unstable fingerprints error with mockall 0.10 #112430
Comments
matt-phylum
added
C-bug
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First, unstable proc macros should very much not cause incremental problems, proc macros run before incremental kicks in. It does make it way harder to debug though. Do you have a simple way to reproduce it? |
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Maybe it shouldn't, but if I use Interestingly, expanding the I managed to remove a few more things. This version doesn't use Crashing code: use paste::paste;
// This constant allows us to rebuild without changing anything in this file.
#[allow(unused)]
const RANDOM: &str = include_str!("rand.txt");
type Callback<T> = Box<dyn FnOnce(&mut T) + 'static>;
// This struct doesn't seem like it should do anything, but removing it stops the crash.
struct MockDaoA;
#[mockall::automock]
trait DaoB {
fn method<'life0, 'life1>(&'life0 self, param: &'life1 usize);
}
// Removing this send constraint stops the crash.
struct Wrapper<M>(Callback<M>)
where
M: Send;
// Expanding this macro by hand stops the crash?
macro_rules! builder_struct {
($($dao_impl:ty),* $(,)?) => {
paste! {
struct Builder{
$(
[< $dao_impl:snake >]: Wrapper<$dao_impl>,
)*
}
#[allow(unused)]
impl Builder {
$(
fn [< with_mock_ $dao_impl:snake>] (
mut self,
config_callback: Callback<$dao_impl>,
) {
self.[< $dao_impl:snake >] = Wrapper(config_callback);
}
)*
}
}
}
}
builder_struct!(MockDaoA, MockDaoB);Non crashing code: // This constant allows us to rebuild without changing anything in this file.
#[allow(unused)]
const RANDOM: &str = include_str!("rand.txt");
type Callback<T> = Box<dyn FnOnce(&mut T) + 'static>;
// This struct doesn't seem like it should do anything, but removing it stops the crash.
struct MockDaoA;
#[mockall::automock]
trait DaoB {
fn method<'life0, 'life1>(&'life0 self, param: &'life1 usize);
}
// Removing this send constraint stops the crash.
struct Wrapper<M>(Callback<M>)
where
M: Send;
struct Builder {
mock_dao_a: Wrapper<MockDaoA>,
mock_dao_b: Wrapper<MockDaoB>,
}
#[allow(unused)]
impl Builder {
fn with_mock_mock_dao_a(mut self, config_callback: Callback<MockDaoA>) {
self.mock_dao_a = Wrapper(config_callback);
}
fn with_mock_mock_dao_b(mut self, config_callback: Callback<MockDaoB>) {
self.mock_dao_b = Wrapper(config_callback);
}
}That paste macro isn't very complicated and has stable output. |
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It's definitely related to asomers/mockall#333. I pulled down the mockall code and bisected. asomers/mockall@e2f5285 is the first commit where it doesn't crash. |
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the nondeterminism probably exhibits a specific pattern that makes rustc crash. I don't think this is worth your time debugging if it doesn't ICE on beta anymore. It's unlikely that you'll reveal new things about it. it was probably fixed by #11195. |
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awesome, thanks! closing it as completed then |
I think this problem is related to asomers/mockall#333. Upgrading to Mockall 0.11.4 is one of the things that prevents it from happening.
I'm not seeing the crash on beta 1.71.0-beta.2, but I can't see a bug for this so I don't know if that's intentional. When I upgraded to 1.70 it seemed like almost every other build I would get a crash. Coworkers downgraded to 1.69 because of it, so to me it seems like a good candidate for backporting if it's not already planned.
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rustc --version --verbose:Error output
Backtrace
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