panic location counts tabs as four columns instead of one

[edwloef]

I tried this code (note that indentation is in tabs, not spaces):

fn main() {
	panic!();
}

I expected to see this happen:

thread 'main' panicked at src/main.rs:2:2:
explicit panic

Instead, this happened:

thread 'main' panicked at src/main.rs:2:5:
explicit panic

Meta

rustc --version --verbose:

rustc 1.90.0 (1159e78c4 2025-09-14)
binary: rustc
commit-hash: 1159e78c4747b02ef996e55082b704c09b970588
commit-date: 2025-09-14
host: x86_64-unknown-linux-gnu
release: 1.90.0
LLVM version: 20.1.8

Backtrace

<backtrace>

[Qelxiros]

This seems to be expected behavior: https://doc.rust-lang.org/stable/std/macro.panic.html says that it prints file/line/column information.

[edwloef]

If this is indeed intended behavior, it would be nice to have documented that tabs either count for 4 columns, or an explicitly unspecified number of columns.

[Andriamanitra]

This behavior is

• not correct even if you think it should be reporting the visual column, because it doesn't handle tab stops properly. If you use mixed indentation like " \t" the visual column doesn't change but the reported column does, as it seems to count a tab as 4 spaces always. Tab stops also depend on the environment, as they may be configured in the terminal using tabs(1p).
• not consistent with rustc which reports offsets for compile time errors in code points (\t counts as 1).
• not consistent with errors from any of the other programming language tooling that I tested:
  • clang uses bytes
  • go uses bytes
  • ruff uses code points (or similar)
  • gcc uses 8 columns per \t
  • ghc uses 8 columns per \t