Inline asm errors don't report file/line no information #72664
Labels
A-diagnostics
Area: Messages for errors, warnings, and lints
A-inline-assembly
Area: Inline assembly (`asm!(…)`)
C-bug
Category: This is a bug.
D-papercut
Diagnostics: An error or lint that needs small tweaks.
D-terse
Diagnostics: An error or lint that doesn't give enough information about the problem at hand.
F-asm
`#![feature(asm)]` (not `llvm_asm`)
requires-nightly
This issue requires a nightly compiler in some way.
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
Comments
jonas-schievink
added
A-diagnostics
|
This is a shame. If someone is to take this up, you will probably have to do something similar to what we do for |
estebank
added
D-papercut
|
Yes, didn't see the link. |
RalfJung
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to RalfJung/rust
that referenced
this issue
May 30, 2020
Improve inline asm error diagnostics Previously we were just using the raw LLVM error output (with line, caret, etc) as the diagnostic message, which ends up looking rather out of place with our existing diagnostics. The new diagnostics properly format the diagnostics and also take advantage of LLVM's per-line `srcloc` attribute to map an error in inline assembly directly to the relevant line of source code. Incidentally also fixes rust-lang#71639 by disabling `srcloc` metadata during LTO builds since we don't know what crate it might have come from. We can only resolve `srcloc`s from the currently crate since it indexes into the source map for the current crate. Fixes rust-lang#72664 Fixes rust-lang#71639 r? @petrochenkov ### Old style ```rust #![feature(llvm_asm)] fn main() { unsafe { let _x: i32; llvm_asm!( "mov $0, $1 invalid_instruction $0, $1 mov $0, $1" : "=&r" (_x) : "r" (0) :: "intel" ); } } ``` ``` error: <inline asm>:3:14: error: invalid instruction mnemonic 'invalid_instruction' invalid_instruction ecx, eax ^~~~~~~~~~~~~~~~~~~ --> src/main.rs:6:9 | 6 | / llvm_asm!( 7 | | "mov $0, $1 8 | | invalid_instruction $0, $1 9 | | mov $0, $1" ... | 12 | | :: "intel" 13 | | ); | |__________^ ``` ### New style ```rust #![feature(asm)] fn main() { unsafe { asm!( "mov {0}, {1} invalid_instruction {0}, {1} mov {0}, {1}", out(reg) _, in(reg) 0i64, ); } } ``` ``` error: invalid instruction mnemonic 'invalid_instruction' --> test.rs:7:14 | 7 | invalid_instruction {0}, {1} | ^ | note: instantiated into assembly here --> <inline asm>:3:14 | 3 | invalid_instruction rax, rcx | ^^^^^^^^^^^^^^^^^^^ ```
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When an error within the assembly body of an inline asm happens (such as an invalid opcode), rust reports the error without pointing which inline asm instance (e.g. which file/line) caused it to happen. For instance:
The above "wrong" inline asm (on x86 32-bit) will report the following:
This makes it hard to track down where the error is caused.
Playground link.
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rustc version: 1.45.0-nightly(2020-05-26 5239f5c)
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