info,link -C opt-level=2 -C metadata=64878136ec7adadb -C extra-filename=-64878136ec7adadb --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps --target x86_64-unknown-linux-gnu -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/release/deps` (exit code: 101)
[00:20:20] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "--release" "--locked" "--color" "always" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "--message-format" "json"
[00:20:20] expected success, got: exit code: 101
[00:20:20] thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1075:9
[00:20:20] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[00:20:20] travis_fold:end:stage1-std
[00:20:20] travis_time:end:stage1-std:start=1522892524791158261,finish=1522892560294824940,duration=35503666679
[00:20:20] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap build
[00:20:20] Build completed unsuccessfully in 0:15:40
[00:20:20] make: *** [all] Error 1
[00:20:20] Makefile:28: recipe for target 'all' failed

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN.

Manishearth · 2018-04-05T01:46:51Z

Also fixed this hygiene issue

TimNN · 2018-04-05T02:07:50Z

Your PR failed on Travis. Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:00:45] configure: rust.quiet-tests     := True
---
[00:20:29] error: unused variable: `arg_0`
[00:20:29]   --> libcore/ops/range.rs:48:38
[00:20:29]    |
[00:20:29] 48 | #[derive(Copy, Clone, PartialEq, Eq, Hash)]
[00:20:29]    |                                      ^^^^ help: consider using `_arg_0` instead
---
[00:20:29]    = note: #[deny(unused_variables)] implied by #[deny(warnings)]
[00:20:29]
[00:20:29] error: unused variable: `arg_0`
[00:20:29]     --> libcore/option.rs:1219:62
[00:20:29]      |
[00:20:29] 1219 | #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
[00:20:29]      |                                                              ^^^^ help: consider using `_arg_0` insteaderror: aborting due to 3 previous errors
[00:20:29]
[00:20:29] error: Could not compile `core`.
[00:20:29]
[00:20:29] Caused by:
[00:20:29]   process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc --crate-name core libcore/lib.rs --color always --error-format json --crate-type lib --emit=dep-info,link -C opt-level=2 -C metadata=64878136ec7adadb -C extra-filename=-64878136ec7adadb --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps --target x86_64-unknown-linux-gnu -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/release/deps` (exit code: 101)
[00:20:29] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "--release" "--locked" "--color" "always" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "--message-format" "json"
[00:20:29] expected success, got: exit code: 101
[00:20:29] thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1075:9
---
$ ls -lat $HOME/Library/Logs/DiagnosticReports/
ls: cannot access /home/travis/Library/Logs/DiagnosticReports/: No such file or directory
travis_time:end:0080f462:start=1522894067532624521,finish=1522894067540015082,duration=7390561
travis_fold:end:after_failure.2
travis_fold:start:after_failure.3
travis_time:start:172d5d91
$ find $HOME/Library/Logs/DiagnosticReports -type f -name '*.crash' -not -name '*.stage2-*.crash' -not -name 'com.apple.CoreSimulator.CoreSimulatorService-*.crash' -exec printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" {} \; -exec head -750 {} \; -exec echo travis_fold":"end:crashlog \; || true
find: `/home/travis/Library/Logs/DiagnosticReports': No such file or directory

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN.

TimNN · 2018-04-05T02:23:14Z

Your PR failed on Travis. Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:00:48] configure: rust.quiet-tests     := True
---
[00:07:08] error[E0412]: cannot find type `Item` in this scope
[00:07:08]    --> librustc/middle/liveness.rs:188:39
[00:07:08]     |
[00:07:08] 188 |     fn visit_item(&mut self, i: &'tcx Item) {
[00:07:08]     |                                       ^^^^ not found in this scope
[00:07:08] help: possible candidates are found in other modules, you can import them into scope
---
[00:07:42] Makefile:28: recipe for target 'all' failed
[00:07:42] make: *** [all] Error 1

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN.

TimNN · 2018-04-05T02:46:12Z

Your PR failed on Travis. Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:00:45] configure: rust.quiet-tests     := True
---
[00:26:46] error: unused variable: `arg_0`
[00:26:46]   --> libcore/ops/range.rs:48:38
[00:26:46]    |
[00:26:46] 48 | #[derive(Copy, Clone, PartialEq, Eq, Hash)]
[00:26:46]    |                                      ^^^^ help: consider using `_arg_0` instead
---
[00:26:46]    = note: #[deny(unused_variables)] implied by #[deny(warnings)]
[00:26:46]
[00:26:46] error: unused variable: `arg_0`
[00:26:46]     --> libcore/option.rs:1219:62
[00:26:46]      |
[00:26:46] 1219 | #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
[00:26:46]      |                                                              ^^^^ help: consider using `_arg_0` instead
[00:26:46]
[00:26:46] error: unused variable: `arg_0`
[00:26:46]    --> libcore/fmt/mod.rs:104:43
[00:26:46]     |
[00:26:46] 104 | #[derive(Copy, Clone, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
[00:26:46]     |                                           ^^^^ help: consider using `_arg_0` instead
---
[00:26:46]   process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc --crate-name core libcore/lib.rs --color always --error-format json --crate-type lib --emit=dep-info,link -C opt-level=2 -C metadata=64878136ec7adadb -C extra-filename=-64878136ec7adadb --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps --target x86_64-unknown-linux-gnu -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/release/deps` (exit code: 101)
[00:26:46] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "--release" "--locked" "--color" "always" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "--message-format" "json"
[00:26:46] expected success, got: exit code: 101
[00:26:46] thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1075:9
[00:26:46] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[00:26:46] travis_fold:end:stage1-std
[00:26:46] travis_time:end:stage1-std:start=1522896251938877462,finish=1522896304702149128,duration=52763271666
[00:26:46] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap build
[00:26:46] Build completed unsuccessfully in 0:21:03
[00:26:46] make: *** [all] Error 1
[00:26:46] Makefile:28: recipe for target 'all' failed
---
$ ls -lat $HOME/Library/Logs/DiagnosticReports/
ls: cannot access /home/travis/Library/Logs/DiagnosticReports/: No such file or directory
travis_time:end:0b4036c2:start=1522896305293935512,finish=1522896305302693988,duration=8758476
travis_fold:end:after_failure.2
travis_fold:start:after_failure.3
travis_time:start:0ad5f5a6
$ find $HOME/Library/Logs/DiagnosticReports -type f -name '*.crash' -not -name '*.stage2-*.crash' -not -name 'com.apple.CoreSimulator.CoreSimulatorService-*.crash' -exec printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" {} \; -exec head -750 {} \; -exec echo travis_fold":"end:crashlog \; || true
find: `/home/travis/Library/Logs/DiagnosticReports': No such file or directory
travis_time:end:0ad5f5a6:start=1522896305310069248,finish=1522896305317522163,duration=7452915
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:09350d47
$ dmesg | grep -i kill
[   10.683938] init: failsafe main process (1093) killed by TERM signal

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN.

Manishearth · 2018-04-05T02:51:15Z

Argh I need a clean way to do this.

I guess I can just check the span but that's kinda cheating :/

Manishearth · 2018-04-05T03:56:09Z

Oh, that's an older failure.

@TimNN looks like the bot shows failures from travis builds on stale commits?

(Also, would be nice to have a way to ask the bot to not post for WIP PRs, either by detecting WIP in the title or a @timnnbot shh command)

Manishearth · 2018-04-05T04:01:17Z

Stuff passes now, but the partialord stuff isn't fixed:

error[E0530]: match bindings cannot shadow constants
 --> test.rs:9:7
  |
4 | pub const cmp: u8 = 1;
  | ---------------------- a constant `cmp` is defined here
...
9 |     B(u8)
  |       ^^^ cannot be named the same as a constant

because cmp @ _ is not enough to avoid shadowing.

Which makes me realize that the __self_0 stuff is broken too, because:

pub const __self_0: u8 = 1;

#[derive(PartialOrd, PartialEq)]
pub enum Foo {
    A(u8), B(u8)
}

will hit it on the ref bindings.

Yay.

TimNN · 2018-04-05T04:03:14Z

@Manishearth: Thanks for the feedback! Both features are already planned and should be implemented by the end of the week(end).

Manishearth · 2018-04-05T04:03:42Z

That error exists because of #33118, specifically because

pub const A = ...
let A = ...

match ... {
  A => ...
}

will resolve A in the match as a binding, however this will not occur if the let doesn't exist. Disallowing shadowing constants entirely is the duct tape to keep this from being weird. Hmm.

Manishearth · 2018-04-05T04:03:52Z

@TimNN thanks!

Manishearth · 2018-04-05T04:05:56Z

At least for __cmp we still have a fix: We can do it as a two step pass where we do let foo = cmp(..); match cmp { Equal => ..., _ => cmp}. However the __self stuff is used inside proper pattern matches which we need to make work somehow. So the cmp stuff can't be fixed.

Manishearth · 2018-04-05T04:10:54Z

(Since I removed the commit now, my above rambling is about a potential fix I had for #49679 )

Manishearth · 2018-04-05T04:28:01Z

Ugh, we still have other issues:

pub const arg_0: u8 = 1;
fn foo(arg_0: bool) {}

itself will type error because arg_0 the pattern resolves to the constant, not a binding. So keeping the underscores may be for the best since it's harder to have a shadowing constant that way.

The ability to use constants as patterns should really be removed for patterns in an irrefutable context. It is already disallowed, but not at the right stage.

Manishearth · 2018-04-05T04:32:07Z

Blocked on #49680

eddyb · 2018-04-05T06:25:22Z

Note the difference between unhygienic old macros and hygienic new macros.

durka · 2018-04-05T16:58:17Z

src/librustc/middle/liveness.rs

+    if let FnKind::Method(..) = fk {
+        let parent = ir.tcx.hir.get_parent(id);
+        if let Some(hir::map::Node::NodeItem(i)) = ir.tcx.hir.find(parent) {
+            if i.attrs.iter().any(|a| a.check_name("automatically_derived")) {


Does this cover custom derive?

pietroalbini · 2018-04-09T10:10:38Z

As per #49676 (comment), this is blocked on #49680.

eddyb · 2018-04-10T12:45:47Z

@pietroalbini Not necessarily, see #49676 (comment).

pietroalbini · 2018-04-10T12:48:45Z

Oh, sorry, I misunderstood that comment :)

pietroalbini · 2018-04-16T10:51:41Z

Ping from triage! What's the status of this PR?

Manishearth · 2018-04-16T16:56:34Z

Probably superseded by #49986, if not, I'll reopen

Don't use underscores for argument names in #[derive()] expansions

6aecb1c

rust-highfive assigned jseyfried Apr 5, 2018

Manishearth force-pushed the derive-underscores branch 2 times, most recently from 0fcb9ff to 19e83c8 Compare April 5, 2018 02:16

Don't run unused variable pass for stuff generated by #[derive()]

d5a304e

Manishearth force-pushed the derive-underscores branch from 19e83c8 to bdb99e4 Compare April 5, 2018 02:28

Manishearth force-pushed the derive-underscores branch from bdb99e4 to d5a304e Compare April 5, 2018 04:06

pietroalbini added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 5, 2018

petrochenkov mentioned this pull request Apr 5, 2018

We shouldn't even try to resolve irrefutable patterns as constants #49680

Closed

durka reviewed Apr 5, 2018

View reviewed changes

pietroalbini added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 9, 2018

pietroalbini added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-blocked Status: Blocked on something else such as an RFC or other implementation work. labels Apr 10, 2018

pietroalbini added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Apr 16, 2018

Manishearth closed this Apr 16, 2018

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Don't use underscores in argument names for derive output #49676

Don't use underscores in argument names for derive output #49676

Manishearth commented Apr 5, 2018

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Manishearth commented Apr 16, 2018

Don't use underscores in argument names for derive output #49676

Don't use underscores in argument names for derive output #49676

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