PoC: implement core::panic::panic_error #1

yaahc · 2022-01-06T21:38:15Z

This is a proof of concept for integrating the new core::error::Error trait into the panic runtime. This will eventually evolve into a full proposal and possibly RFC, but for now it is quick and dirty just to test the core concepts and the shape of the API so I can share it with other project members and discuss the design prior to refinement.

yaahc · 2022-01-06T21:39:13Z

library/core/src/panic/panic_info.rs

+            PayloadKind::Any(payload) => payload.downcast_ref(),
+            #[cfg(not(bootstrap))]
+            PayloadKind::Error(_) => None,
+            // PayloadKind::Error(error) => error.downcast_ref(),


I kinda wanted to let this downcast for either but there isn't any reason to do so. I'd likely have to internally reimplement the downcast_ref logic to avoid needing to add T: Error.

yaahc · 2022-01-06T21:41:05Z

library/core/src/panic/panic_info.rs

+    #[inline]
+    #[cfg(not(bootstrap))]
+    pub fn error_constructor(
+        // message: Option<&'a fmt::Arguments<'a>>,


This will likely need a message as well, so that unwrap and expect can provide their message when panicking as an error. My plan is to change the error() method on PanicInfo to be called source, and to treat the message like the outermost error in the chain of errors.

yaahc · 2022-01-06T21:41:30Z

library/core/src/panic/panic_info.rs

+        match self.payload {
+            PayloadKind::Any(payload) => payload,
+            #[cfg(not(bootstrap))]
+            PayloadKind::Error(_) => &HackerVoice, // I'm in


I will not apologize

yaahc · 2022-01-06T21:42:50Z

library/std/src/panicking.rs

@@ -196,6 +196,8 @@ fn default_hook(info: &PanicInfo<'_>) {
        Some(s) => *s,
        None => match info.payload().downcast_ref::<String>() {
            Some(s) => &s[..],
+            #[cfg(not(bootstrap))]
+            None if info.error().is_some() => "non-recoverable runtime Error",


Once std::error::Report is merged this will be updated to actually report the source error when one exists, rather than requiring the user installs a custom hook that actually prints the error.

yaahc · 2022-01-06T21:44:07Z

library/std/src/panicking.rs

+    let loc = info.location().unwrap(); // The current implementation always returns Some
+    if let Some(error) = info.error() {
+        crate::sys_common::backtrace::__rust_end_short_backtrace(move || {
+            rust_panic_error_with_hook(error, loc);
+        })
+    } else {
+        let msg = info.message().unwrap(); // The current implementation always returns Some
+        crate::sys_common::backtrace::__rust_end_short_backtrace(move || {
+            if let Some(msg) = msg.as_str() {
+                rust_panic_with_hook(&mut StrPanicPayload(msg), info.message(), loc);
+            } else {
+                rust_panic_with_hook(&mut PanicPayload::new(msg), info.message(), loc);
+            }
+        })
+    }


I assume this is to help make the types for the msg more uniform so we can downcast to them more consistently, but I really do not like that this is creating a new PanicInfo when we already have one...

yaahc · 2022-01-06T21:47:31Z

library/std/src/panicking.rs

+        }
+    }
+
+    rust_panic(&mut ErrorPanicPayload)


Ideally it should be possible to panic with no payload at all. My intuition is that propagating the error with an unwinding panic to be caught and potentially reacted to is an anti-pattern, since converting a dyn Error to a panic semantically represents promoting a recoverable error to a non-recoverable error. I'm interested in hearing real world usecases of propagating and handling payloads via panics and am open to the possibility that I'm making the wrong call here, but my expectation is that if you need to react to an error in a panic it should never have been a panic in the first place.

For now we make a dummy payload that shouldn't need to allocate and which only indicates that the current panic started as a dyn Error.

author Preston From <prestonfrom@gmail.com> 1645164142 -0600 committer Preston From <prestonfrom@gmail.com> 1650005351 -0600

…res, r=oli-obk Tell users not to file a bug when using internal library features Actually fixes rust-lang#97501. I don't think we should suppress the suggestion to add `#![feature(..)]`, though I guess I could be convinced otherwise. r? `@Nilstrieb` cc `@RalfJung` Didn't add a test b/c I don't think we test this for lang features either, but I can confirm it does work. ``` warning: the feature `core_intrinsics` is internal to the compiler or standard library --> /home/michael/test.rs:1:12 | 1 | #![feature(core_intrinsics)] | ^^^^^^^^^^^^^^^ | = note: using it is strongly discouraged = note: `#[warn(internal_features)]` on by default thread 'rustc' panicked at compiler/rustc_mir_transform/src/validate.rs:94:25: broken MIR in Item(DefId(0:6 ~ test[42db]::{impl#0}::add)) (after phase change to runtime-optimized) at bb0[0]: Cannot perform arithmetic Add on type WrapInt8 stack backtrace: 0: begin_panic_handler at ./library/std/src/panicking.rs:665:5 1: panic_fmt at ./library/core/src/panicking.rs:74:14 2: fail<alloc::string::String> at ./compiler/rustc_mir_transform/src/validate.rs:146:9 3: run_pass at ./compiler/rustc_mir_transform/src/validate.rs:94:13 4: validate_body at ./compiler/rustc_mir_transform/src/pass_manager.rs:193:5 5: run_passes_inner at ./compiler/rustc_mir_transform/src/pass_manager.rs:176:13 6: rustc_mir_transform::pass_manager::run_passes at ./compiler/rustc_mir_transform/src/pass_manager.rs:87:5 7: run_optimization_passes at ./compiler/rustc_mir_transform/src/lib.rs:561:5 8: inner_optimized_mir at ./compiler/rustc_mir_transform/src/lib.rs:667:5 9: optimized_mir at ./compiler/rustc_mir_transform/src/lib.rs:630:21 10: {closure#0} at ./compiler/rustc_query_impl/src/plumbing.rs:285:13 [... omitted 22 frames ...] 11: query_get_at<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 8]>>> at ./compiler/rustc_middle/src/query/plumbing.rs:145:17 12: instance_mir 13: collect_items_of_instance at ./compiler/rustc_monomorphize/src/collector.rs:1203:16 14: {closure#0} at ./compiler/rustc_monomorphize/src/collector.rs:447:17 15: maybe_grow<(), rustc_monomorphize::collector::collect_items_rec::{closure_env#0}> at /home/michael/.cargo/registry/src/index.crates.io-6f17d22bba15001f/stacker-0.1.15/src/lib.rs:55:9 16: ensure_sufficient_stack<(), rustc_monomorphize::collector::collect_items_rec::{closure_env#0}> at ./compiler/rustc_data_structures/src/stack.rs:17:5 17: collect_items_rec at ./compiler/rustc_monomorphize/src/collector.rs:446:13 18: collect_items_rec at ./compiler/rustc_monomorphize/src/collector.rs:526:13 19: {closure#0} at ./compiler/rustc_monomorphize/src/collector.rs:1597:17 20: {closure#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}> at ./compiler/rustc_data_structures/src/sync/parallel.rs:182:34 21: call_once<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#0}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>> at ./library/core/src/panic/unwind_safe.rs:272:9 22: do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#0}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>, ()> at ./library/std/src/panicking.rs:557:40 23: try<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#0}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>> at ./library/std/src/panicking.rs:521:19 24: run<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#1}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>> at ./compiler/rustc_data_structures/src/sync/parallel.rs:28:9 25: {closure#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}> at ./compiler/rustc_data_structures/src/sync/parallel.rs:186:21 26: {closure#0}<rustc_middle::mir::mono::MonoItem, rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure_env#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>> at ./library/core/src/iter/traits/iterator.rs:815:29 27: fold<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global, (), core::iter::traits::iterator::Iterator::for_each::call::{closure_env#0}<rustc_middle::mir::mono::MonoItem, rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure_env#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>> at ./library/alloc/src/vec/into_iter.rs:317:25 28: for_each<alloc::vec::into_iter::IntoIter<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure_env#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>> at ./library/core/src/iter/traits/iterator.rs:818:9 29: {closure#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}> at ./compiler/rustc_data_structures/src/sync/parallel.rs:185:17 30: parallel_guard<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>> at ./compiler/rustc_data_structures/src/sync/parallel.rs:44:15 31: par_for_each_in<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}> at ./compiler/rustc_data_structures/src/sync/parallel.rs:178:9 32: {closure#1} at ./compiler/rustc_monomorphize/src/collector.rs:1595:13 33: run<(), rustc_monomorphize::collector::collect_crate_mono_items::{closure_env#1}> at ./compiler/rustc_data_structures/src/profiling.rs:754:9 34: time<(), rustc_monomorphize::collector::collect_crate_mono_items::{closure_env#1}> at ./compiler/rustc_session/src/utils.rs:16:9 35: collect_crate_mono_items at ./compiler/rustc_monomorphize/src/collector.rs:1594:9 36: collect_and_partition_mono_items at ./compiler/rustc_monomorphize/src/partitioning.rs:1124:30 37: {closure#0} at ./compiler/rustc_query_impl/src/plumbing.rs:281:9 [... omitted 22 frames ...] 38: query_get_at<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 24]>>> at ./compiler/rustc_middle/src/query/plumbing.rs:145:17 39: collect_and_partition_mono_items at ./compiler/rustc_middle/src/query/plumbing.rs:423:31 40: collect_and_partition_mono_items at ./compiler/rustc_middle/src/query/plumbing.rs:414:17 41: codegen_crate<rustc_codegen_llvm::LlvmCodegenBackend> at ./compiler/rustc_codegen_ssa/src/base.rs:596:25 42: codegen_crate at ./compiler/rustc_codegen_llvm/src/lib.rs:361:18 43: {closure#0} at ./compiler/rustc_interface/src/passes.rs:1027:9 44: run<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}> at ./compiler/rustc_data_structures/src/profiling.rs:754:9 45: time<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}> at ./compiler/rustc_session/src/utils.rs:16:9 46: start_codegen at ./compiler/rustc_interface/src/passes.rs:1026:19 47: codegen_and_build_linker at ./compiler/rustc_interface/src/queries.rs:128:31 48: {closure#6} at ./compiler/rustc_driver_impl/src/lib.rs:451:25 49: {closure#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>> at ./compiler/rustc_middle/src/ty/context.rs:1336:37 50: {closure#0}<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>> at ./compiler/rustc_middle/src/ty/context/tls.rs:82:9 51: try_with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>> at ./library/std/src/thread/local.rs:283:12 52: with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>> at ./library/std/src/thread/local.rs:260:9 53: enter_context<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>> at ./compiler/rustc_middle/src/ty/context/tls.rs:79:5 54: enter<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>> at ./compiler/rustc_middle/src/ty/context.rs:1336:9 55: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#6}> at ./compiler/rustc_interface/src/queries.rs:64:9 56: {closure#1} at ./compiler/rustc_driver_impl/src/lib.rs:450:13 57: enter<rustc_driver_impl::run_compiler::{closure#0}::{closure_env#1}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>> at ./compiler/rustc_interface/src/queries.rs:209:19 58: {closure#0} at ./compiler/rustc_driver_impl/src/lib.rs:388:22 59: {closure#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}> at ./compiler/rustc_interface/src/interface.rs:502:27 60: {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>> at ./compiler/rustc_interface/src/util.rs:154:13 61: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>> at ./compiler/rustc_interface/src/util.rs:106:21 62: set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>> at /home/michael/.cargo/registry/src/index.crates.io-6f17d22bba15001f/scoped-tls-1.0.1/src/lib.rs:137:9 63: create_session_globals_then<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>>> at ./compiler/rustc_span/src/lib.rs:134:5 64: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>> at ./compiler/rustc_interface/src/util.rs:105:17 note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace. error: the compiler unexpectedly panicked. this is a bug. note: using internal features is not supported and expected to cause internal compiler errors when used incorrectly note: rustc 1.82.0-dev running on x86_64-unknown-linux-gnu query stack during panic: #0 [optimized_mir] optimizing MIR for `<impl at /home/michael/test.rs:9:1: 9:32>::add` #1 [collect_and_partition_mono_items] collect_and_partition_mono_items end of query stack ```

PoC: implement core::panic::panic_error

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yaahc commented Jan 6, 2022

View reviewed changes

yaahc mentioned this pull request Jan 18, 2022

Add provide_any module to core rust-lang/rfcs#3192

Merged

bstrie mentioned this pull request Jan 19, 2022

Proposal: use anyhow crate and pass extra context to error messages enarx/enarx#726

Closed

yaahc mentioned this pull request Feb 9, 2022

RFC: Backtrace in core rust-lang/rfcs#3156

Closed

4 tasks

yaahc mentioned this pull request Feb 18, 2022

Start working on proof of concept for exposing Backtrace in core rust-lang/rust#77384

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yaahc pushed a commit that referenced this pull request May 17, 2022

Lint for significant drops who may have surprising lifetimes #1

d9e963f

author Preston From <prestonfrom@gmail.com> 1645164142 -0600 committer Preston From <prestonfrom@gmail.com> 1650005351 -0600

yaahc closed this Jul 18, 2022

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PoC: implement core::panic::panic_error #1

PoC: implement core::panic::panic_error #1

yaahc commented Jan 6, 2022

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PoC: implement core::panic::panic_error #1

PoC: implement core::panic::panic_error #1

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