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

[varkor]

This is now fixed, but we need to make sure it won't regress in the future. Currently the test case is quite large: #55846 (comment). If someone wants to fix this, you just need to try to find the smallest test case you can that still fails on the current version of stable and add it to the test suite in src/test/ui.

[pnkfelix]

triage. Since this fixed and just needs a test, tagging as P-medium.