bjoernager/rust
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Handle _ properly in a couple of places.

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Currently (PatKind::Wild` (i.e. `_`) gets turned by
`lower_fn_params_to_names` into an empty identifier, which means it is
printed incorrectly by HIR pretty printing.

And likewise for `lower_fn_params_to_names`, which affects some error
messages.

This commit fixes them. This requires a slight tweak in a couple of
places to continue using parameter numbers in some error messages. And
it improves the output of `tests/ui/typeck/cyclic_type_ice.rs`:
`/* _ */` is a better suggestion than `/*  */`.
This commit is contained in:
Nicholas Nethercote 2025-03-14 08:40:43 +11:00
parent 9714f60f1d
commit 958bc7b365
6 changed files with 34 additions and 14 deletions
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5
compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
View file

@ -1998,7 +1998,10 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
.iter()
.enumerate()
.map(|(i, ident)| {
if ident.name.is_empty() || ident.name == kw::SelfLower {
if ident.name.is_empty()
|| ident.name == kw::Underscore
|| ident.name == kw::SelfLower
{
format!("arg{i}")
} else {
format!("{ident}")