Add error that arises from adding DefaultPlugin twice.

[mirkoRainer]

Objective

I was copy and pasting some code between projects and accidentally had .add_plugins(DefaultPlugins) twice. This resulted in thread 'main' panicked at 'Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins: SetGlobalDefaultError { _no_construct: () }', /Users/mirkorainer/.cargo/registry/src/github.com-1ecc6299db9ec823/bevy_log-0.5.0/src/lib.rs:85:22 note: run with 'RUST_BACKTRACE=1' environment variable to display a backtrace.

I understand this error to a degree, but I imagine importing Defaults could be a common mistake for beginners or people cobbling together examples found on blogs, etc. so wanted to add to the error message.

Solution

Added an extra sentence to the error message.

[alice-i-cecile]

Nice :) That should be a more helpful error message in a large fraction of the places that this shows up.

[mirkoRainer]

I agree with the wording change though. Being specific about adding it twice doesn’t catch the possibilities in a literal sense. Does the compiler prevent you from adding it three or more times? I know it does not for adding it twice. Compiler checks for this would be ideal but that’s outside my knowledge at this moment. Get Outlook for iOS<https://aka.ms/o0ukef>

________________________________ From: bjorn3 ***@***.***> Sent: Sunday, October 17, 2021 12:08:38 PM To: bevyengine/bevy ***@***.***> Cc: Mirko Rainer ***@***.***>; Author ***@***.***> Subject: Re: [bevyengine/bevy] Add error that arises from adding DefaultPlugin twice. (#2983) @bjorn3 commented on this pull request.

________________________________ In crates/bevy_log/src/lib.rs<#2983 (comment)>:

@@ -126,7 +126,7 @@ impl Plugin for LogPlugin {

let subscriber = subscriber.with(tracy_layer); bevy_utils::tracing::subscriber::set_global_default(subscriber) - .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins"); + .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins. Also, check that you're not accidentally adding DefaultPlugins twice."); It will immediately panic the second time you add it, so you don't even have the chance to add it a third time. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub<#2983 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AMTS6CHAQWUDZD4PMYMTII3UHLYINANCNFSM5GEEFCSQ>.

[mirkoRainer]

And by compiler, I mean a nice red squiggly line in the IDE. Get Outlook for iOS<https://aka.ms/o0ukef>

________________________________ From: Mirko Rainer ***@***.***> Sent: Sunday, October 17, 2021 12:42:21 PM To: bevyengine/bevy ***@***.***>; bevyengine/bevy ***@***.***> Cc: Author ***@***.***> Subject: Re: [bevyengine/bevy] Add error that arises from adding DefaultPlugin twice. (#2983) I agree with the wording change though. Being specific about adding it twice doesn’t catch the possibilities in a literal sense. Does the compiler prevent you from adding it three or more times? I know it does not for adding it twice. Compiler checks for this would be ideal but that’s outside my knowledge at this moment. Get Outlook for iOS<https://aka.ms/o0ukef>

________________________________ From: bjorn3 ***@***.***> Sent: Sunday, October 17, 2021 12:08:38 PM To: bevyengine/bevy ***@***.***> Cc: Mirko Rainer ***@***.***>; Author ***@***.***> Subject: Re: [bevyengine/bevy] Add error that arises from adding DefaultPlugin twice. (#2983) @bjorn3 commented on this pull request.

________________________________ In crates/bevy_log/src/lib.rs<#2983 (comment)>:

@@ -126,7 +126,7 @@ impl Plugin for LogPlugin {

let subscriber = subscriber.with(tracy_layer); bevy_utils::tracing::subscriber::set_global_default(subscriber) - .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins"); + .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins. Also, check that you're not accidentally adding DefaultPlugins twice."); It will immediately panic the second time you add it, so you don't even have the chance to add it a third time. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub<#2983 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AMTS6CHAQWUDZD4PMYMTII3UHLYINANCNFSM5GEEFCSQ>.

[bjorn3]

Does the compiler prevent you from adding it three or more times? I know it does not for adding it twice.

No, it doesn't.

[mockersf]

as part of a change on plugin initialization in #2988, I added a way to block adding the same plugin or the same plugin group twice

[alice-i-cecile]

This is ready for final review, but only one of #2983 or #2988 should be merged.

[alice-i-cecile]

Closing in favor of the more general #2988.