ICE on invalid input: `fn f(){;` #74120

xobs · 2020-07-07T03:20:09Z

Code

extern "C" {
    fn f(){;
    fn g();
}

Error output

   Compiling playground v0.0.1 (/playground)
error: this file contains an unclosed delimiter
 --> src/lib.rs:4:3
  |
1 | extern "C" {
  |            - unclosed delimiter
2 |     fn f(){;
  |           - this delimiter might not be properly closed...
3 |     fn g();
4 | }
  | - ^
  | |
  | ...as it matches this but it has different indentation

error: incorrect function inside `extern` block
 --> src/lib.rs:2:8
  |
1 |   extern "C" {
  |   ---------- `extern` blocks define existing foreign functions and functions inside of them cannot have a body
2 |       fn f(){;
  |  ________^__-
  | |        |
  | |        cannot have a body
3 | |     fn g();
4 | | }
  | |_- help: remove the invalid body: `;`
  |
  = help: you might have meant to write a function accessible through FFI, which can be done by writing `extern fn` outside of the `extern` block
  = note: for more information, visit https://doc.rust-lang.org/std/keyword.extern.html

error: free function without a body
 --> src/lib.rs:3:5
  |
3 |     fn g();
  |     ^^^^^^-
  |           |
  |           help: provide a definition for the function: `{ <body> }`

warning: unnecessary trailing semicolon
 --> src/lib.rs:2:12
  |
2 |     fn f(){;
  |            ^ help: remove this semicolon
  |
  = note: `#[warn(redundant_semicolons)]` on by default

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/librustc_middle/hir/map/collector.rs:155:31
note: run with `RUST_BACKTRACE=1` environment variable to display 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 1.44.1 (c7087fe00 2020-06-17) running on x86_64-unknown-linux-gnu

note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type lib

note: some of the compiler flags provided by cargo are hidden

error: aborting due to 3 previous errors; 1 warning emitted

error: could not compile `playground`.

To learn more, run the command again with --verbose.

Backtrace

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src\librustc_middle\hir\map\collector.rs:155:31
stack backtrace:
   0:     0x7fff11089bdf - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h72e337a2cec56afc
   1:     0x7fff110b747b - core::fmt::write::h301a11378dba5c10
   2:     0x7fff1107a3ac - <std::io::IoSliceMut as core::fmt::Debug>::fmt::h9e4d180d084072c2
   3:     0x7fff1108f1fc - std::panicking::take_hook::h1017141a1333a573
   4:     0x7fff1108ee3f - std::panicking::take_hook::h1017141a1333a573
   5:     0x7ffeb1e9d61a - rustc_driver::report_ice::h3f0dba12da2a5809
   6:     0x7fff1108fa98 - std::panicking::rust_panic_with_hook::h43d41cd5d682c22d
   7:     0x7fff1108f5ef - rust_begin_unwind
   8:     0x7fff110b3ed0 - core::panicking::panic_fmt::h7623003454911b6c
   9:     0x7fff110b3e1c - core::panicking::panic::hb5a07a26965dd7fe
  10:     0x7ffeb578da46 - ZN12rustc_middle2ty111_DERIVE_rustc_data_structures_stable_hasher_HashStable_rustc_middle_ich_StableHashingContext_ctx_FOR_SymbolName159_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc_middle..ich..hcx..StableHashingContext$GT$$u20$
  11:     0x7ffeb57bdd69 - <rustc_middle::hir::map::Map as rustc_hir::intravisit::Map>::impl_item::h29a5725cef6a6bc2
  12:     0x7ffeb56476e6 - rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::debug_node::ha0b2381c3958984f
  13:     0x7ffeb5ac3f6e - <rustc_middle::ty::sty::TypeAndMut as core::fmt::Debug>::fmt::h14510a0c43efcc1f
  14:     0x7ffeb5a111aa - <rustc_middle::ty::sty::TypeAndMut as core::fmt::Debug>::fmt::h14510a0c43efcc1f
  15:     0x7ffeb56c7a01 - <rustc_middle::ty::cast::CastKind as core::fmt::Debug>::fmt::h90b142d735531df6
  16:     0x7ffeb56476e6 - rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::debug_node::ha0b2381c3958984f
  17:     0x7ffeb5ab16ad - <rustc_middle::ty::sty::TypeAndMut as core::fmt::Debug>::fmt::h14510a0c43efcc1f
  18:     0x7ffeb59e634e - <rustc_middle::ty::sty::TypeAndMut as core::fmt::Debug>::fmt::h14510a0c43efcc1f
  19:     0x7ffeb57bb305 - rustc_middle::hir::map::Map::expect_item::h4affa69e9dd72ff8
  20:     0x7ffeb463f102 - <rustc_passes::upvars::CaptureCollector as rustc_hir::intravisit::Visitor>::visit_expr::hd6e55112cd082a96
  21:     0x7ffeb45b2994 - rustc_passes::hir_id_validator::check_crate::hc754549cd5db125d
  22:     0x7ffeb2198782 - rustc_interface::passes::QueryContext::print_stats::h6d9e7b3318b13f88
  23:     0x7ffeb1eb265b - rustc_errors::snippet::MultilineAnnotation::increase_depth::hc7cbc289ff11bb9b
  24:     0x7ffeb202abb6 - rustc_driver::pretty::print_after_hir_lowering::h0533888ff42872ae
  25:     0x7ffeb2017a43 - rustc_driver::pretty::print_after_hir_lowering::h0533888ff42872ae
  26:     0x7ffeb1eb7192 - rustc_errors::snippet::MultilineAnnotation::increase_depth::hc7cbc289ff11bb9b
  27:     0x7ffeb205976e - rustc_driver::pretty::print_after_hir_lowering::h0533888ff42872ae
  28:     0x7ffeb202cccd - rustc_driver::pretty::print_after_hir_lowering::h0533888ff42872ae
  29:     0x7ffeb1ea647e - <rustc_middle::ty::instance::InstanceDef as rustc_middle::ty::query::keys::Key>::query_crate::hfbc139b7b5e8d887
  30:     0x7ffeb1ea3099 - <rustc_middle::ty::instance::InstanceDef as rustc_middle::ty::query::keys::Key>::query_crate::hfbc139b7b5e8d887
  31:     0x7ffeb1eab934 - rustc_errors::snippet::MultilineAnnotation::increase_depth::hc7cbc289ff11bb9b
  32:     0x7ffeb2031193 - rustc_driver::pretty::print_after_hir_lowering::h0533888ff42872ae
  33:     0x7fff1109f222 - std::sys::windows::thread::Thread::new::he0eea534f2b6df4d
  34:     0x7fff4f357bd4 - BaseThreadInitThunk
  35:     0x7fff4f64ce51 - RtlUserThreadStart

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 1.44.1 (c7087fe00 2020-06-17) running on x86_64-pc-windows-msvc

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [index_hir] index HIR
#1 [hir_owner] HIR owner of `{{misc}}#0`
#2 [analysis] running analysis passes on this crate
end of query stack

This issue has been assigned to @ayazhafiz via this comment.

The text was updated successfully, but these errors were encountered:

ratijas · 2020-07-07T14:26:08Z

Semicolon is not the main problem here. Standalone semicolons are allowed as items inside function body.

Second function definition fn g(); would be OK if not for the extern "C" block — AFAIK only function declarations are allowed there, so fn f() {..} is not valid syntax.

spastorino · 2020-07-07T22:25:12Z

Prioritized as P-medium as per Zulip discussion

ayazhafiz · 2020-07-08T03:45:17Z

@rustbot claim

ayazhafiz · 2020-07-10T02:22:55Z

A possibly clearer repro: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=40cd60c27e0927eba22d2e9667f091e2

extern "C" {
    fn f() {
        fn g() {}
    }
}

JohnTitor · 2020-07-27T13:53:15Z

The previous issue has been fixed, let's try again (sorry for the noise!).
@rustbot glacier "https://gist.github.com/fa3a4448239b08769f0c581dd1588f36"

Don't visit foreign function bodies when lowering ast to hir Previously the existence of bodies inside a foreign function block would cause a panic in the hir `NodeCollector` during its collection of crate bodies to compute a crate hash: https://github.com/rust-lang/rust/blob/e59b08e62ea691916d2f063cac5aab4634128022/src/librustc_middle/hir/map/collector.rs#L154-L158 The collector walks the hir tree and creates a map of hir nodes, then attaching bodies in the crate to their owner in the map. For a code like ```rust extern "C" { fn f() { fn g() {} } } ``` The crate bodies include the body of the function `g`. But foreign functions cannot have bodies, and while the parser AST permits a foreign function to have a body, the hir doesn't. This means that the body of `f` is not present in the hir, and so neither is `g`. So when the `NodeCollector` finishes the walking the hir, it has no record of `g`, cannot find an owner for the body of `g` it sees in the crate bodies, and blows up. Why do the crate bodies include the body of `g`? The AST walker has a need a for walking function bodies, and FFIs share the same AST node as functions in other contexts. There are at least two options to fix this: - Don't unwrap the map entry for an hir node in the `NodeCollector` - Modifier the ast->hir lowering visitor to ignore foreign function blocks I don't think the first is preferrable, since we want to know when we can't find a body for an hir node that we thought had one (dropping this information may lead to an invalid hash). So this commit implements the second option. Closes rust-lang#74120

xobs added 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. labels Jul 7, 2020

jonas-schievink added A-HIR Area: The high-level intermediate representation (HIR) I-prioritize Issue: Indicates that prioritization has been requested for this issue. labels Jul 7, 2020

spastorino added P-medium Medium priority and removed I-prioritize Issue: Indicates that prioritization has been requested for this issue. labels Jul 7, 2020

rustbot self-assigned this Jul 8, 2020

ayazhafiz mentioned this issue Jul 10, 2020

Don't visit foreign function bodies when lowering ast to hir #74204

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JohnTitor mentioned this issue Jul 25, 2020

Automatically add a testcase via a comment rust-lang/glacier#231

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bors closed this as completed in 2303939 Aug 16, 2020

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Uh oh!

ICE on invalid input: `fn f(){;` #74120

ICE on invalid input: `fn f(){;` #74120

xobs commented Jul 7, 2020 •

edited by rustbot

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ratijas commented Jul 7, 2020

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ayazhafiz commented Jul 8, 2020

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JohnTitor commented Jul 27, 2020

Uh oh!

ICE on invalid input: fn f(){; #74120

ICE on invalid input: fn f(){; #74120

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ratijas commented Jul 7, 2020

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ayazhafiz commented Jul 8, 2020

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JohnTitor commented Jul 27, 2020

Uh oh!

ICE on invalid input: `fn f(){;` #74120

ICE on invalid input: `fn f(){;` #74120

xobs commented Jul 7, 2020 •

edited by rustbot

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