From ef3c5a1e35fe9a1720d72129c2bfe6945cca2006 Mon Sep 17 00:00:00 2001
From: Toshiki Teramura <toshiki.teramura@gmail.com>
Date: Wed, 31 Aug 2022 21:40:40 +0900
Subject: [PATCH] Introduce VecAssumeInit to convert Vec<MaybeUninit<T>> to
 Vec<T>

---
 lax/src/lib.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lax/src/lib.rs b/lax/src/lib.rs
index 3fbe7643..7da313ff 100644
--- a/lax/src/lib.rs
+++ b/lax/src/lib.rs
@@ -156,6 +156,27 @@ impl_as_ptr!(MaybeUninit<f64>, f64);
 impl_as_ptr!(MaybeUninit<c32>, lapack_sys::__BindgenComplex<f32>);
 impl_as_ptr!(MaybeUninit<c64>, lapack_sys::__BindgenComplex<f64>);
 
+pub(crate) trait VecAssureInit {
+    type Target;
+    unsafe fn assure_init(self) -> Self::Target;
+}
+
+macro_rules! impl_vec_assure_init {
+    ($e:ty) => {
+        impl VecAssureInit for Vec<MaybeUninit<$e>> {
+            type Target = Vec<$e>;
+            unsafe fn assure_init(mut self) -> Self::Target {
+                Vec::from_raw_parts(self.as_mut_ptr() as *mut $e, self.len(), self.capacity())
+            }
+        }
+    };
+}
+
+impl_vec_assure_init!(f32);
+impl_vec_assure_init!(f64);
+impl_vec_assure_init!(c32);
+impl_vec_assure_init!(c64);
+
 /// Upper/Lower specification for seveal usages
 #[derive(Debug, Clone, Copy)]
 #[repr(u8)]