mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-23 15:23:46 +00:00
warn about uninit multi-variant enums
This commit is contained in:
Ralf Jung
parent
c2dbebd3d4
commit
87b49764bc
@ -1922,6 +1922,14 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
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None
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}
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/// Test if this enum has several actually "existing" variants.
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/// Zero-sized uninhabited variants do not always have a tag assigned and thus do not "exist".
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fn is_multi_variant(adt: &ty::AdtDef) -> bool {
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// As an approximation, we only count dataless variants. Those are definitely inhabited.
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let existing_variants = adt.variants.iter().filter(|v| v.fields.is_empty()).count();
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existing_variants > 1
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}
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/// Return `Some` only if we are sure this type does *not*
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/// allow zero initialization.
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fn ty_find_init_error<'tcx>(
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@ -1950,7 +1958,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
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}
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// Recurse and checks for some compound types.
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Adt(adt_def, substs) if !adt_def.is_union() => {
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// First check f this ADT has a layout attribute (like `NonNull` and friends).
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// First check if this ADT has a layout attribute (like `NonNull` and friends).
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use std::ops::Bound;
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match tcx.layout_scalar_valid_range(adt_def.did) {
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// We exploit here that `layout_scalar_valid_range` will never
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@ -2001,10 +2009,20 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
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)
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})
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}
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// Multi-variant enums are tricky: if all but one variant are
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// uninhabited, we might actually do layout like for a single-variant
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// enum, and then even leaving them uninitialized could be okay.
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_ => None, // Conservative fallback for multi-variant enum.
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// Multi-variant enum.
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_ => {
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if init == InitKind::Uninit && is_multi_variant(adt_def) {
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let span = tcx.def_span(adt_def.did);
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Some((
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"enums have to be initialized to a variant".to_string(),
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Some(span),
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))
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} else {
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// In principle, for zero-initialization we could figure out which variant corresponds
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// to tag 0, and check that... but for now we just accept all zero-initializations.
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None
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}
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}
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}
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}
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Tuple(..) => {
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@ -23,6 +23,18 @@ enum WrapEnum<T> { Wrapped(T) }
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#[repr(transparent)]
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pub(crate) struct NonBig(u64);
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/// A two-variant enum, thus needs a tag and may not remain uninitialized.
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enum Fruit {
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Apple,
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Banana,
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}
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/// Looks like two variants but really only has one.
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enum OneFruit {
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Apple(!),
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Banana,
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}
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#[allow(unused)]
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fn generic<T: 'static>() {
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unsafe {
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@ -80,6 +92,9 @@ fn main() {
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let _val: NonBig = mem::zeroed();
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let _val: NonBig = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
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let _val: Fruit = mem::zeroed();
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let _val: Fruit = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
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// Transmute-from-0
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let _val: &'static i32 = mem::transmute(0usize); //~ ERROR: does not permit zero-initialization
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let _val: &'static [i32] = mem::transmute((0usize, 0usize)); //~ ERROR: does not permit zero-initialization
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@ -96,5 +111,9 @@ fn main() {
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let _val: MaybeUninit<&'static i32> = mem::zeroed();
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let _val: i32 = mem::zeroed();
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let _val: bool = MaybeUninit::zeroed().assume_init();
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// Some things that happen to work due to rustc implementation details,
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// but are not guaranteed to keep working.
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let _val: i32 = mem::uninitialized();
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let _val: OneFruit = mem::uninitialized();
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}
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}
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@ -1,5 +1,5 @@
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error: the type `&T` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:29:32
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--> $DIR/uninitialized-zeroed.rs:41:32
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LL | let _val: &'static T = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -15,7 +15,7 @@ LL | #![deny(invalid_value)]
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= note: references must be non-null
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error: the type `&T` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:30:32
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--> $DIR/uninitialized-zeroed.rs:42:32
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LL | let _val: &'static T = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -26,7 +26,7 @@ LL | let _val: &'static T = mem::uninitialized();
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= note: references must be non-null
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error: the type `Wrap<&T>` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:32:38
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--> $DIR/uninitialized-zeroed.rs:44:38
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LL | let _val: Wrap<&'static T> = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -41,7 +41,7 @@ LL | struct Wrap<T> { wrapped: T }
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| ^^^^^^^^^^
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error: the type `Wrap<&T>` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:33:38
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--> $DIR/uninitialized-zeroed.rs:45:38
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LL | let _val: Wrap<&'static T> = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -56,7 +56,7 @@ LL | struct Wrap<T> { wrapped: T }
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| ^^^^^^^^^^
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error: the type `!` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:40:23
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--> $DIR/uninitialized-zeroed.rs:52:23
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LL | let _val: ! = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -67,7 +67,7 @@ LL | let _val: ! = mem::zeroed();
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= note: the `!` type has no valid value
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error: the type `!` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:41:23
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--> $DIR/uninitialized-zeroed.rs:53:23
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LL | let _val: ! = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -78,7 +78,7 @@ LL | let _val: ! = mem::uninitialized();
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= note: the `!` type has no valid value
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error: the type `(i32, !)` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:43:30
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--> $DIR/uninitialized-zeroed.rs:55:30
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LL | let _val: (i32, !) = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -89,7 +89,7 @@ LL | let _val: (i32, !) = mem::zeroed();
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= note: the `!` type has no valid value
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error: the type `(i32, !)` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:44:30
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--> $DIR/uninitialized-zeroed.rs:56:30
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LL | let _val: (i32, !) = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -100,7 +100,7 @@ LL | let _val: (i32, !) = mem::uninitialized();
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= note: the `!` type has no valid value
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error: the type `Void` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:46:26
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--> $DIR/uninitialized-zeroed.rs:58:26
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LL | let _val: Void = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -111,7 +111,7 @@ LL | let _val: Void = mem::zeroed();
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= note: enums with no variants have no valid value
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error: the type `Void` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:47:26
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--> $DIR/uninitialized-zeroed.rs:59:26
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LL | let _val: Void = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -122,7 +122,7 @@ LL | let _val: Void = mem::uninitialized();
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= note: enums with no variants have no valid value
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error: the type `&i32` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:49:34
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--> $DIR/uninitialized-zeroed.rs:61:34
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LL | let _val: &'static i32 = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -133,7 +133,7 @@ LL | let _val: &'static i32 = mem::zeroed();
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= note: references must be non-null
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error: the type `&i32` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:50:34
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--> $DIR/uninitialized-zeroed.rs:62:34
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LL | let _val: &'static i32 = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -144,7 +144,7 @@ LL | let _val: &'static i32 = mem::uninitialized();
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= note: references must be non-null
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error: the type `Ref` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:52:25
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--> $DIR/uninitialized-zeroed.rs:64:25
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LL | let _val: Ref = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -159,7 +159,7 @@ LL | struct Ref(&'static i32);
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| ^^^^^^^^^^^^
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error: the type `Ref` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:53:25
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--> $DIR/uninitialized-zeroed.rs:65:25
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LL | let _val: Ref = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -174,7 +174,7 @@ LL | struct Ref(&'static i32);
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| ^^^^^^^^^^^^
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error: the type `fn()` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:55:26
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--> $DIR/uninitialized-zeroed.rs:67:26
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LL | let _val: fn() = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -185,7 +185,7 @@ LL | let _val: fn() = mem::zeroed();
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= note: function pointers must be non-null
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error: the type `fn()` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:56:26
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--> $DIR/uninitialized-zeroed.rs:68:26
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LL | let _val: fn() = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -196,7 +196,7 @@ LL | let _val: fn() = mem::uninitialized();
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= note: function pointers must be non-null
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error: the type `Wrap<fn()>` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:58:32
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--> $DIR/uninitialized-zeroed.rs:70:32
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LL | let _val: Wrap<fn()> = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -211,7 +211,7 @@ LL | struct Wrap<T> { wrapped: T }
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| ^^^^^^^^^^
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error: the type `Wrap<fn()>` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:59:32
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--> $DIR/uninitialized-zeroed.rs:71:32
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|
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LL | let _val: Wrap<fn()> = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -226,7 +226,7 @@ LL | struct Wrap<T> { wrapped: T }
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| ^^^^^^^^^^
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error: the type `WrapEnum<fn()>` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:61:36
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--> $DIR/uninitialized-zeroed.rs:73:36
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|
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LL | let _val: WrapEnum<fn()> = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -241,7 +241,7 @@ LL | enum WrapEnum<T> { Wrapped(T) }
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| ^
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error: the type `WrapEnum<fn()>` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:62:36
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--> $DIR/uninitialized-zeroed.rs:74:36
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|
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LL | let _val: WrapEnum<fn()> = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -256,7 +256,7 @@ LL | enum WrapEnum<T> { Wrapped(T) }
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| ^
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error: the type `Wrap<(RefPair, i32)>` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:64:42
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--> $DIR/uninitialized-zeroed.rs:76:42
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|
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LL | let _val: Wrap<(RefPair, i32)> = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -271,7 +271,7 @@ LL | struct RefPair((&'static i32, i32));
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| ^^^^^^^^^^^^^^^^^^^
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error: the type `Wrap<(RefPair, i32)>` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:65:42
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--> $DIR/uninitialized-zeroed.rs:77:42
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|
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LL | let _val: Wrap<(RefPair, i32)> = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -286,7 +286,7 @@ LL | struct RefPair((&'static i32, i32));
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| ^^^^^^^^^^^^^^^^^^^
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error: the type `std::ptr::NonNull<i32>` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:67:34
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--> $DIR/uninitialized-zeroed.rs:79:34
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|
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LL | let _val: NonNull<i32> = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -297,7 +297,7 @@ LL | let _val: NonNull<i32> = mem::zeroed();
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= note: `std::ptr::NonNull<i32>` must be non-null
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error: the type `std::ptr::NonNull<i32>` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:68:34
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--> $DIR/uninitialized-zeroed.rs:80:34
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|
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LL | let _val: NonNull<i32> = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -308,7 +308,7 @@ LL | let _val: NonNull<i32> = mem::uninitialized();
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= note: `std::ptr::NonNull<i32>` must be non-null
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error: the type `*const dyn std::marker::Send` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:70:37
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--> $DIR/uninitialized-zeroed.rs:82:37
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|
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LL | let _val: *const dyn Send = mem::zeroed();
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| ^^^^^^^^^^^^^
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@ -319,7 +319,7 @@ LL | let _val: *const dyn Send = mem::zeroed();
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= note: the vtable of a wide raw pointer must be non-null
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error: the type `*const dyn std::marker::Send` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:71:37
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--> $DIR/uninitialized-zeroed.rs:83:37
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|
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LL | let _val: *const dyn Send = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -330,7 +330,7 @@ LL | let _val: *const dyn Send = mem::uninitialized();
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= note: the vtable of a wide raw pointer must be non-null
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error: the type `bool` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:75:26
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--> $DIR/uninitialized-zeroed.rs:87:26
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|
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LL | let _val: bool = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -341,7 +341,7 @@ LL | let _val: bool = mem::uninitialized();
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= note: booleans must be either `true` or `false`
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error: the type `Wrap<char>` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:78:32
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--> $DIR/uninitialized-zeroed.rs:90:32
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|
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LL | let _val: Wrap<char> = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -356,7 +356,7 @@ LL | struct Wrap<T> { wrapped: T }
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| ^^^^^^^^^^
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error: the type `NonBig` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:81:28
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--> $DIR/uninitialized-zeroed.rs:93:28
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|
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LL | let _val: NonBig = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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@ -366,8 +366,26 @@ LL | let _val: NonBig = mem::uninitialized();
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|
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= note: `NonBig` must be initialized inside its custom valid range
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error: the type `Fruit` does not permit being left uninitialized
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--> $DIR/uninitialized-zeroed.rs:96:27
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|
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LL | let _val: Fruit = mem::uninitialized();
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| ^^^^^^^^^^^^^^^^^^^^
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| |
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| this code causes undefined behavior when executed
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| help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
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|
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note: enums have to be initialized to a variant
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--> $DIR/uninitialized-zeroed.rs:27:1
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|
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LL | / enum Fruit {
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LL | | Apple,
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LL | | Banana,
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LL | | }
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| |_^
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error: the type `&i32` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:84:34
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--> $DIR/uninitialized-zeroed.rs:99:34
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|
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LL | let _val: &'static i32 = mem::transmute(0usize);
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| ^^^^^^^^^^^^^^^^^^^^^^
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@ -378,7 +396,7 @@ LL | let _val: &'static i32 = mem::transmute(0usize);
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= note: references must be non-null
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error: the type `&[i32]` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:85:36
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--> $DIR/uninitialized-zeroed.rs:100:36
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|
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LL | let _val: &'static [i32] = mem::transmute((0usize, 0usize));
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -389,7 +407,7 @@ LL | let _val: &'static [i32] = mem::transmute((0usize, 0usize));
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= note: references must be non-null
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error: the type `std::num::NonZeroU32` does not permit zero-initialization
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--> $DIR/uninitialized-zeroed.rs:86:32
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--> $DIR/uninitialized-zeroed.rs:101:32
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|
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LL | let _val: NonZeroU32 = mem::transmute(0);
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| ^^^^^^^^^^^^^^^^^
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@ -400,7 +418,7 @@ LL | let _val: NonZeroU32 = mem::transmute(0);
|
||||
= note: `std::num::NonZeroU32` must be non-null
|
||||
|
||||
error: the type `std::ptr::NonNull<i32>` does not permit zero-initialization
|
||||
--> $DIR/uninitialized-zeroed.rs:89:34
|
||||
--> $DIR/uninitialized-zeroed.rs:104:34
|
||||
|
|
||||
LL | let _val: NonNull<i32> = MaybeUninit::zeroed().assume_init();
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
@ -411,7 +429,7 @@ LL | let _val: NonNull<i32> = MaybeUninit::zeroed().assume_init();
|
||||
= note: `std::ptr::NonNull<i32>` must be non-null
|
||||
|
||||
error: the type `std::ptr::NonNull<i32>` does not permit being left uninitialized
|
||||
--> $DIR/uninitialized-zeroed.rs:90:34
|
||||
--> $DIR/uninitialized-zeroed.rs:105:34
|
||||
|
|
||||
LL | let _val: NonNull<i32> = MaybeUninit::uninit().assume_init();
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
@ -422,7 +440,7 @@ LL | let _val: NonNull<i32> = MaybeUninit::uninit().assume_init();
|
||||
= note: `std::ptr::NonNull<i32>` must be non-null
|
||||
|
||||
error: the type `bool` does not permit being left uninitialized
|
||||
--> $DIR/uninitialized-zeroed.rs:91:26
|
||||
--> $DIR/uninitialized-zeroed.rs:106:26
|
||||
|
|
||||
LL | let _val: bool = MaybeUninit::uninit().assume_init();
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
@ -432,5 +450,5 @@ LL | let _val: bool = MaybeUninit::uninit().assume_init();
|
||||
|
|
||||
= note: booleans must be either `true` or `false`
|
||||
|
||||
error: aborting due to 35 previous errors
|
||||
error: aborting due to 36 previous errors
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user