Closed
Description
Code
I encountered this bug while running tests for this repo under clang-11. To do that, I ran
.../linux-kernel-module-rust/tests$ CLANG=clang-11 ./run_tests.py
On versions starting with nightly-2020-09-22, the compiler produces the three errors about if let Some(_) shown in the Error output section below. I applied the three compiler suggestions, resulting in this diff
diff --git a/src/file_operations.rs b/src/file_operations.rs
index 1f7d85c..c2ba4b8 100644
--- a/src/file_operations.rs
+++ b/src/file_operations.rs
@@ -144,17 +144,17 @@ impl<T: FileOperations> FileOperationsVtable<T> {
pub(crate) const VTABLE: bindings::file_operations = bindings::file_operations {
open: Some(open_callback::<T>),
release: Some(release_callback::<T>),
- read: if let Some(_) = T::READ {
+ read: if T::READ.is_some() = T::READ {
Some(read_callback::<T>)
} else {
None
},
- write: if let Some(_) = T::WRITE {
+ write: if T::WRITE.is_some() = T::WRITE {
Some(write_callback::<T>)
} else {
None
},
- llseek: if let Some(_) = T::SEEK {
+ llseek: if T::SEEK.is_some() = T::SEEK {
Some(llseek_callback::<T>)
} else {
Nonewhich upon re-running the tests produced the second error shown below.
The original code in part reads
...
impl<T: FileOperations> FileOperationsVtable<T> {
pub(crate) const VTABLE: bindings::file_operations = bindings::file_operations {
open: Some(open_callback::<T>),
release: Some(release_callback::<T>),
read: if T::READ.is_some() = T::READ {
Some(read_callback::<T>)
} else {
None
},
write: if T::WRITE.is_some() = T::WRITE {
Some(write_callback::<T>)
} else {
None
},
llseek: if T::SEEK.is_some() = T::SEEK {
Some(llseek_callback::<T>)
} else {
None
},
...I realize that this isn't a minimal example, but I'm not sure what could be causing this bug, so I don't know how to minimize it.
Meta
I'm using nightly because the repo I'm working in requires it.
I tested several different versions to try to isolate when the bug appeared. The earliest example I could find was:
rustc --version --verbose:
rustc 1.48.0-nightly (0e2c1281e 2020-09-07)
binary: rustc
commit-hash: 0e2c1281e909ca38479b97962fc9248f75d66412
commit-date: 2020-09-07
host: x86_64-unknown-linux-gnu
release: 1.48.0-nightly
LLVM version: 11.0
However, the unmodified code above only generates normal ("external") compiler errors in versions starting with nightly-2020-09-22, as far as I can tell. A different message also appears in versions before nightly-2020-09-08.
Error output
The first error message suggests a fix:
error: redundant pattern matching, consider using `is_some()`
--> /home/<user>/<project>/linux-kernel-module-rust/src/file_operations.rs:147:22
|
147 | read: if let Some(_) = T::READ {
| -------^^^^^^^---------- help: try this: `if T::READ.is_some()`
|
= note: `-D clippy::redundant-pattern-matching` implied by `-D warnings`
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pattern_matching
error: redundant pattern matching, consider using `is_some()`
--> /home/<user>/<project>/linux-kernel-module-rust/src/file_operations.rs:152:23
|
152 | write: if let Some(_) = T::WRITE {
| -------^^^^^^^----------- help: try this: `if T::WRITE.is_some()`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pattern_matching
error: redundant pattern matching, consider using `is_some()`
--> /home/<user>/<project>/linux-kernel-module-rust/src/file_operations.rs:157:24
|
157 | llseek: if let Some(_) = T::SEEK {
| -------^^^^^^^---------- help: try this: `if T::SEEK.is_some()`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pattern_matching
error: aborting due to 3 previous errors
error: could not compile `linux-kernel-module`
but when I apply that fix, I get:
error: internal compiler error: compiler/rustc_typeck/src/check/mod.rs:3394:25: while adjusting Expr { hir_id: HirId { owner: DefId(0:141 ~ linux_kernel_module[2b6b]::file_operations[0]::{{impl}}[1]::VTAB
LE[0]), local_id: 42 }, kind: Path(TypeRelative(Ty { hir_id: HirId { owner: DefId(0:141 ~ linux_kernel_module[2b6b]::file_operations[0]::{{impl}}[1]::VTABLE[0]), local_id: 40 }, kind: Path(Resolved(None,
Path { span: /home/<user>/<project>/linux-kernel-module-rust/src/file_operations.rs:147:18: 147:25 (#0), res: Def(TyParam, DefId(0:140 ~ linux_kernel_module[2b6b]::file_operations[0]::{{impl}}[1]::T[0])), s
egments: [PathSegment { ident: T#0, hir_id: Some(HirId { owner: DefId(0:141 ~ linux_kernel_module[2b6b]::file_operations[0]::{{impl}}[1]::VTABLE[0]), local_id: 39 }), res: Some(Def(TyParam, DefId(0:140 ~
linux_kernel_module[2b6b]::file_operations[0]::{{impl}}[1]::T[0]))), args: None, infer_args: true }] })), span: /home/<user>/<project>/linux-kernel-module-rust/src/file_operations.rs:147:18: 147:25 (#0) },
PathSegment { ident: READ#0, hir_id: Some(HirId { owner: DefId(0:141 ~ linux_kernel_module[2b6b]::file_operations[0]::{{impl}}[1]::VTABLE[0]), local_id: 41 }), res: Some(Err), args: None, infer_args: true
})), attrs: ThinVec(None), span: /home/<user>/<project>/linux-kernel-module-rust/src/file_operations.rs:147:18: 147:25 (#0) }, can't compose [Borrow(Ref('_#0r, Not)) -> &Option<for<'r, 's, 't0> fn(&'r T, &
's File, &'t0 mut UserSlicePtrWriter, u64) -> core::result::Result<(), error::Error>>] and [Borrow(Ref('_#2r, Not)) -> &Option<for<'r, 's, 't0> fn(&'r T, &'s File, &'t0 mut UserSlicePtrWriter, u64) -> cor
e::result::Result<(), error::Error>>]
thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:945:9
Note that I have redacted my local username and project name.
Backtrace
stack backtrace: [39/1895]
0: std::panicking::begin_panic
1: rustc_errors::HandlerInner::bug
2: rustc_errors::Handler::bug
3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
4: rustc_middle::ty::context::tls::with_opt::{{closure}}
5: rustc_middle::ty::context::tls::with_opt
6: rustc_middle::util::bug::opt_span_bug_fmt
7: rustc_middle::util::bug::bug_fmt
8: rustc_typeck::check::FnCtxt::apply_adjustments
9: rustc_typeck::check::method::confirm::ConfirmContext::confirm
10: rustc_typeck::check::method::<impl rustc_typeck::check::FnCtxt>::lookup_method
11: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
12: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation
13: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
14: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation
15: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
16: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation
17: rustc_typeck::check::_match::<impl rustc_typeck::check::FnCtxt>::check_match
18: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
19: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation
20: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_coercable_to_type
21: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
22: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation
23: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_coercable_to_type
24: rustc_infer::infer::InferCtxtBuilder::enter
25: rustc_typeck::check::typeck
26: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck>::compute
27: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
28: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
29: rustc_middle::ty::query::plumbing::<impl rustc_query_system::query::QueryContext for rustc_middle::ty::context::TyCtxt>::start_query::{{closure}}::{{closure}}::{{closure}}
30: rustc_query_system::query::plumbing::get_query_impl
31: rustc_query_system::query::plumbing::ensure_query_impl
32: rustc_typeck::check::typeck_item_bodies
33: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck_item_bodies>::compute
34: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
35: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
36: rustc_data_structures::stack::ensure_sufficient_stack
37: rustc_query_system::query::plumbing::get_query_impl
38: rustc_typeck::check_crate
39: rustc_interface::passes::analysis
40: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
41: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
42: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
43: rustc_data_structures::stack::ensure_sufficient_stack
44: rustc_query_system::query::plumbing::get_query_impl
45: rustc_interface::passes::QueryContext::enter
46: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
47: rustc_span::with_source_map
48: rustc_interface::interface::create_compiler_and_run
49: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
...
query stack during panic:
#0 [typeck] type-checking `file_operations::FileOperationsVtable::<T>::VTABLE`
#1 [typeck_item_bodies] type-checking all item bodies
#2 [analysis] running analysis passes on this crate
end of query stack