v32.1.1-rc3

CHANGELOG.md

@@ -1,3 +1,6 @@
+# 36.1.1-rc3 (api=2.0.0, abi=2.0.0)
+- Allow structures to compute their single-niche evaluation properly.
+
 # 36.1.1-rc2 (api=2.0.0, abi=2.0.0)
 - Add the `#[stabby::vt_attr(_)]` sub-attribute to `#[stabby::stabby]` on traits, letting you place custom attributes on the v-tables generated for a trait.
 - Add support for `core::ffi::c_void`.

Cargo.toml

@@ -33,12 +33,12 @@ license = " EPL-2.0 OR Apache-2.0"
 categories = ["development-tools::ffi", "no-std::no-alloc"]
 repository = "https://github.com/ZettaScaleLabs/stabby"
 readme = "stabby/README.md"
-version = "36.1.1-rc2"                                           # Track
+version = "36.1.1-rc3"                                           # Track
 
 [workspace.dependencies]
-stabby-macros = { path = "./stabby-macros/", version = "36.1.1-rc2", default-features = false } # Track
-stabby-abi = { path = "./stabby-abi/", version = "36.1.1-rc2", default-features = false }       # Track
-stabby = { path = "./stabby/", version = "36.1.1-rc2", default-features = false }               # Track
+stabby-macros = { path = "./stabby-macros/", version = "36.1.1-rc3", default-features = false } # Track
+stabby-abi = { path = "./stabby-abi/", version = "36.1.1-rc3", default-features = false }       # Track
+stabby = { path = "./stabby/", version = "36.1.1-rc3", default-features = false }               # Track
 
 abi_stable = "0.11.0"
 libc = "0.2"

stabby-abi/src/istable.rs

@@ -385,9 +385,13 @@ unsafe impl<A: IStable, B: IStable> IStable for FieldPair<A, B> {
         <A::UnusedBits as IBitMask>::BitOr<<AlignedAfter<B, A::Size> as IStable>::UnusedBits>;
     type Size = <AlignedAfter<B, A::Size> as IStable>::Size;
     type Align = <A::Align as Alignment>::Max<B::Align>;
-    type HasExactlyOneNiche = <A::HasExactlyOneNiche as ISaturatingAdd>::SaturatingAdd<
-        <AlignedAfter<B, A::Size> as IStable>::HasExactlyOneNiche,
-    >;
+    type HasExactlyOneNiche =
+        <<Self::Size as Unsigned>::Equal<<A::Size as Unsigned>::Add<B::Size>> as Bit>::SaddTernary<
+            <A::HasExactlyOneNiche as ISaturatingAdd>::SaturatingAdd<
+                <AlignedAfter<B, A::Size> as IStable>::HasExactlyOneNiche,
+            >,
+            Saturator,
+        >;
     type ContainsIndirections = <A::ContainsIndirections as Bit>::Or<B::ContainsIndirections>;
     #[cfg(feature = "experimental-ctypes")]
     type CType = ();
@@ -426,6 +430,7 @@ impl ISaturatingAdd for Saturator {
     type SaturatingAddB1 = Saturator;
     type SaturatingAdd<B: ISaturatingAdd> = Saturator;
 }
+#[derive(Default)]
 /// An Exception-like value that indicates a computation can never succeed.
 pub struct Saturator;
 
@@ -553,7 +558,10 @@ unsafe impl<T: IStable> IStable for Struct<T> {
     type ForbiddenValues = T::ForbiddenValues;
     type UnusedBits = <T::UnusedBits as IBitMask>::BitOr<
         <<tyeval!(<T::Size as Unsigned>::NextMultipleOf<T::Align> - T::Size) as IUnsignedBase>::PaddingBitMask as IBitMask>::Shift<T::Size>>;
-    type HasExactlyOneNiche = Saturator;
+    type HasExactlyOneNiche = <<T::Size as Unsigned>::Equal<Self::Size> as Bit>::SaddTernary<
+        T::HasExactlyOneNiche,
+        Saturator,
+    >;
     type ContainsIndirections = T::ContainsIndirections;
     #[cfg(feature = "experimental-ctypes")]
     type CType = ();

stabby/src/tests/layouts.rs

@@ -16,12 +16,12 @@ use core::num::{NonZeroU16, NonZeroU32, NonZeroU8};
 
 use crate as stabby;
 use stabby::tuple::{Tuple2, Tuple3, Tuple8};
-use stabby_abi::{typenum2::*, Array, End, Result};
+use stabby_abi::{istable::Saturator, typenum2::*, Array, End, IStable, Result};
 
 #[stabby::stabby]
-pub union UTest {
+pub union UnionTest {
     u8: u8,
-    usize: usize,
+    u64: u64,
 }
 #[stabby::stabby]
 pub union UTest2 {
@@ -88,23 +88,23 @@ pub enum SameFieldsFourTimes<T> {
 pub struct WeirdStructBadLayout {
     fields: FieldsC,
     no_fields: NoFields,
-    utest: UTest,
+    utest: UnionTest,
     u32: u32,
 }
 
 #[stabby::stabby]
 pub struct WeirdStructBadLayout2 {
     fields: FieldsC,
     no_fields: NoFields,
-    utest: UTest,
+    utest: UnionTest,
 }
 
 #[stabby::stabby]
 pub struct WeirdStruct {
     fields: FieldsC,
     no_fields: NoFields,
     u32: u32,
-    utest: UTest,
+    utest: UnionTest,
 }
 
 #[stabby::stabby]
@@ -117,9 +117,25 @@ pub struct Test {
     a: u32,
 }
 
+#[stabby::stabby]
+pub struct SingleNiche {
+    a: usize,
+    b: &'static u8,
+}
+#[stabby::stabby]
+pub struct EndPadding {
+    a: usize,
+    b: u8,
+}
+
 #[test]
 fn layouts() {
     use stabby::abi::istable::IForbiddenValues;
+    let _: B1 = <<SingleNiche as IStable>::HasExactlyOneNiche>::default();
+    let _: Saturator = <<EndPadding as IStable>::HasExactlyOneNiche>::default();
+    let _: B0 = <<Tuple3<u32, u32, u32> as IStable>::HasExactlyOneNiche>::default();
+    let _: Saturator = <<Tuple2<u8, u32> as IStable>::HasExactlyOneNiche>::default();
+    let _: Saturator = <<Test as IStable>::HasExactlyOneNiche>::default();
     macro_rules! test {
         () => {};
         ($t: ty, $unused: ty, $illegal: ty) => {
@@ -199,7 +215,7 @@ fn layouts() {
     test!(stabby::abi::Union<u8, ()>, End, End);
     test!(stabby::abi::Union<(), u8>, End, End);
     test!(stabby::result::Result<(), ()>, Array<U0, Ub11111110, End>, End);
-    test!(UTest, End, End);
+    test!(UnionTest, End, End);
     test!(FieldsC, Array<U1, UxFF, Array<U2, UxFF, Array<U3, UxFF, End>>>, End);
     test!(FieldsStabby, End, End);
     test!(MultiFieldsC, Array<U1, UxFF, End>, End);