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Rollup merge of #129829 - compiler-errors:decode-non-optional, r=lcnr

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Make decoding non-optional `LazyArray` panic if not set

Tables may be [defined](9649706ead/compiler/rustc_metadata/src/rmeta/mod.rs (L377)) as `optional:` or `defaulted:`. If optional, if we try to read a value from a key that was never encoded, we should panic. This has high value in ensuring correctness over a defaulted table, so the tradeoff is worth considering, since it signals the compiler has a buggy encode impl, rather than just defaulting to a value.

HOWEVER, `optional:` arrays were side-stepping this. So this PR fixes that, and makes `optional:` tables of `LazyArray` act like `LazyValue`, and panic if it's not assigned a value during encoding.

During this PR, I found that `deduced_param_attrs` has buggy (?? i think??) implementation where it will refuse to encode cross-crate `deduced_param_attrs` unless we're codegening, we're optimizing the library, and incremental is disabled. This seems incredibly wrong, but I don't want to fix it in this PR.
9649706ead/compiler/rustc_metadata/src/rmeta/encoder.rs (L1733-L1747)
This commit is contained in:
Matthias Krüger 2024-09-02 22:35:19 +02:00 committed by GitHub
commit c6410f5066
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1 changed files with 18 additions and 5 deletions
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23
compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
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@ -71,8 +71,8 @@ impl<'a, 'tcx, T: Copy + Decodable<DecodeContext<'a, 'tcx>>> ProcessQueryValue<'
for Option<DecodeIterator<'a, 'tcx, T>>
{
#[inline(always)]
fn process_decoded(self, tcx: TyCtxt<'tcx>, _err: impl Fn() -> !) -> &'tcx [T] {
if let Some(iter) = self { tcx.arena.alloc_from_iter(iter) } else { &[] }
fn process_decoded(self, tcx: TyCtxt<'tcx>, err: impl Fn() -> !) -> &'tcx [T] {
if let Some(iter) = self { tcx.arena.alloc_from_iter(iter) } else { err() }
}
}
@ -84,12 +84,12 @@ impl<'a, 'tcx, T: Copy + Decodable<DecodeContext<'a, 'tcx>>>
fn process_decoded(
self,
tcx: TyCtxt<'tcx>,
_err: impl Fn() -> !,
err: impl Fn() -> !,
) -> ty::EarlyBinder<'tcx, &'tcx [T]> {
ty::EarlyBinder::bind(if let Some(iter) = self {
tcx.arena.alloc_from_iter(iter)
} else {
&[]
err()
})
}
}
@ -300,7 +300,20 @@ provide! { tcx, def_id, other, cdata,
.unwrap_or_else(|| panic!("{def_id:?} does not have eval_static_initializer")))
}
trait_def => { table }
deduced_param_attrs => { table }
deduced_param_attrs => {
// FIXME: `deduced_param_attrs` has some sketchy encoding settings,
// where we don't encode unless we're optimizing, doing codegen,
// and not incremental (see `encoder.rs`). I don't think this is right!
cdata
.root
.tables
.deduced_param_attrs
.get(cdata, def_id.index)
.map(|lazy| {
&*tcx.arena.alloc_from_iter(lazy.decode((cdata, tcx)))
})
.unwrap_or_default()
}
is_type_alias_impl_trait => {
debug_assert_eq!(tcx.def_kind(def_id), DefKind::OpaqueTy);
cdata.root.tables.is_type_alias_impl_trait.get(cdata, def_id.index)