clippy's lint cast_lossless replaces macro invocation with macro definition. #11458
Description
Summary
Clippy failed with this output. I had cut out the irrelevant parts, since the output was very long (1522 lines). I can still provide it if necessary
Checking rustc_codegen_clr v0.1.0 (/home/michal/Rust/rustc_codegen_clr)
warning: failed to automatically apply fixes suggested by rustc to crate `rustc_codegen_clr`
after fixes were automatically applied the compiler reported errors within these files:
* src/codegen/place.rs
* src/statement.rs
This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag
The following errors were reported:
error: expected type, found `$`
--> src/statement.rs:78:57
|
78 | Type::I8 => vec![BaseIR::LDConstI32(i32::from((<$dest>::from_ne_bytes(($var as $src).to_ne_bytes()))))],
| ^ expected type
error: expected type, found `$`
--> src/statement.rs:80:58
|
80 | Type::I16 => vec![BaseIR::LDConstI32(i32::from((<$dest>::from_ne_bytes(($var as $src).to_ne_bytes()))))],
| ^ expected type
This seems to be the lint causing the issue:
warning: casting `i8` to `i32` may become silently lossy if you later change the type
--> src/statement.rs:78:45
|
78 | Type::I8 => vec![BaseIR::LDConstI32(sign_cast!(scalar_u128, u8, i8) as i32)],
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `i32::from((<$dest>::from_ne_bytes(($var as $src).to_ne_bytes())))`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#cast_lossless
It seems like it does not respect boundaries of macros, replacing macro invocation with macro definition.
Reproducer
This is the relevant macro:
macro_rules! sign_cast {
($var:ident,$src:ty,$dest:ty) => {
(<$dest>::from_ne_bytes(($var as $src).to_ne_bytes()))
};
}It is used here:
let scalar_u128 = match scalar {
Scalar::Int(scalar_int) => scalar_int
.try_to_uint(scalar.size())
.expect("IMPOSSIBLE. Size of scalar was not equal to itself."),
Scalar::Ptr(_, _) => todo!("Can't handle scalar pointers yet!"),
};
match scalar_type {
Type::I8 => vec![BaseIR::LDConstI32(sign_cast!(scalar_u128, u8, i8) as i32)],
Type::U8 => vec![BaseIR::LDConstI32(scalar_u128 as u8 as i32)],
Type::I16 => vec![BaseIR::LDConstI32(sign_cast!(scalar_u128, u16, i16) as i32)],
Type::U16 => vec![BaseIR::LDConstI32(scalar_u128 as i32)],
Type::I32 => vec![BaseIR::LDConstI32(sign_cast!(scalar_u128, u32, i32))],
Type::U32 => vec![BaseIR::LDConstI32(scalar_u128 as i32)],
Type::F32 => vec![BaseIR::LDConstF32(f32::from_bits(scalar_u128 as u32))],
Type::Bool => vec![BaseIR::LDConstI32((scalar_u128 != 0) as u8 as i32)],
Type::I64 => vec![BaseIR::LDConstI64(sign_cast!(scalar_u128, u64, i64))],
Type::U64 => vec![BaseIR::LDConstI64(scalar_u128 as i64)],
Type::USize => vec![BaseIR::LDConstI64(scalar_u128 as i64)],
Type::ISize => vec![BaseIR::LDConstI64(scalar_u128 as i64)],
//Type::Enum(_) => vec![BaseIR::LDConstI32((scalar_u128 != 0) as u8 as i32)],
_ => todo!("can't yet handle a scalar of type {scalar_type:?}!"),
}This is a part of my larger project. I had tagged the particular version of the source code that clippy had issues with.
Version
rustc 1.74.0-nightly (9f5fc1bd4 2023-09-02)
binary: rustc
commit-hash: 9f5fc1bd443f59583e7af0d94d289f95fe1e20c4
commit-date: 2023-09-02
host: x86_64-unknown-linux-gnu
release: 1.74.0-nightly
LLVM version: 17.0.0
Additional Labels
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