Internal Compiler Error in 1.30 and 1.31

[daniel-fontaine]

This library compiled without issue in rust versions prior to 1.30.

error: internal compiler error: broken MIR in DefId(0/0:1339 ~ zeta[1bd0]::cp[0]::solver[0]::sequential[0]::{{impl}}[1]::with_search[0]) (const cp::solver::CPSolver::with_heuristic): bad constant user type Canonical { variables: [], value: fn(std::sync::Arc<modeling::Model>, cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>, F>) -> cp::solver::sequential::CPSequentialSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<<cp::solver::backtracking::copying::CopyingBacktracker as cp::solver::backtracking::Backtracker>::Node>>, F>> {<cp::solver::sequential::CPSequentialSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<<cp::solver::backtracking::copying::CopyingBacktracker as cp::solver::backtracking::Backtracker>::Node>>, F>> as cp::solver::CPSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>, F>>>::with_heuristic} } vs fn(std::sync::Arc<modeling::Model>, cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>, F>) -> cp::solver::sequential::CPSequentialSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>, F>> {<cp::solver::sequential::CPSequentialSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>, F>> as cp::solver::CPSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>, F>>>::with_heuristic}: NoSolution
  --> src/cp/solver/sequential.rs:70:9                                                                                                                                                        
   |                                                                                                                                                                                          
70 | /         <Self as CPSolver<CustomSearchFactory<CPWorker<B, C>, F>>>                                                                                                                     
71 | |             ::with_heuristic(model, heur)                                                                                                                                              
   | |____________________________^                                                                                                                                                           
                                                                                                                                                                                              
error: internal compiler error: broken MIR in DefId(0/0:1385 ~ zeta[1bd0]::cp[0]::solver[0]::parallel[0]::{{impl}}[1]::with_search[0]) (const cp::solver::CPSolver::with_heuristic): bad constant user type Canonical { variables: [], value: fn(std::sync::Arc<modeling::Model>, cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<cp::solver::backtracking::copying::CPCopyingSearchNode, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>>, F>) -> cp::solver::parallel::CPParallelSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<<cp::solver::backtracking::copying::CopyingBacktracker as cp::solver::backtracking::Backtracker>::Node, cp::search::core_controllers::DFSController<<cp::solver::backtracking::copying::CopyingBacktracker as cp::solver::backtracking::Backtracker>::Node>>>, F>> {<cp::solver::parallel::CPParallelSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<<cp::solver::backtracking::copying::CopyingBacktracker as cp::solver::backtracking::Backtracker>::Node, cp::search::core_controllers::DFSController<<cp::solver::backtracking::copying::CopyingBacktracker as cp::solver::backtracking::Backtracker>::Node>>>, F>> as cp::solver::CPSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<cp::solver::backtracking::copying::CPCopyingSearchNode, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>>, F>>>::with_heuristic} } vs fn(std::sync::Arc<modeling::Model>, cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<cp::solver::backtracking::copying::CPCopyingSearchNode, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>>, F>) -> cp::solver::parallel::CPParallelSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<cp::solver::backtracking::copying::CPCopyingSearchNode, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>>, F>> {<cp::solver::parallel::CPParallelSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<cp::solver::backtracking::copying::CPCopyingSearchNode, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>>, F>> as cp::solver::CPSolver<cp::search::builder::CustomSearchFactory<cp::solver::kernel::worker::CPWorker<cp::solver::backtracking::copying::CopyingBacktracker, cp::search::core_controllers::ParallelAdapter<cp::solver::backtracking::copying::CPCopyingSearchNode, cp::search::core_controllers::DFSController<cp::solver::backtracking::copying::CPCopyingSearchNode>>>, F>>>::with_heuristic}: NoSolution
  --> src/cp/solver/parallel.rs:76:9                                                                                                                                                          
   |                                                                                                                                                                                          
76 | /         <Self as CPSolver<CustomSearchFactory<CPWorker<B, C>, F>>>                                                                                                                     
77 | |             ::with_heuristic(model, heur)                                                                                                                                              
   | |____________________________^                                                                                                                                                           
                                                                                                                                                                                              
thread 'main' panicked at 'no errors encountered even though `delay_span_bug` issued', librustc_errors/lib.rs:322:17                                                                          
note: Run with `RUST_BACKTRACE=1` for a backtrace.                                                                                                                                            
                                                                                                                                                                                              
error: internal compiler error: unexpected panic                                                                                                                                              
                                                                                                                                                                                              
note: the compiler unexpectedly panicked. this is a bug.                                                                                                                                      
                                                                                                                                                                                              
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports                                                                             
                                                                                                                                                                                              
note: rustc 1.30.1 (1433507eb 2018-11-07) running on x86_64-unknown-linux-gnu                                                                                                                 
                                                                                                                                                                                              
note: compiler flags: -C opt-level=3 --crate-type lib                                                                                                                                         
                                                                                                                                                                                              
note: some of the compiler flags provided by cargo are hidden 

[pietroalbini]

Uh, this looks like a regression. What's the library?

[daniel-fontaine]

It's currently a private library. It's a constraint programming solver. Dan

…

On Sat, Nov 10, 2018, 4:55 PM Pietro Albini ***@***.***> wrote: Uh, this looks like a regression. What's the library? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#55846 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AX1QPYIWAd_cCVaq_E0bfvmPXgBK4FYvks5ut0tagaJpZM4YX-37> .

[pietroalbini]

Can you reduce the bug to a subset of the library you can publish? Unfortunately it's hard for us to investigate an error without the code that's causing it.

cc @rust-lang/compiler

[daniel-fontaine]

Yes, I'll try later today. Thanks.

…

On Sat, Nov 10, 2018, 5:10 PM Pietro Albini ***@***.***> wrote: Can you reduce the bug to a subset of the library you can publish? Unfortunately it's hard for us to investigate an error without the code that's causing it. cc @rust-lang/compiler <https://github.com/orgs/rust-lang/teams/compiler> — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#55846 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AX1QPSag6a2c_7m3ABfbY93m7TbSjcPSks5ut07ggaJpZM4YX-37> .

[eddyb]

@nikomatsakis @oli-obk This looks like either trait system or const-evaluation.

[daniel-fontaine]

Here is a single file example where it occurs. Dan

…

On Sat, Nov 10, 2018 at 5:10 PM Pietro Albini ***@***.***> wrote: Can you reduce the bug to a subset of the library you can publish? Unfortunately it's hard for us to investigate an error without the code that's causing it. cc @rust-lang/compiler <https://github.com/orgs/rust-lang/teams/compiler> — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#55846 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AX1QPSag6a2c_7m3ABfbY93m7TbSjcPSks5ut07ggaJpZM4YX-37> .

[daniel-fontaine]

Below is a rust file with the error.

compiler_error.txt

[estebank]

No longer repros in beta or nightly, present in stable. Would it be reasonable to backport the fix (once we identify it) to stable?

[pnkfelix]

Identifying the nightly where this was fixed via bissection would be a good start to determining what fixed it (and thus evaluating whether a backport to stable is reasonable). But a problem has to meet a pretty high bar to justify a backport to the stable channel... a rare ICE may not cut it