add regression test

src/test/rustdoc/issue-52873.rs

@@ -0,0 +1,171 @@
+// Regression test for #52873. We used to ICE due to unexpected
+// overflows when checking for "blanket impl inclusion".
+
+use std::marker::PhantomData;
+use std::cmp::Ordering;
+use std::ops::{Add, Mul};
+
+pub type True = B1;
+pub type False = B0;
+pub type U0 = UTerm;
+pub type U1 = UInt<UTerm, B1>;
+
+pub trait NonZero {}
+
+pub trait Bit {
+}
+
+pub trait Unsigned {
+}
+
+#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy, Hash, Debug, Default)]
+pub struct B0;
+
+impl B0 {
+    #[inline]
+    pub fn new() -> B0 {
+        B0
+    }
+}
+
+#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy, Hash, Debug, Default)]
+pub struct B1;
+
+impl B1 {
+    #[inline]
+    pub fn new() -> B1 {
+        B1
+    }
+}
+
+impl Bit for B0 {
+}
+
+impl Bit for B1 {
+}
+
+impl NonZero for B1 {}
+
+pub trait PrivatePow<Y, N> {
+    type Output;
+}
+pub type PrivatePowOut<A, Y, N> = <A as PrivatePow<Y, N>>::Output;
+
+pub type Add1<A> = <A as Add<::B1>>::Output;
+pub type Prod<A, B> = <A as Mul<B>>::Output;
+pub type Square<A> = <A as Mul>::Output;
+pub type Sum<A, B> = <A as Add<B>>::Output;
+
+#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy, Hash, Debug, Default)]
+pub struct UTerm;
+
+impl UTerm {
+    #[inline]
+    pub fn new() -> UTerm {
+        UTerm
+    }
+}
+
+impl Unsigned for UTerm {
+}
+
+#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy, Hash, Debug, Default)]
+pub struct UInt<U, B> {
+    _marker: PhantomData<(U, B)>,
+}
+
+impl<U: Unsigned, B: Bit> UInt<U, B> {
+    #[inline]
+    pub fn new() -> UInt<U, B> {
+        UInt {
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl<U: Unsigned, B: Bit> Unsigned for UInt<U, B> {
+}
+
+impl<U: Unsigned, B: Bit> NonZero for UInt<U, B> {}
+
+impl Add<B0> for UTerm {
+    type Output = UTerm;
+    fn add(self, _: B0) -> Self::Output {
+        UTerm
+    }
+}
+
+impl<U: Unsigned, B: Bit> Add<B0> for UInt<U, B> {
+    type Output = UInt<U, B>;
+    fn add(self, _: B0) -> Self::Output {
+        UInt::new()
+    }
+}
+
+impl<U: Unsigned> Add<U> for UTerm {
+    type Output = U;
+    fn add(self, _: U) -> Self::Output {
+        unsafe { ::std::mem::uninitialized() }
+    }
+}
+
+impl<U: Unsigned, B: Bit> Mul<B0> for UInt<U, B> {
+    type Output = UTerm;
+    fn mul(self, _: B0) -> Self::Output {
+        UTerm
+    }
+}
+
+impl<U: Unsigned, B: Bit> Mul<B1> for UInt<U, B> {
+    type Output = UInt<U, B>;
+    fn mul(self, _: B1) -> Self::Output {
+        UInt::new()
+    }
+}
+
+impl<U: Unsigned> Mul<U> for UTerm {
+    type Output = UTerm;
+    fn mul(self, _: U) -> Self::Output {
+        UTerm
+    }
+}
+
+impl<Ul: Unsigned, B: Bit, Ur: Unsigned> Mul<UInt<Ur, B>> for UInt<Ul, B0>
+where
+    Ul: Mul<UInt<Ur, B>>,
+{
+    type Output = UInt<Prod<Ul, UInt<Ur, B>>, B0>;
+    fn mul(self, _: UInt<Ur, B>) -> Self::Output {
+        unsafe { ::std::mem::uninitialized() }
+    }
+}
+
+pub trait Pow<Exp> {
+    type Output;
+}
+
+impl<X: Unsigned, N: Unsigned> Pow<N> for X
+where
+    X: PrivatePow<U1, N>,
+{
+    type Output = PrivatePowOut<X, U1, N>;
+}
+
+impl<Y: Unsigned, X: Unsigned> PrivatePow<Y, U0> for X {
+    type Output = Y;
+}
+
+impl<Y: Unsigned, X: Unsigned> PrivatePow<Y, U1> for X
+where
+    X: Mul<Y>,
+{
+    type Output = Prod<X, Y>;
+}
+
+impl<Y: Unsigned, U: Unsigned, B: Bit, X: Unsigned> PrivatePow<Y, UInt<UInt<U, B>, B0>> for X
+where
+    X: Mul,
+    Square<X>: PrivatePow<Y, UInt<U, B>>,
+{
+    type Output = PrivatePowOut<Square<X>, Y, UInt<U, B>>;
+}