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ICE with static and const_fn #47971

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ghost opened this issue Feb 2, 2018 · 1 comment · Fixed by #46882
Closed

ICE with static and const_fn #47971

ghost opened this issue Feb 2, 2018 · 1 comment · Fixed by #46882
Labels
A-MIR Area: Mid-level IR (MIR) - https://blog.rust-lang.org/2016/04/19/MIR.html C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@ghost
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ghost commented Feb 2, 2018

when initalizing a static using a const_fn that returns a pointer to the interior of the static, rustc panics.

#![feature(const_fn)]

struct S(pub &'static u32, pub u32);

const fn g(ss: &S) -> &u32 { &ss.1 }

static s: S = S(g(&s), 0);

fn main () { }

instead of s being initialized with a reference to its interior, the compiler panics:

error: internal compiler error: librustc_trans/mir/constant.rs:232: loading from `static` (({ i32*, i32 }*:@_ZN3foo1s17h92f76ce7d8965747E = internal global { i32*, i32 })) in constant
 --> foo.rs:5:30
  |
5 | const fn g(ss: &S) -> &u32 { &ss.1 }
  |                              ^^^^^

thread 'rustc' panicked at 'Box<Any>', librustc_errors/lib.rs:482:9
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at libstd/sys_common/backtrace.rs:71
             at libstd/sys_common/backtrace.rs:59
   2: std::panicking::default_hook::{{closure}}
             at libstd/panicking.rs:380
   3: std::panicking::default_hook
             at libstd/panicking.rs:396
   4: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:576
   5: std::panicking::begin_panic
   6: rustc_errors::Handler::span_bug
   7: <std::thread::local::LocalKey<T>>::with
   8: rustc::ty::context::tls::with_opt
   9: rustc::session::span_bug_fmt
  10: rustc_trans::mir::constant::MirConstContext::const_place
  11: rustc_trans::mir::constant::MirConstContext::trans
  12: rustc_trans::mir::constant::MirConstContext::trans_def
  13: rustc_trans::mir::constant::MirConstContext::trans
  14: rustc_trans::mir::constant::MirConstContext::trans_def
  15: rustc_trans::consts::trans_static
  16: rustc_trans::trans_item::MonoItemExt::define
  17: rustc_trans::base::compile_codegen_unit
  18: rustc::ty::maps::<impl rustc::ty::maps::queries::compile_codegen_unit<'tcx>>::compute_result
  19: rustc::dep_graph::graph::DepGraph::with_task_impl
  20: rustc_errors::Handler::track_diagnostics
  21: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::cycle_check
  22: rustc::ty::maps::<impl rustc::ty::maps::queries::compile_codegen_unit<'tcx>>::force
  23: rustc::ty::maps::<impl rustc::ty::maps::queries::compile_codegen_unit<'tcx>>::try_get
  24: rustc::ty::maps::TyCtxtAt::compile_codegen_unit
  25: rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::compile_codegen_unit
  26: rustc_trans::base::trans_crate
  27: <rustc_trans::LlvmTransCrate as rustc_trans_utils::trans_crate::TransCrate>::trans_crate
  28: rustc::util::common::time
  29: rustc_driver::driver::phase_4_translate_to_llvm
  30: rustc_driver::driver::compile_input::{{closure}}
  31: <std::thread::local::LocalKey<T>>::with
  32: <std::thread::local::LocalKey<T>>::with
  33: rustc::ty::context::TyCtxt::create_and_enter
  34: rustc_driver::driver::compile_input
  35: rustc_driver::run_compiler

rustc --version --verbose:

rustc 1.25.0-nightly (56733bc9f 2018-02-01)
binary: rustc
commit-hash: 56733bc9f8302409a2b6110f422512923c878154
commit-date: 2018-02-01
host: x86_64-unknown-linux-gnu
release: 1.25.0-nightly
LLVM version: 4.0
@cuviper cuviper added I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. A-MIR Area: Mid-level IR (MIR) - https://blog.rust-lang.org/2016/04/19/MIR.html C-bug Category: This is a bug. labels Feb 2, 2018
@oli-obk
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oli-obk commented Feb 5, 2018

Will probably be fixed by #46882

bors added a commit that referenced this issue Feb 6, 2018
Replace all const evaluation with miri

* error reporting in constants prints a stacktrace through all called const fns
* Trivial constant propagation and folding in MIR (always active, irrelevant of the optimization level)
* can now use floating constants in patterns (previously only floating point literals were allowed)
    * the future compat lint is still produced for both cases
* can index into constant arrays during const eval (previously feature gated)
* can create a constant union value with field `a` and read from field `b`
* can dereference references into constants
* can create references inside constants (`const X: &u32 = &22`)
* Tuple struct constructors can be used in constants
* regression in const eval errors spans (some of these need improvements in mir debug info)
* can cast floats to ints and vice versa (in constants, and even nan/inf constants)
* Mir dump prints false/true instead of 0u8/1u8
* `1i8 >> [8][0]` does not lint about exceeding bitshifts anymore.
    * Needs const propagation across projections
* `foo[I]` produces a const eval lint if `foo: [T; N]` and `N < I`
    * Essentially all builtin panics produce lints if they can be statically proven to trigger at runtime. This is on a best effort basis, so there might be some complex cases that don't trigger. (The runtime panic stays there, irrelevant of whether the lint is produced or not)
* can use `union`s to implement `transmute` for `Copy` types in constants without a feature gate. With all the greatness and nasal demons that come with this.

fixes #34997 (stack overflow with many constants)
fixes #25574 (deref byte strings in patterns)
fixes #27918 (broken mir ICE)
fixes #46114 (ICE on struct constructors in patterns)
fixes #37448 (`SomeStruct { foo } as SomeStruct`)
fixes #43754 (`return` in const fn)
fixes #41898 (tuple struct constructors)
fixes #31364 (infinite recursion with const fn, fixed by miri's recursion limit)
closes #29947 (const indexing stabilization)
fixes #45044 (pattern matching repeat expressions)
fixes #47971 (ICE on const fn + references)

r? @eddyb
bors added a commit that referenced this issue Mar 7, 2018
Replace all const evaluation with miri

* error reporting in constants prints a stacktrace through all called const fns
* Trivial constant propagation and folding in MIR (always active, irrelevant of the optimization level)
* can now use floating constants in patterns (previously only floating point literals were allowed)
    * the future compat lint is still produced for both cases
* can index into constant arrays during const eval (previously feature gated)
* can create a constant union value with field `a` and read from field `b`
* can dereference references into constants
* can create references inside constants (`const X: &u32 = &22`)
* Tuple struct constructors can be used in constants
* regression in const eval errors spans (some of these need improvements in mir debug info)
* can cast floats to ints and vice versa (in constants, and even nan/inf constants)
* Mir dump prints false/true instead of 0u8/1u8
* `1i8 >> [8][0]` does not lint about exceeding bitshifts anymore.
    * Needs const propagation across projections
* `foo[I]` produces a const eval lint if `foo: [T; N]` and `N < I`
    * Essentially all builtin panics produce lints if they can be statically proven to trigger at runtime. This is on a best effort basis, so there might be some complex cases that don't trigger. (The runtime panic stays there, irrelevant of whether the lint is produced or not)
* can use `union`s to implement `transmute` for `Copy` types in constants without a feature gate. With all the greatness and nasal demons that come with this.
* can convert integers to `&'static T` in constants (useful for embedded)

fixes #34997 (stack overflow with many constants)
fixes #25574 (deref byte strings in patterns)
fixes #27918 (broken mir ICE)
fixes #46114 (ICE on struct constructors in patterns)
fixes #37448 (`SomeStruct { foo } as SomeStruct`)
fixes #43754 (`return` in const fn)
fixes #41898 (tuple struct constructors)
fixes #31364 (infinite recursion with const fn, fixed by miri's recursion limit)
closes #29947 (const indexing stabilization)
fixes #45044 (pattern matching repeat expressions)
fixes #47971 (ICE on const fn + references)
fixes #48081 (ICE on cyclic assoc const error)
fixes #48746 (nonhelpful error message with unions)

r? @eddyb

even though 1k loc are added in tests, this PR reduces the loc in this repository by 700
bors added a commit that referenced this issue Mar 8, 2018
Replace all const evaluation with miri

* error reporting in constants prints a stacktrace through all called const fns
* Trivial constant propagation and folding in MIR (always active, irrelevant of the optimization level)
* can now use floating constants in patterns (previously only floating point literals were allowed)
    * the future compat lint is still produced for both cases
* can index into constant arrays during const eval (previously feature gated)
* can create a constant union value with field `a` and read from field `b`
* can dereference references into constants
* can create references inside constants (`const X: &u32 = &22`)
* Tuple struct constructors can be used in constants
* regression in const eval errors spans (some of these need improvements in mir debug info)
* can cast floats to ints and vice versa (in constants, and even nan/inf constants)
* Mir dump prints false/true instead of 0u8/1u8
* `1i8 >> [8][0]` does not lint about exceeding bitshifts anymore.
    * Needs const propagation across projections
* `foo[I]` produces a const eval lint if `foo: [T; N]` and `N < I`
    * Essentially all builtin panics produce lints if they can be statically proven to trigger at runtime. This is on a best effort basis, so there might be some complex cases that don't trigger. (The runtime panic stays there, irrelevant of whether the lint is produced or not)
* can use `union`s to implement `transmute` for `Copy` types in constants without a feature gate. With all the greatness and nasal demons that come with this.
* can convert integers to `&'static T` in constants (useful for embedded)

fixes #34997 (stack overflow with many constants)
fixes #25574 (deref byte strings in patterns)
fixes #27918 (broken mir ICE)
fixes #46114 (ICE on struct constructors in patterns)
fixes #37448 (`SomeStruct { foo } as SomeStruct`)
fixes #43754 (`return` in const fn)
fixes #41898 (tuple struct constructors)
fixes #31364 (infinite recursion with const fn, fixed by miri's recursion limit)
closes #29947 (const indexing stabilization)
fixes #45044 (pattern matching repeat expressions)
fixes #47971 (ICE on const fn + references)
fixes #48081 (ICE on cyclic assoc const error)
fixes #48746 (nonhelpful error message with unions)

r? @eddyb

even though 1k loc are added in tests, this PR reduces the loc in this repository by 700
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Labels
A-MIR Area: Mid-level IR (MIR) - https://blog.rust-lang.org/2016/04/19/MIR.html C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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