collapsible_span_lint_calls mangles macro invocations #15880
Description
Summary
The suggestion contains the expansion of format!
Reproducer
I tried this code:
fn foo(cx: &LateContext<'_>, expr: &Expr<'_>, lint: &'static Lint, too_generic_to_ty: Ty) {
span_lint_and_then(
cx,
lint,
expr.span,
format!("casting from `{cast_from}` to a possibly more-strictly-aligned pointer (`{cast_to}`)"),
|diag| {
diag.note(format!("the alignment of the target pointer isn't known because the alignment of `{too_generic_to_ty}` can vary"));
},
);
}I expected to see this happen:
help: collapse into
|
57 ~ span_lint_and_note(cx, lint, expr.span, format!("casting from `{cast_from}` to a possibly more-strictly-aligned pointer (`{cast_to}`)"), None, format!("the alignment of the target pointer isn't known because the alignment of `{too_generic_to_ty}` can vary"));
Instead, this happened:
help: collapse into
|
57 ~ span_lint_and_note(cx, lint, expr.span, $crate::__export::must_use({
58 + $crate::fmt::format($crate::__export::format_args!($($arg)*))
59 + }), None, $crate::__export::must_use({
60 + $crate::fmt::format($crate::__export::format_args!($($arg)*))
61 ~ }));
Version
rustc 1.92.0-nightly (839222065 2025-10-05)
binary: rustc
commit-hash: 839222065a44ac21c15df68ed2f2f3c0127b0b8e
commit-date: 2025-10-05
host: x86_64-unknown-linux-gnu
release: 1.92.0-nightly
LLVM version: 21.1.2
Additional Labels
@rustbot claim