Finally figured out some trait nitty-gritty

nalgebra-lapack/src/schur.rs

@@ -153,15 +153,15 @@ where
     where
         DefaultAllocator: Allocator<Complex<T>, D>,
     {
-        let mut out = unsafe {
+        let mut out =
-            OVector::new_uninitialized_generic(self.t.data.shape().0, Const::<1>).assume_init()
+            unsafe { OVector::new_uninitialized_generic(self.t.data.shape().0, Const::<1>) };
-        };
 
         for i in 0..out.len() {
-            out[i] = Complex::new(self.re[i], self.im[i])
+            out[i] = MaybeUninit::new(Complex::new(self.re[i], self.im[i]));
         }
 
-        out
+        // Safety: all entries have been initialized.
+        unsafe { out.assume_init() }
     }
 }
 

src/base/alias.rs

@@ -1,3 +1,4 @@
+
 #[cfg(any(feature = "alloc", feature = "std"))]
 use crate::base::dimension::Dynamic;
 use crate::base::dimension::{U1, U2, U3, U4, U5, U6};

src/base/allocator.rs

@@ -1,6 +1,5 @@
 //! Abstract definition of a matrix data storage allocator.
 
-use std::any::Any;
 use std::mem::MaybeUninit;
 
 use crate::base::constraint::{SameNumberOfColumns, SameNumberOfRows, ShapeConstraint};
@@ -17,7 +16,7 @@ use crate::base::DefaultAllocator;
 ///
 /// Every allocator must be both static and dynamic. Though not all implementations may share the
 /// same `Buffer` type.
-pub trait Allocator<T, R: Dim, C: Dim = U1>: Any + Sized {
+pub trait Allocator<T, R: Dim, C: Dim = U1>: 'static + Sized {
     /// The type of buffer this allocator can instanciate.
     type Buffer: ContiguousStorageMut<T, R, C>;
 

src/base/construction.rs

@@ -30,16 +30,8 @@ use crate::base::{
 #[macro_export]
 macro_rules! unimplemented_or_uninitialized_generic {
     ($nrows:expr, $ncols:expr) => {{
-        #[cfg(feature="no_unsound_assume_init")] {
+        crate::base::Matrix::new_uninitialized_generic($nrows, $ncols)
-            // Some of the call sites need the number of rows and columns from this to infer a type, so
+    }};
-            // uninitialized memory is used to infer the type, as `T: Zero` isn't available at all callsites.
-            // This may technically still be UB even though the assume_init is dead code, but all callsites should be fixed before #556 is closed.
-            let typeinference_helper = crate::base::Matrix::new_uninitialized_generic($nrows, $ncols);
-            unimplemented!();
-            typeinference_helper.assume_init()
-        }
-        #[cfg(not(feature="no_unsound_assume_init"))] { crate::base::Matrix::new_uninitialized_generic($nrows, $ncols).assume_init() }
-    }}
 }
 
 /// # Generic constructors
@@ -78,7 +70,7 @@ where
     #[inline]
     pub fn zeros_generic(nrows: R, ncols: C) -> Self
     where
-        T: Zero,
+        T: Zero + Clone,
     {
         Self::from_element_generic(nrows, ncols, T::zero())
     }
@@ -98,22 +90,28 @@ where
     /// The order of elements in the slice must follow the usual mathematic writing, i.e.,
     /// row-by-row.
     #[inline]
-    pub fn from_row_slice_generic(nrows: R, ncols: C, slice: &[T]) -> Self {
+    pub fn from_row_slice_generic(nrows: R, ncols: C, slice: &[T]) -> Self
+    where
+        T: Clone,
+    {
         assert!(
             slice.len() == nrows.value() * ncols.value(),
             "Matrix init. error: the slice did not contain the right number of elements."
         );
 
-        let mut res = unsafe { crate::unimplemented_or_uninitialized_generic!(nrows, ncols) };
+        let mut res = Matrix::new_uninitialized_generic(nrows, ncols);
         let mut iter = slice.iter();
 
         for i in 0..nrows.value() {
             for j in 0..ncols.value() {
-                unsafe { *res.get_unchecked_mut((i, j)) = iter.next().unwrap().inlined_clone() }
+                unsafe {
+                    *res.get_unchecked_mut((i, j)) = MaybeUninit::new(iter.next().unwrap().clone());
+                }
             }
         }
 
-        res
+        // Safety: all entries have been initialized.
+        unsafe { res.assume_init() }
     }
 
     /// Creates a matrix with its elements filled with the components provided by a slice. The
@@ -130,15 +128,18 @@ where
     where
         F: FnMut(usize, usize) -> T,
     {
-        let mut res: Self = unsafe { crate::unimplemented_or_uninitialized_generic!(nrows, ncols) };
+        let mut res = Matrix::new_uninitialized_generic(nrows, ncols);
 
         for j in 0..ncols.value() {
             for i in 0..nrows.value() {
-                unsafe { *res.get_unchecked_mut((i, j)) = f(i, j) }
+                unsafe {
+                    *res.get_unchecked_mut((i, j)) = MaybeUninit::new(f(i, j));
+                }
             }
         }
 
-        res
+        // Safety: all entries have been initialized.
+        unsafe { Matrix::assume_init(res) }
     }
 
     /// Creates a new identity matrix.
@@ -160,7 +161,7 @@ where
     #[inline]
     pub fn from_diagonal_element_generic(nrows: R, ncols: C, elt: T) -> Self
     where
-        T: Zero + One,
+        T: Zero + One+Clone,
     {
         let mut res = Self::zeros_generic(nrows, ncols);
 
@@ -178,7 +179,7 @@ where
     #[inline]
     pub fn from_partial_diagonal_generic(nrows: R, ncols: C, elts: &[T]) -> Self
     where
-        T: Zero,
+        T: Zero+Clone,
     {
         let mut res = Self::zeros_generic(nrows, ncols);
         assert!(
@@ -187,7 +188,7 @@ where
         );
 
         for (i, elt) in elts.iter().enumerate() {
-            unsafe { *res.get_unchecked_mut((i, i)) = elt.inlined_clone() }
+            unsafe { *res.get_unchecked_mut((i, i)) = elt.clone() }
         }
 
         res
@@ -211,7 +212,7 @@ where
     /// ```
     #[inline]
     pub fn from_rows<SB>(rows: &[Matrix<T, Const<1>, C, SB>]) -> Self
-    where
+    where T:Clone,
         SB: Storage<T, Const<1>, C>,
     {
         assert!(!rows.is_empty(), "At least one row must be given.");
@@ -231,7 +232,7 @@ where
 
         // TODO: optimize that.
         Self::from_fn_generic(R::from_usize(nrows), C::from_usize(ncols), |i, j| {
-            rows[i][(0, j)].inlined_clone()
+            rows[i][(0, j)].clone()
         })
     }
 
@@ -253,7 +254,7 @@ where
     /// ```
     #[inline]
     pub fn from_columns<SB>(columns: &[Vector<T, R, SB>]) -> Self
-    where
+    where T:Clone,
         SB: Storage<T, R>,
     {
         assert!(!columns.is_empty(), "At least one column must be given.");
@@ -273,7 +274,7 @@ where
 
         // TODO: optimize that.
         Self::from_fn_generic(R::from_usize(nrows), C::from_usize(ncols), |i, j| {
-            columns[j][i].inlined_clone()
+            columns[j][i].clone()
         })
     }
 
@@ -458,7 +459,7 @@ macro_rules! impl_constructors(
         #[inline]
         pub fn zeros($($args: usize),*) -> Self
         where
-            T: Zero
+            T: Zero + Clone
         {
             Self::zeros_generic($($gargs),*)
         }

src/base/conversion.rs

@@ -3,6 +3,7 @@ use alloc::vec::Vec;
 use simba::scalar::{SubsetOf, SupersetOf};
 use std::borrow::{Borrow, BorrowMut};
 use std::convert::{AsMut, AsRef, From, Into};
+use std::mem::MaybeUninit;
 
 use simba::simd::{PrimitiveSimdValue, SimdValue};
 
@@ -44,17 +45,19 @@ where
         let nrows2 = R2::from_usize(nrows);
         let ncols2 = C2::from_usize(ncols);
 
-        let mut res: OMatrix<T2, R2, C2> =
+        let mut res = OMatrix::<T2, R2, C2>::new_uninitialized_generic(nrows2, ncols2);
-            unsafe { crate::unimplemented_or_uninitialized_generic!(nrows2, ncols2) };
+
         for i in 0..nrows {
             for j in 0..ncols {
                 unsafe {
-                    *res.get_unchecked_mut((i, j)) = T2::from_subset(self.get_unchecked((i, j)))
+                    *res.get_unchecked_mut((i, j)) =
+                        MaybeUninit::new(T2::from_subset(self.get_unchecked((i, j))));
                 }
             }
         }
 
-        res
+        // Safety: all entries have been initialized.
+        unsafe { Matrix::assume_init(res) }
     }
 
     #[inline]
@@ -68,16 +71,18 @@ where
         let nrows = R1::from_usize(nrows2);
         let ncols = C1::from_usize(ncols2);
 
-        let mut res: Self = unsafe { crate::unimplemented_or_uninitialized_generic!(nrows, ncols) };
+        let mut res = OMatrix::new_uninitialized_generic(nrows, ncols);
         for i in 0..nrows2 {
             for j in 0..ncols2 {
                 unsafe {
-                    *res.get_unchecked_mut((i, j)) = m.get_unchecked((i, j)).to_subset_unchecked()
+                    *res.get_unchecked_mut((i, j)) =
+                        MaybeUninit::new(m.get_unchecked((i, j)).to_subset_unchecked());
                 }
             }
         }
 
-        res
+        // Safety: all entries have been initialized.
+        unsafe { res.assume_init() }
     }
 }
 

src/base/default_allocator.rs

@@ -68,7 +68,7 @@ impl<T, const R: usize, const C: usize> Allocator<T, Const<R>, Const<C>> for Def
         );
 
         // Safety: we have initialized all entries.
-        unsafe { Self::assume_init(res) }
+        unsafe { <Self as Allocator<T, Const<R>, Const<C>>>::assume_init(res) }
     }
 }
 

src/base/matrix.rs

@@ -34,6 +34,10 @@ use crate::{ArrayStorage, SMatrix, SimdComplexField};
 #[cfg(any(feature = "std", feature = "alloc"))]
 use crate::{DMatrix, DVector, Dynamic, VecStorage};
 
+/// An uninitialized matrix.
+pub type UninitMatrix<T, R, C> =
+    Matrix<MaybeUninit<T>, R, C, <DefaultAllocator as Allocator<T, R, C>>::UninitBuffer>;
+
 /// A square matrix.
 pub type SquareMatrix<T, D, S> = Matrix<T, D, D, S>;
 
@@ -347,39 +351,34 @@ impl<T, R, C, S> Matrix<T, R, C, S> {
     }
 }
 
-impl<T, R: Dim, C: Dim, S> Matrix<T, R, C, S>
+impl<T, R: Dim, C: Dim>
+    Matrix<MaybeUninit<T>, R, C, <DefaultAllocator as Allocator<T, R, C>>::UninitBuffer>
 where
-    S: Storage<T, R, C>,
+    DefaultAllocator: Allocator<T, R, C>,
-    DefaultAllocator: Allocator<T, R, C, Buffer = S>,
 {
     /// Allocates a matrix with the given number of rows and columns without initializing its content.
-    pub fn new_uninitialized_generic(
+    ///
-        nrows: R,
+    /// Note: calling `Self::new_uninitialized_generic` is often **not** what you want to do. Consider
-        ncols: C,
+    /// calling `Matrix::new_uninitialized_generic` instead.
-    ) -> Matrix<MaybeUninit<T>, R, C, <DefaultAllocator as Allocator<T, R, C>>::UninitBuffer> {
+    pub fn new_uninitialized_generic(nrows: R, ncols: C) -> Self {
-        Matrix {
+        Self {
             data: <DefaultAllocator as Allocator<T, R, C>>::allocate_uninitialized(nrows, ncols),
             _phantoms: PhantomData,
         }
     }
 }
 
-impl<T, R: Dim, C: Dim, S> Matrix<MaybeUninit<T>, R, C, S>
+impl<T, R: Dim, C: Dim>
+    Matrix<MaybeUninit<T>, R, C, <DefaultAllocator as Allocator<T, R, C>>::UninitBuffer>
 where
-    S: Storage<T, R, C>,
+    DefaultAllocator: Allocator<T, R, C>,
-    DefaultAllocator: Allocator<T, R, C, Buffer = S>,
 {
     /// Assumes a matrix's entries to be initialized. This operation should be near zero-cost.
     pub unsafe fn assume_init(
-        uninit: Matrix<
+        self,
-            MaybeUninit<T>,
+    ) -> Matrix<T, R, C, <DefaultAllocator as Allocator<T, R, C>>::Buffer> {
-            R,
-            C,
-            <DefaultAllocator as Allocator<T, R, C>>::UninitBuffer,
-        >,
-    ) -> Matrix<T, R, C, S> {
         Matrix {
-            data: <DefaultAllocator as Allocator<T, R, C>>::assume_init(uninit.data),
+            data: <DefaultAllocator as Allocator<T, R, C>>::assume_init(self.data),
             _phantoms: PhantomData,
         }
     }
@@ -654,24 +653,25 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
         let nrows: SameShapeR<R, R2> = Dim::from_usize(nrows);
         let ncols: SameShapeC<C, C2> = Dim::from_usize(ncols);
 
-        let mut res: MatrixSum<T, R, C, R2, C2> =
+        let mut res = Matrix::new_uninitialized_generic(nrows, ncols);
-            unsafe { crate::unimplemented_or_uninitialized_generic!(nrows, ncols) };
 
         // TODO: use copy_from
         for j in 0..res.ncols() {
             for i in 0..res.nrows() {
                 unsafe {
-                    *res.get_unchecked_mut((i, j)) = self.get_unchecked((i, j)).clone();
+                    *res.get_unchecked_mut((i, j)) =
+                        MaybeUninit::new(self.get_unchecked((i, j)).clone());
                 }
             }
         }
 
-        res
+        unsafe { Matrix::assume_init(res) }
     }
 
-    /// Transposes `self` and store the result into `out`.
+    /// Transposes `self` and store the result into `out`, which will become
+    /// fully initialized.
     #[inline]
-    pub fn transpose_to<R2: Dim, C2: Dim, SB>(&self, out: &mut Matrix<T, R2, C2, SB>)
+    pub fn transpose_to<R2: Dim, C2: Dim, SB>(&self, out: &mut Matrix<MaybeUninit<T>, R2, C2, SB>)
     where
         T: Clone,
         SB: StorageMut<T, R2, C2>,
@@ -687,7 +687,8 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
         for i in 0..nrows {
             for j in 0..ncols {
                 unsafe {
-                    *out.get_unchecked_mut((j, i)) = self.get_unchecked((i, j)).clone();
+                    *out.get_unchecked_mut((j, i)) =
+                        MaybeUninit::new(self.get_unchecked((i, j)).clone());
                 }
             }
         }
@@ -702,17 +703,18 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
         DefaultAllocator: Allocator<T, C, R>,
     {
         let (nrows, ncols) = self.data.shape();
-
+        let mut res = OMatrix::new_uninitialized_generic(ncols, nrows);
-        unsafe {
-            let mut res = crate::unimplemented_or_uninitialized_generic!(ncols, nrows);
         self.transpose_to(&mut res);
 
-            res
+        unsafe {
+            // Safety: res is now fully initialized due to the guarantees of  transpose_to.
+            res.assume_init()
         }
     }
 }
 
 /// # Elementwise mapping and folding
+// Todo: maybe make ref versions of these methods that can be used when T is expensive to clone?
 impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
     /// Returns a matrix containing the result of `f` applied to each of its entries.
     #[inline]
@@ -724,19 +726,19 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
     {
         let (nrows, ncols) = self.data.shape();
 
-        let mut res: OMatrix<T2, R, C> =
+        let mut res = OMatrix::new_uninitialized_generic(nrows, ncols);
-            unsafe { crate::unimplemented_or_uninitialized_generic!(nrows, ncols) };
 
         for j in 0..ncols.value() {
             for i in 0..nrows.value() {
                 unsafe {
                     let a = self.data.get_unchecked(i, j).clone();
-                    *res.data.get_unchecked_mut(i, j) = f(a)
+                    *res.data.get_unchecked_mut(i, j) = MaybeUninit::new(f(a));
                 }
             }
         }
 
-        res
+        // Safety: all entries have been initialized.
+        unsafe { res.assume_init() }
     }
 
     /// Cast the components of `self` to another type.
@@ -821,8 +823,7 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
     {
         let (nrows, ncols) = self.data.shape();
 
-        let mut res: OMatrix<N3, R, C> =
+        let mut res = OMatrix::<N3, R, C>::new_uninitialized_generic(nrows, ncols);
-            unsafe { crate::unimplemented_or_uninitialized_generic!(nrows, ncols) };
 
         assert_eq!(
             (nrows.value(), ncols.value()),
@@ -835,12 +836,13 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
                 unsafe {
                     let a = self.data.get_unchecked(i, j).clone();
                     let b = rhs.data.get_unchecked(i, j).clone();
-                    *res.data.get_unchecked_mut(i, j) = f(a, b)
+                    *res.data.get_unchecked_mut(i, j) = MaybeUninit::new(f(a, b));
                 }
             }
         }
 
-        res
+        // Safety: all entries have been initialized.
+        unsafe { res.assume_init() }
     }
 
     /// Returns a matrix containing the result of `f` applied to each entries of `self` and
@@ -862,8 +864,7 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
     {
         let (nrows, ncols) = self.data.shape();
 
-        let mut res: OMatrix<N4, R, C> =
+        let mut res = OMatrix::new_uninitialized_generic(nrows, ncols);
-            unsafe { crate::unimplemented_or_uninitialized_generic!(nrows, ncols) };
 
         assert_eq!(
             (nrows.value(), ncols.value()),
@@ -882,12 +883,13 @@ impl<T, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
                     let a = self.data.get_unchecked(i, j).clone();
                     let b = b.data.get_unchecked(i, j).clone();
                     let c = c.data.get_unchecked(i, j).clone();
-                    *res.data.get_unchecked_mut(i, j) = f(a, b, c)
+                    *res.data.get_unchecked_mut(i, j) = MaybeUninit::new(f(a, b, c));
                 }
             }
         }
 
-        res
+        // Safety: all entries have been initialized.
+        unsafe { res.assume_init() }
     }
 
     /// Folds a function `f` on each entry of `self`.
@@ -1322,7 +1324,7 @@ impl<T, D: Dim, S: StorageMut<T, D, D>> Matrix<T, D, D, S> {
 impl<T: SimdComplexField, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S> {
     /// Takes the adjoint (aka. conjugate-transpose) of `self` and store the result into `out`.
     #[inline]
-    pub fn adjoint_to<R2, C2, SB>(&self, out: &mut Matrix<T, R2, C2, SB>)
+    pub fn adjoint_to<R2, C2, SB>(&self, out: &mut Matrix<MaybeUninit<T>, R2, C2, SB>)
     where
         R2: Dim,
         C2: Dim,
@@ -1339,7 +1341,8 @@ impl<T: SimdComplexField, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S
         for i in 0..nrows {
             for j in 0..ncols {
                 unsafe {
-                    *out.get_unchecked_mut((j, i)) = self.get_unchecked((i, j)).simd_conjugate();
+                    *out.get_unchecked_mut((j, i)) =
+                        MaybeUninit::new(self.get_unchecked((i, j)).simd_conjugate());
                 }
             }
         }
@@ -1355,8 +1358,7 @@ impl<T: SimdComplexField, R: Dim, C: Dim, S: Storage<T, R, C>> Matrix<T, R, C, S
         let (nrows, ncols) = self.data.shape();
 
         unsafe {
-            let mut res: OMatrix<_, C, R> =
+            let mut res = OMatrix::new_uninitialized_generic(ncols, nrows);
-                crate::unimplemented_or_uninitialized_generic!(ncols, nrows);
             self.adjoint_to(&mut res);
 
             res
@@ -1480,7 +1482,7 @@ impl<T, D: Dim, S: Storage<T, D, D>> SquareMatrix<T, D, S> {
     pub fn diagonal(&self) -> OVector<T, D>
     where
         T: Clone,
-        DefaultAllocator: Allocator<T, D> + Allocator<MaybeUninit<T>, D>,
+        DefaultAllocator: Allocator<T, D>,
     {
         self.map_diagonal(|e| e)
     }
@@ -1493,7 +1495,7 @@ impl<T, D: Dim, S: Storage<T, D, D>> SquareMatrix<T, D, S> {
     pub fn map_diagonal<T2: Clone>(&self, mut f: impl FnMut(T) -> T2) -> OVector<T2, D>
     where
         T: Clone,
-        DefaultAllocator: Allocator<T2, D> + Allocator<MaybeUninit<T2>, D>,
+        DefaultAllocator: Allocator<T2, D>,
     {
         assert!(
             self.is_square(),

src/linalg/schur.rs

@@ -297,10 +297,10 @@ where
     /// Computes the complex eigenvalues of the decomposed matrix.
     fn do_complex_eigenvalues(
         t: &OMatrix<T, D, D>,
-        out: &mut OVector<MaybeUninit<NumComplex<T>>, D>,
+        out: &mut OVector<NumComplex<T>, D>,
     ) where
         T: RealField,
-        DefaultAllocator: Allocator<MaybeUninit<NumComplex<T>>, D>,
+        DefaultAllocator: Allocator<NumComplex<T>, D>,
     {
         let dim = t.nrows();
         let mut m = 0;

src/sparse/cs_matrix.rs

@@ -263,6 +263,8 @@ where
     /// `nvals` possible non-zero values.
     pub fn new_uninitialized_generic(nrows: R, ncols: C, nvals: usize) -> Self {
         let mut i = Vec::with_capacity(nvals);
+
+        //BEEP BEEP!!!! UNDEFINED BEHAVIOR ALERT!!! BEEP BEEEP!!!
         unsafe {
             i.set_len(nvals);
         }