Failure on cargo-ui/unstable-attr/invalid regression

[karkhaz]

I tried running the regression suite just before releasing on an M1 macOS host:

RUST_BACKTRACE=1 ./scripts/kani-regression.sh

using tag 0.30.0, i.e. tip of this PR.

One test failed:

---- [cargo-kani] cargo-ui/unstable-attr/invalid/expected stdout ----

error: test failed: expected output to contain the line(s):
error: failed to parse `#[kani::unstable]`: missing `feature` field
src/lib.rs
|
| #[kani::unstable(
| ^^^^^^^^^^^^^^^^^^
|
= note: expected format: #[kani::unstable(feature="<IDENTIFIER>", issue="<ISSUE>", reason="<DESCRIPTION>")]
= note: this error originates in the attribute macro `kani::unstable` (in Nightly builds, run with -Z macro-backtrace for more info)
status: exit status: 1
command: cd "/private/tmp/kani-0.30.0/tests/cargo-ui/unstable-attr/invalid" && "cargo" "kani" "--target-dir" "/private/tmp/kani-0.30.0/build/tests/cargo-ui/unstable-attr/invalid/expected/target"
stdout:
------------------------------------------
error: failed to parse `#[kani::unstable]`: expected "key = value" pair, but found `feature`
  --> src/lib.rs:17:1
   |
17 | #[kani::unstable(feature, issue)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: expected format: #[kani::unstable(feature="<IDENTIFIER>", issue="<ISSUE>", reason="<DESCRIPTION>")]
   = note: this error originates in the attribute macro `kani::unstable` (in Nightly builds, run with -Z macro-backtrace for more info)

error: internal compiler error: Kani unexpectedly panicked at panicked at 'expected well formed unstable attribute, but found: UnstableAttrParseError { reason: "expected \"key = value\" pair, but found `feature`", attr: Attribute { kind: Normal(NormalAttr { item: AttrItem { path: Path { span: src/lib.rs:17:1: 17:34 (#13), segments: [PathSegment { ident: kanitool#13, id: NodeId(26), args: None }, PathSegment { ident: unstable#13, id: NodeId(27), args: None }], tokens: None }, args: Delimited(DelimArgs { dspan: DelimSpan { open: src/lib.rs:17:1: 17:34 (#13), close: src/lib.rs:17:1: 17:34 (#13) }, delim: Parenthesis, tokens: TokenStream([Token(Token { kind: Ident("feature", false), span: src/lib.rs:17:18: 17:25 (#0) }, Joint), Token(Token { kind: Comma, span: src/lib.rs:17:25: 17:26 (#0) }, Alone), Token(Token { kind: Ident("issue", false), span: src/lib.rs:17:27: 17:32 (#0) }, Alone)]) }), tokens: None }, tokens: None }), id: AttrId(102), style: Outer, span: src/lib.rs:17:1: 17:34 (#13) } }', kani-compiler/src/kani_middle/attributes.rs:154:21.

error: Failed to compile `invalid` due to an internal compiler error.: error: internal compiler error: Kani unexpectedly panicked at panicked at 'expected well formed unstable attribute, but found: UnstableAttrParseError { reason: "expected \"key = value\" pair, but found `feature`", attr: Attribute { kind: Normal(NormalAttr { item: AttrItem { path: Path { span: src/lib.rs:17:1: 17:34 (#13), segments: [PathSegment { ident: kanitool#13, id: NodeId(26), args: None }, PathSegment { ident: unstable#13, id: NodeId(27), args: None }], tokens: None }, args: Delimited(DelimArgs { dspan: DelimSpan { open: src/lib.rs:17:1: 17:34 (#13), close: src/lib.rs:17:1: 17:34 (#13) }, delim: Parenthesis, tokens: TokenStream([Token(Token { kind: Ident("feature", false), span: src/lib.rs:17:18: 17:25 (#0) }, Joint), Token(Token { kind: Comma, span: src/lib.rs:17:25: 17:26 (#0) }, Alone), Token(Token { kind: Ident("issue", false), span: src/lib.rs:17:27: 17:32 (#0) }, Alone)]) }), tokens: None }, tokens: None }), id: AttrId(102), style: Outer, span: src/lib.rs:17:1: 17:34 (#13) } }', kani-compiler/src/kani_middle/attributes.rs:154:21.



------------------------------------------
stderr:
------------------------------------------
   Compiling invalid v0.1.0 (/private/tmp/kani-0.30.0/tests/cargo-ui/unstable-attr/invalid)
thread 'rustc' panicked at 'expected well formed unstable attribute, but found: UnstableAttrParseError { reason: "expected \"key = value\" pair, but found `feature`", attr: Attribute { kind: Normal(NormalAttr { item: AttrItem { path: Path { span: src/lib.rs:17:1: 17:34 (#13), segments: [PathSegment { ident: kanitool#13, id: NodeId(26), args: None }, PathSegment { ident: unstable#13, id: NodeId(27), args: None }], tokens: None }, args: Delimited(DelimArgs { dspan: DelimSpan { open: src/lib.rs:17:1: 17:34 (#13), close: src/lib.rs:17:1: 17:34 (#13) }, delim: Parenthesis, tokens: TokenStream([Token(Token { kind: Ident("feature", false), span: src/lib.rs:17:18: 17:25 (#0) }, Joint), Token(Token { kind: Comma, span: src/lib.rs:17:25: 17:26 (#0) }, Alone), Token(Token { kind: Ident("issue", false), span: src/lib.rs:17:27: 17:32 (#0) }, Alone)]) }), tokens: None }, tokens: None }), id: AttrId(102), style: Outer, span: src/lib.rs:17:1: 17:34 (#13) } }', kani-compiler/src/kani_middle/attributes.rs:154:21
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: kani_compiler::kani_middle::attributes::check_unstable_features
             at /private/tmp/kani-0.30.0/kani-compiler/src/kani_middle/attributes.rs:154:21
   3: kani_compiler::kani_middle::check_reachable_items
             at /private/tmp/kani-0.30.0/kani-compiler/src/kani_middle/mod.rs:74:13
   4: kani_compiler::codegen_cprover_gotoc::compiler_interface::GotocCodegenBackend::codegen_items
             at /private/tmp/kani-0.30.0/kani-compiler/src/codegen_cprover_gotoc/compiler_interface.rs:94:9
   5: <kani_compiler::codegen_cprover_gotoc::compiler_interface::GotocCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
             at /private/tmp/kani-0.30.0/kani-compiler/src/codegen_cprover_gotoc/compiler_interface.rs:243:25
   6: rustc_interface::passes::start_codegen
   7: <rustc_middle::ty::context::GlobalCtxt>::enter::<<rustc_interface::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core::result::Result<alloc::boxed::Box<dyn core::any::Any>, rustc_span::ErrorGuaranteed>>
   8: <rustc_interface::queries::Queries>::ongoing_codegen
   9: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
  10: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Kani unexpectedly panicked during compilation.
Please file an issue here: https://github.com/model-checking/kani/issues/new?labels=bug&template=bug_report.md

[Kani] no current codegen item.
[Kani] no current codegen location.
error: could not compile `invalid` (lib) due to 2 previous errors

------------------------------------------



failures:
    [cargo-kani] cargo-ui/unstable-attr/invalid/expected

test result: FAILED. 0 passed; 1 failed; 28 ignored; 0 measured; 0 filtered out; finished in 1.60s

Some tests failed in compiletest suite=cargo-ui mode=cargo-kani host=(none) target=(none