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Rollup merge of #115924 - compiler-errors:non-exhaustive-1-zst, r=RalfJung

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Don't complain on a single non-exhaustive 1-ZST

r? RalfJung, though you mentioned being busy, so feel free to reassign.

This doesn't actually attempt to make the diagnostic better, so when we have two non-exhaustive 1-ZSTs in a struct, we still just point to one. 🤷

Fixes #115922
This commit is contained in:
Guillaume Gomez 2023-09-19 11:35:51 +02:00 • committed by GitHub
commit f1edecfaab
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3 changed files with 110 additions and 20 deletions
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48
compiler/rustc_hir_analysis/src/check/check.rs
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@ -1201,25 +1201,35 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, adt: ty::AdtDef<'tcx>)
);
return;
}
for (span, _trivial, non_exhaustive) in field_infos {
if let Some((descr, def_id, args, non_exhaustive)) = non_exhaustive {
tcx.struct_span_lint_hir(
REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
tcx.hir().local_def_id_to_hir_id(adt.did().expect_local()),
span,
"zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types",
|lint| {
let note = if non_exhaustive {
"is marked with `#[non_exhaustive]`"
} else {
"contains private fields"
};
let field_ty = tcx.def_path_str_with_args(def_id, args);
lint
.note(format!("this {descr} contains `{field_ty}`, which {note}, \
and makes it not a breaking change to become non-zero-sized in the future."))
},
)
let mut prev_non_exhaustive_1zst = false;
for (span, _trivial, non_exhaustive_1zst) in field_infos {
if let Some((descr, def_id, args, non_exhaustive)) = non_exhaustive_1zst {
// If there are any non-trivial fields, then there can be no non-exhaustive 1-zsts.
// Otherwise, it's only an issue if there's >1 non-exhaustive 1-zst.
if non_trivial_count > 0 || prev_non_exhaustive_1zst {
tcx.struct_span_lint_hir(
REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
tcx.hir().local_def_id_to_hir_id(adt.did().expect_local()),
span,
"zero-sized fields in `repr(transparent)` cannot \
contain external non-exhaustive types",
|lint| {
let note = if non_exhaustive {
"is marked with `#[non_exhaustive]`"
} else {
"contains private fields"
};
let field_ty = tcx.def_path_str_with_args(def_id, args);
lint.note(format!(
"this {descr} contains `{field_ty}`, which {note}, \
and makes it not a breaking change to become \
non-zero-sized in the future."
))
},
)
} else {
prev_non_exhaustive_1zst = true;
}
}
}
}