Upgrade rust nightly toolchain & MSRV (#745)

Cargo.toml

@@ -36,7 +36,7 @@ include = [
     "flatbuffers/*.fbs",
 ]
 edition = "2021"
-rust-version = "1.76"
+rust-version = "1.81"
 
 [workspace.dependencies]
 libfuzzer-sys = "0.4"

rust-toolchain.toml

@@ -1,4 +1,4 @@
 [toolchain]
-channel = "nightly-2024-06-19"
+channel = "nightly-2024-09-04"
 components = ["rust-src", "rustfmt", "clippy"]
 profile = "minimal"

vortex-array/src/compute/unary/fill_forward.rs

@@ -3,6 +3,7 @@ use vortex_error::{vortex_err, VortexResult};
 use crate::{Array, ArrayDType};
 
 /// Trait for filling forward on an array, i.e., replacing nulls with the last non-null value.
+///
 /// If the array is non-nullable, it is returned as-is.
 /// If the array is entirely nulls, the fill forward operation returns an array of the same length, filled with the default value of the array's type.
 /// The DType of the returned array is the same as the input array; the Validity of the returned array is always either NonNullable or AllValid.

vortex-array/src/iter/mod.rs

@@ -58,6 +58,7 @@ pub trait Accessor<T>: Send + Sync {
 }
 
 /// Iterate over batches of compressed arrays, should help with writing vectorized code.
+///
 /// Note that it doesn't respect per-item validity, and the per-item `Validity` instance should be advised
 /// for correctness, must "high-performance" code will ignore the validity when doing work, and will only
 /// re-use it when reconstructing the result array.

vortex-array/src/metadata.rs

@@ -7,6 +7,7 @@ use serde::{Deserialize, Serialize};
 use vortex_error::{vortex_err, VortexResult};
 
 /// Dynamic trait used to represent opaque owned Array metadata
+///
 /// Note that this allows us to restrict the ('static + Send + Sync) requirement to just the
 /// metadata trait, and not the entire array trait. We require 'static so that we can downcast
 /// use the Any trait.

vortex-serde/src/layouts/pruning.rs

@@ -1,3 +1,6 @@
+// This code doesn't have usage outside of tests yet, remove once usage is added
+#![allow(dead_code)]
+
 use std::collections::hash_map::Entry;
 use std::sync::Arc;
 
@@ -8,7 +11,6 @@ use vortex_dtype::Nullability;
 use vortex_expr::{BinaryExpr, Column, Literal, Operator, VortexExpr};
 use vortex_scalar::Scalar;
 
-#[allow(dead_code)]
 pub struct PruningPredicate {
     expr: Arc<dyn VortexExpr>,
     stats_to_fetch: HashMap<Field, Vec<Stat>>,

vortex-serde/src/layouts/read/layouts.rs

@@ -42,11 +42,6 @@ impl FlatLayout {
             state: FlatLayoutState::Init,
         }
     }
-
-    #[allow(clippy::len_without_is_empty)]
-    pub fn len(&self) -> usize {
-        self.range.len()
-    }
 }
 
 impl Layout for FlatLayout {