Bump MSRV to 1.87 and nalgebra to the 0.34 release (#16045)

mtreinish · jakelishman · web-flow · commit 9fa17a332875 · 2026-04-16T13:50:33.000Z
* Bump MSRV to 1.87 and nalgebra to the 0.34 release

This commit updates nalgebra to the latest release 0.34 and also
increases our MSRV to the minimum version compatible with that nalgebra
release 1.87. Nalgebra 0.34 was release in July of 2025 and we didn't
upgrade at the time because we had just increased our msrv to 1.85 and
bumping it again would have been overly onerous. But since we're now
using nalgebra more in critical code paths (2q decomposition) it makes
sense to make this change now especially since rust 1.87 is over 1 year
old now (being release in March 2025).

The rust code changes made in this are to fix clippy warnings due to new
clippy rules being enabled with the higher msrv of 1.87.

* Update releasenotes/notes/msrv-187-fe3d9818f5c4103d.yaml

Co-authored-by: Jake Lishman &lt;jake@binhbar.com&gt;

---------

Co-authored-by: Jake Lishman &lt;jake@binhbar.com&gt;
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -5,7 +5,7 @@ resolver = "2"
 [workspace.package]
 version = "2.5.0-dev"
 edition = "2024"
-rust-version = "1.85"  # Keep in sync with README.md, rust-toolchain.toml, and tools/install_rust_msrv.sh
+rust-version = "1.87"  # Keep in sync with README.md, rust-toolchain.toml, and tools/install_rust_msrv.sh
 license = "Apache-2.0"
 
 # Shared dependencies that can be inherited.  This just helps a little with
@@ -20,7 +20,7 @@ indexmap.version = "2.10.0"
 hashbrown.version = "0.15.5"
 num-bigint = "0.4"
 num-complex = "0.4"
-nalgebra = "0.33"
+nalgebra = "0.34"
 faer = "0.24"
 numpy = "0.28"
 ndarray = "0.16"
diff --git a/README.md b/README.md
@@ -6,7 +6,7 @@
 [![Downloads](https://img.shields.io/pypi/dm/qiskit.svg)](https://pypi.org/project/qiskit/)
 [![Coverage Status](https://coveralls.io/repos/github/Qiskit/qiskit/badge.svg?branch=main)](https://coveralls.io/github/Qiskit/qiskit?branch=main)
 ![PyPI - Python Version](https://img.shields.io/pypi/pyversions/qiskit)
-[![Minimum rustc 1.85](https://img.shields.io/badge/rustc-1.85+-blue.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
+[![Minimum rustc 1.87](https://img.shields.io/badge/rustc-1.87+-blue.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
 [![Downloads](https://static.pepy.tech/badge/qiskit)](https://pepy.tech/project/qiskit)<!--- long-description-skip-end -->
 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.2583252.svg)](https://doi.org/10.5281/zenodo.2583252)
 
diff --git a/crates/circuit_library/src/entanglement.rs b/crates/circuit_library/src/entanglement.rs
@@ -87,7 +87,7 @@ fn shift_circular_alternating(
     let shifted = circular(num_qubits, block_size)
         .skip(split as usize)
         .chain(circular(num_qubits, block_size).take(split as usize));
-    if offset % 2 == 0 {
+    if offset.is_multiple_of(2) {
         Box::new(shifted)
     } else {
         // if the offset is odd, reverse the indices inside the qubit block (e.g. turn CX
diff --git a/crates/circuit_library/src/pauli_feature_map.rs b/crates/circuit_library/src/pauli_feature_map.rs
@@ -201,7 +201,7 @@ fn _default_reduce(parameters: Vec<Param>) -> Param {
         let acc = parameters.iter().fold(Param::Float(1.0), |acc, param| {
             multiply_params(acc, add_param(param, -PI))
         });
-        if parameters.len() % 2 == 0 {
+        if parameters.len().is_multiple_of(2) {
             acc
         } else {
             multiply_param(&acc, -1.0) // take care of parity
diff --git a/crates/circuit_library/src/suzuki_trotter.rs b/crates/circuit_library/src/suzuki_trotter.rs
@@ -36,7 +36,7 @@ pub fn suzuki_trotter_evolution(
     preserve_order: bool,
     insert_barriers: bool,
 ) -> Result<CircuitData, EvolutionError> {
-    if order > 1 && order % 2 != 0 || order == 0 {
+    if order > 1 && !order.is_multiple_of(2) || order == 0 {
         return Err(EvolutionError::OrderSymmetry(order));
     }
 
diff --git a/crates/quantum_info/src/sparse_pauli_op.rs b/crates/quantum_info/src/sparse_pauli_op.rs
@@ -383,7 +383,10 @@ impl MatrixCompressedPaulis {
                 // Technically this discards part of the storable data, but in practice, a dense
                 // operator with more than 32 qubits needs in the region of 1 ZiB memory.  We still use
                 // `u64` to help sparse-matrix construction, though.
-                let coeff = if (i_row as u32 & z_like as u32).count_ones() % 2 == 0 {
+                let coeff = if (i_row as u32 & z_like as u32)
+                    .count_ones()
+                    .is_multiple_of(2)
+                {
                     coeff
                 } else {
                     -coeff
diff --git a/crates/quantum_info/src/unitary_compose.rs b/crates/quantum_info/src/unitary_compose.rs
@@ -87,7 +87,7 @@ fn _einsum_matmul(
 ) -> Result<Array<Complex64, IxDyn>, &'static str> {
     let rank = tensor.ndim();
     let rank_mat = mat.ndim();
-    if rank_mat % 2 != 0 {
+    if !rank_mat.is_multiple_of(2) {
         return Err("Contracted matrix must have an even number of indices.");
     }
     // Get einsum indices for tensor
diff --git a/crates/synthesis/src/linear/pmh.rs b/crates/synthesis/src/linear/pmh.rs
@@ -31,7 +31,7 @@ fn _index(transpose: bool, i: usize, j: usize) -> (usize, usize) {
 
 fn _ceil_fraction(numerator: usize, denominator: usize) -> usize {
     let mut fraction = numerator / denominator;
-    if numerator % denominator > 0 {
+    if !numerator.is_multiple_of(denominator) {
         fraction += 1;
     }
     fraction
diff --git a/crates/synthesis/src/linear_phase/cx_cz_depth_lnn.rs b/crates/synthesis/src/linear_phase/cx_cz_depth_lnn.rs
@@ -150,7 +150,7 @@ fn _update_phase_schedule(
                     (k != i)
                         && (k != j)
                         && (order_comp[min(k, j)] < order_comp[i])
-                        && (phase_schedule[[min(k, j), max(k, j)]] % 4 != 0)
+                        && !phase_schedule[[min(k, j), max(k, j)]].is_multiple_of(4)
                 })
                 .collect();
 
diff --git a/crates/synthesis/src/linear_phase/cz_depth_lnn.rs b/crates/synthesis/src/linear_phase/cz_depth_lnn.rs
@@ -76,13 +76,13 @@ fn _create_patterns(n: usize) -> HashMap<(usize, usize), (usize, usize)> {
         return HashMap::from_iter((0..n).map(|i| ((0, i), (i, i))));
     }
 
-    let (pat1, pat2) = if n % 2 == 0 {
+    let (pat1, pat2) = if n.is_multiple_of(2) {
         (_even_pattern1(n), _even_pattern2(n))
     } else {
         (_odd_pattern1(n), _odd_pattern2(n))
     };
 
-    let ind = if n % 2 == 0 {
+    let ind = if n.is_multiple_of(2) {
         (2 * n - 4) / 2
     } else {
         (2 * n - 4) / 2 - 1
@@ -157,7 +157,7 @@ pub(super) fn synth_cz_depth_line_mr_inner(matrix: ArrayView2<bool>) -> (usize,
         s_gates = Array1::<usize>::zeros(num_qubits);
     }
 
-    if num_qubits % 2 == 0 {
+    if num_qubits.is_multiple_of(2) {
         let i = num_qubits / 2;
 
         for j in 0..num_qubits {
diff --git a/crates/synthesis/src/multi_controlled/mcx.rs b/crates/synthesis/src/multi_controlled/mcx.rs
@@ -685,7 +685,7 @@ fn synth_relative_mcx_n_dirty(num_controls: usize) -> Result<CircuitData, Circui
 ///
 /// A quantum circuit with :math:`n+1` qubits.
 fn increment_1_dirty(n: u32, flag_add: bool) -> PyResult<CircuitData> {
-    if n % 2 == 0 {
+    if n.is_multiple_of(2) {
         return Err(QiskitError::new_err(
             "increment_1_dirty_large requires an odd number of qubits.",
         ));
@@ -905,7 +905,7 @@ pub fn synth_mcx_noaux_hp24(num_controls: usize) -> PyResult<CircuitData> {
         // The construction described in Fig.8 of the paper works for all values of n and is better than the one
         // in Fig.7 when n<23.
 
-        if (n % 2 == 0) && (n >= 23) {
+        if n.is_multiple_of(2) && (n >= 23) {
             // This implements C^{n-1}(V) in Fig.7.
 
             // These implement U^{n-1}_{+1} and U^{n-1}_{-1} (last qubit is ancilla)
diff --git a/crates/synthesis/src/permutation/mod.rs b/crates/synthesis/src/permutation/mod.rs
diff --git a/releasenotes/notes/msrv-187-fe3d9818f5c4103d.yaml b/releasenotes/notes/msrv-187-fe3d9818f5c4103d.yaml
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
diff --git a/tools/install_rust_msrv.sh b/tools/install_rust_msrv.sh

Original file line number	Diff line number	Diff line change
`@@ -36,7 +36,7 @@ pub fn suzuki_trotter_evolution(`
`36`	`36`	`preserve_order: bool,`
`37`	`37`	`insert_barriers: bool,`
`38`	`38`	`) -> Result<CircuitData, EvolutionError> {`
`39`		`- if order > 1 && order % 2 != 0 \|\| order == 0 {`
	`39`	`+ if order > 1 && !order.is_multiple_of(2) \|\| order == 0 {`
`40`	`40`	`return Err(EvolutionError::OrderSymmetry(order));`
`41`	`41`	`}`
`42`	`42`
Original file line number	Diff line number	Diff line change
`@@ -87,7 +87,7 @@ fn _einsum_matmul(`
`87`	`87`	`) -> Result<Array<Complex64, IxDyn>, &'static str> {`
`88`	`88`	`let rank = tensor.ndim();`
`89`	`89`	`let rank_mat = mat.ndim();`
`90`		`- if rank_mat % 2 != 0 {`
	`90`	`+ if !rank_mat.is_multiple_of(2) {`
`91`	`91`	`return Err("Contracted matrix must have an even number of indices.");`
`92`	`92`	`}`
`93`	`93`	`// Get einsum indices for tensor`
Original file line number	Diff line number	Diff line change
`@@ -31,7 +31,7 @@ fn _index(transpose: bool, i: usize, j: usize) -> (usize, usize) {`
`31`	`31`
`32`	`32`	`fn _ceil_fraction(numerator: usize, denominator: usize) -> usize {`
`33`	`33`	`let mut fraction = numerator / denominator;`
`34`		`- if numerator % denominator > 0 {`
	`34`	`+ if !numerator.is_multiple_of(denominator) {`
`35`	`35`	`fraction += 1;`
`36`	`36`	`}`
`37`	`37`	`fraction`