ICE (failed to get layout for [type error]) when attempting to doc-test an internal struct of rustfmt

[anforowicz]

Code

To repro, try the following steps:

1. Get a local copy of https://github.com/rust-lang/rustfmt.git
2. Apply the patch from https://github.com/anforowicz/rustfmt/tree/doc-test-ice-repro (see the git diff output below)
3. Run cargo test against rustfmt

I haven't yet tried minimizing this example, because it seems that part of the repro may require depending on the internal rustc_foo crates (like rustfmt does AFAIU). At least the following does not repro the problem:

$ cat src/lib.rs
struct SomeStruct(i32);

impl SomeStruct {
    /// ```
    /// use ice_20221013::SomeStruct;
    /// SomeStruct::foo();
    /// ```
    fn foo() {
    }
}

$ cargo test
...
error[E0603]: struct `SomeStruct` is private
...

Meta

rustc --version --verbose:

rustc 1.64.0-nightly (affe0d3a0 2022-08-05)
binary: rustc
commit-hash: affe0d3a00e92fa7885e3f5d2c5073fde432d154
commit-date: 2022-08-05
host: x86_64-unknown-linux-gnu
release: 1.64.0-nightly
LLVM version: 14.0.6

I've tried to see if the ICE also repros on a more recent nightly, but with rustc 1.66.0-nightly (c0983a9aa 2022-10-12) I've hit much earlier, different errors when running cargo test against rustfmt.

Error output

$ cd ~/src/github/rustfmt
$ git diff fork/master
diff --git a/src/comment.rs b/src/comment.rs
index 4d565afc..32e1e57b 100644
--- a/src/comment.rs
+++ b/src/comment.rs
@@ -417,6 +417,12 @@ impl CodeBlockAttribute {
     /// Parse comma separated attributes list. Return rust only if all
     /// attributes are valid rust attributes
     /// See <https://doc.rust-lang.org/rustdoc/print.html#attributes>
+    ///
+    /// Example:
+    /// ```
+    /// use rustfmt::comment::CodeBlockAttribute;
+    /// let _ = CodeBlockAttribute::new("rust");
+    /// ```
     fn new(attributes: &str) -> CodeBlockAttribute {
         for attribute in attributes.split(',') {
             match attribute.trim() {

$ RUST_BACKTRACE=1 cargo test
...

   Doc-tests rustfmt-nightly

running 3 tests
test src/comment.rs - comment::CodeBlockAttribute::new (line 422) ... FAILED
test src/utils.rs - utils::trim_left_preserve_layout (line 560) - compile fail ... ok
test src/utils.rs - utils::trim_left_preserve_layout (line 546) - compile fail ... ok

failures:

---- src/comment.rs - comment::CodeBlockAttribute::new (line 422) stdout ----
error: internal compiler error: compiler/rustc_codegen_llvm/src/context.rs:974:13: failed to get layout for `[type error]`: the type `[type error]` has an unknown layout
 --> src/comment.rs:422:38
  |
2 | fn main() { #[allow(non_snake_case)] fn _doctest_main_src_comment_rs_422_0() {
  |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/affe0d3a00e92fa7885e3f5d2c5073fde432d154/compiler/rustc_errors/src/lib.rs:1332:9
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: std::panic::panic_any::<rustc_errors::ExplicitBug>
   2: <rustc_errors::HandlerInner>::span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
   3: <rustc_errors::Handler>::span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
   4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, ()>::{closure#0}, ()>
   5: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>
   6: rustc_middle::util::bug::span_bug_fmt::<rustc_span::span_encoding::Span>
   7: <rustc_codegen_llvm::context::CodegenCx as rustc_middle::ty::layout::LayoutOfHelpers>::handle_layout_err
   8: <rustc_codegen_llvm::context::CodegenCx as rustc_middle::ty::layout::LayoutOf>::spanned_layout_of::{closure#0}
   9: <core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::LocalDecl>, rustc_codegen_ssa::mir::analyze::non_ssa_locals<rustc_codegen_llvm::builder::Builder>::{closure#0}> as core::iter::traits::iterator::Iterator>::fold::<(), core::iter::traits::iterator::Iterator::for_each::call<rustc_codegen_ssa::mir::analyze::LocalKind, <alloc::vec::Vec<rustc_codegen_ssa::mir::analyze::LocalKind> as alloc::vec::spec_extend::SpecExtend<rustc_codegen_ssa::mir::analyze::LocalKind, core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::LocalDecl>, rustc_codegen_ssa::mir::analyze::non_ssa_locals<rustc_codegen_llvm::builder::Builder>::{closure#0}>>>::spec_extend::{closure#0}>::{closure#0}>
  10: rustc_codegen_ssa::mir::analyze::non_ssa_locals::<rustc_codegen_llvm::builder::Builder>
  11: rustc_codegen_ssa::mir::codegen_mir::<rustc_codegen_llvm::builder::Builder>
  12: rustc_codegen_llvm::base::compile_codegen_unit::module_codegen
  13: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, rustc_span::symbol::Symbol, rustc_codegen_ssa::ModuleCodegen<rustc_codegen_llvm::ModuleLlvm>>
  14: rustc_codegen_llvm::base::compile_codegen_unit
  15: rustc_codegen_ssa::base::codegen_crate::<rustc_codegen_llvm::LlvmCodegenBackend>
  16: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  17: <rustc_session::session::Session>::time::<alloc::boxed::Box<dyn core::any::Any>, rustc_interface::passes::start_codegen::{closure#0}>
  18: <rustc_interface::passes::QueryContext>::enter::<<rustc_interface::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core::result::Result<alloc::boxed::Box<dyn core::any::Any>, rustc_errors::ErrorGuaranteed>>
  19: <rustc_interface::queries::Queries>::ongoing_codegen
  20: <rustc_interface::interface::Compiler>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorGuaranteed>>
  21: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#1}>
  22: rustc_interface::interface::create_compiler_and_run::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>
  23: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.64.0-nightly (affe0d3a0 2022-08-05) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C codegen-units=1 -C embed-bitcode=no

query stack during panic:
end of query stack
error: aborting due to previous error

Couldn't compile the test.

failures:
    src/comment.rs - comment::CodeBlockAttribute::new (line 422)

test result: FAILED. 2 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.05s

error: test failed, to rerun pass '--doc'

[anforowicz]

Ooops... I see that this is probably a duplicate of issue #102366