chore(toolchain): bump ndarray to Rust 1.95.0 + manual_checked_ops fix

Aligns ndarray MSRV with the rest of the AdaWorldAPI stack (bevy already
on 1.95 for edition 2024, lance-graph bumped in a parallel PR). Single
rustc version across {ndarray, bevy, lance-graph, MedCare-rs} —
removes the `rustup run 1.95.0 …` vs default-toolchain confusion in
local dev and the bevy smoke-test CI.

Changes:
- `rust-toolchain.toml`: channel 1.94.1 → 1.95.0
- `Cargo.toml`: rust-version "1.94" → "1.95"
- `.github/workflows/ci.yaml`: MSRV / BLAS_MSRV env 1.94.0 → 1.95.0;
  clippy matrix + dtolnay/rust-toolchain pin 1.94.1 → 1.95.0; updated
  three explanatory comments that referenced the old pin.
- `src/impl_owned_array.rs::into_scalar`: fix the ONE 1.95 clippy lint
  that fires on this codebase — `clippy::manual_checked_ops` wants
  `checked_div` instead of the manual `if size == 0` + division. The
  fix is `(first - base).checked_div(size).unwrap_or(0)`; the existing
  `size == 0` guard above already handles the divisor-is-zero case, so
  the unwrap is unreachable in practice. Comment explains why.

Test surface (post-bump, 1.95.0):
  cargo test --features rayon --lib: 1788 passed, 36 ignored, 0 failed
  cargo clippy --features rayon --lib -- -D warnings: clean

Signal mining:
- New file `.claude/board/UNUSED_INVENTORY_1.95.md` catalogues 36
  `#[allow(dead_code|unused)]` suppression sites in the lib. Split into
  9 "likely actionable" (A1-A9: stale Rust 1.64 imports, phantom
  SimdTier variants already flagged by round-1 audit, dead clam code)
  + 27 "documented scaffolding" (B1-B10: cfg-conditional imports, rayon
  gates, no_std polyfill helpers, doc-link helpers). Provides a
  ready-made follow-up backlog without bundling the cleanup into this
  bump PR.

Companion: lance-graph parallel PR bumps to 1.95 the same way.

Author: claude

.claude/board/UNUSED_INVENTORY_1.95.md

@@ -0,0 +1,60 @@
+# Unused / Allow-suppressed Inventory — 1.95 sweep
+
+> **Captured:** 2026-05-13 while bumping ndarray master to Rust 1.95.0.
+> **Source:** `grep -rn "#\[allow(dead_code\|#\[allow(unused" src/` (lib only).
+> **Purpose:** signal mining — each entry below is a piece of code that
+> compiles but is allowed to be unused. Some are legitimate scaffolding
+> (rayon-gated, no_std polyfill, hot-swap reserves), some are actionable
+> (Rust-1.64 compatibility imports that 1.95 likely doesn't need, phantom
+> tier variants flagged by the round-1 audit fleet).
+
+## Categorization
+
+### A — Likely actionable (real "API drift" candidates)
+
+| # | Site | Suppression | Why interesting |
+|---|---|---|---|
+| A1 | `src/impl_owned_array.rs:7` | `unused_imports // Needed for Rust 1.64` | We just bumped to 1.95. The 1.64-era workaround is almost certainly stale. **Action:** remove the suppression, see if the import is still needed; if not, drop it. |
+| A2 | `src/iterators/mod.rs:24` | `unused_imports // Needed for Rust 1.64` | Same as A1. |
+| A3 | `src/hpc/simd_dispatch.rs:47` | `dead_code` on `SimdTier::WasmSimd128` (and likely `Sse2`) | **Flagged by round-1 audit agent #6**: `SimdTier::Sse2` is never selected in `detect()`; no SSE2 wrapper functions exist. Phantom variants. **Action:** delete or wire. |
+| A4 | `src/hpc/clam.rs:928` | `dead_code` | CLAM cluster code. **Action:** verify if the suppressed fn is reachable through any public CLAM call path; if not, delete. |
+| A5 | `src/hpc/clam_compress.rs:141` | `dead_code` | Same family as A4. |
+| A6 | `src/hpc/jitson/scan_config.rs:144` | `dead_code` | jitson scan-config. Probably scaffolding for an unfinished feature; needs PR-author review. |
+| A7 | `src/impl_ref_types.rs:364` | `dead_code` | ndarray ref type helper. |
+| A8 | `src/backend/native.rs:376`, `:423` | `dead_code` (×2) | Backend kernel helpers possibly only used by feature-gated paths. |
+| A9 | `src/hpc/packed.rs:29`, `:42` | `unused_variables` (×2) | Variables defined but unused. Either rename to `_x` for explicit "ignored", or wire them in. |
+
+### B — Documented scaffolding (intentional, leave)
+
+| # | Site | Suppression | Justification |
+|---|---|---|---|
+| B1 | `src/simd.rs:15,31,48,96,110,126,1612,1658,1672` (×9) | `dead_code` | Tier enum variants for cross-arch builds (only some platforms use all variants) + no_std `LazyLock` polyfill helpers. |
+| B2 | `src/split_at.rs:11` | `dead_code // used only when Rayon support is enabled` | Self-documented. |
+| B3 | `src/hpc/jitson_cranelift/engine.rs:130` | `dead_code // retained for future hot-swap / eviction by FuncId` | Self-documented. |
+| B4 | `src/data_repr.rs:11`, `src/data_traits.rs:11`, `src/impl_constructors.rs:37`, `src/impl_methods.rs:13`, `src/free_functions.rs:13`, `src/impl_views/conversions.rs:10` | `unused_imports` | Conditional-cfg imports needed under some feature combinations. |
+| B5 | `src/parallel/mod.rs:120,122` | `unused_imports // used by rustdoc links` | Self-documented. |
+| B6 | `src/simd_neon.rs:1721` | `unused_macros` | NEON macros only used on aarch64. |
+| B7 | `src/zip/mod.rs:424,715` | `dead_code` / `unused` | Zip iterator scaffolding. |
+| B8 | `src/backend/native.rs:20` | `dead_code` | Backend kernel scaffold. |
+| B9 | `src/doc/ndarray_for_numpy_users/mod.rs:750` | `unused_imports` | Doc example. |
+| B10 | `src/itertools.rs:90` | (inside a doc-comment example) | Not real code. |
+
+## Suggested follow-ups (post-1.95 bump)
+
+- **A1, A2 (Rust 1.64 compat sweep):** remove the suppression, attempt build, drop the import if no longer needed. Likely a 2-line change × 2 files.
+- **A3 (phantom SimdTier variants):** the round-1 audit fleet already flagged this. Pair with the round-3 cosmetic-SIMD consumer fleet — they'll touch `simd_dispatch.rs` anyway.
+- **A4, A5 (clam dead_code):** needs domain owner review. Worth flagging in a CLAM-related PR; not urgent.
+- **A6 (jitson scan_config):** check INTEGRATION_PLANS — if jitson is still active, wire; if archived, delete.
+- **A7, A8, A9:** small-scope per-site review; aggregate into a "dead-code cleanup" PR.
+
+## What this PR (1.95 bump) does NOT touch
+
+This file is **signal mining only**. The 1.95 bump PR itself:
+- Bumps `rust-toolchain.toml` → 1.95.0
+- Bumps `Cargo.toml` `rust-version` → "1.95"
+- Bumps `MSRV` / `BLAS_MSRV` env in ci.yaml → 1.95.0
+- Fixes the ONE 1.95 clippy lint that fires (`clippy::manual_checked_ops`
+  in `impl_owned_array.rs::into_scalar`)
+
+The 36 suppression sites are pre-existing and persist after the bump.
+Cleaning them up is the follow-up work surfaced by this inventory.

.github/workflows/ci.yaml

@@ -21,8 +21,8 @@ env:
   # `LazyLock<Tier>` detection means one binary, all ISAs. Jobs that
   # specifically need a higher target-cpu can opt in via per-job env.
   RUSTFLAGS: "-D warnings"
-  MSRV: 1.94.0
-  BLAS_MSRV: 1.94.0
+  MSRV: 1.95.0
+  BLAS_MSRV: 1.95.0
 
 jobs:
   pass-msrv:
@@ -41,15 +41,18 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        # Pinned to 1.94.1 to match `rust-toolchain.toml`. Auto-tracking
-        # `stable` would silently bump to 1.95 and start rejecting code
-        # on lints like `clippy::unnecessary_sort_by` that 1.94 accepted.
+        # Pinned to 1.95.0 to match `rust-toolchain.toml`. The workspace
+        # bumped from 1.94.1 → 1.95.0 in commit
+        # https://github.com/AdaWorldAPI/ndarray (this PR) to align with
+        # bevy (edition 2024 → 1.95 MSRV) and lance-graph. 1.95 added the
+        # `clippy::manual_checked_ops` lint which fires on
+        # `impl_owned_array.rs::into_scalar` — fixed in this same PR.
         rust:
-          - "1.94.1"
+          - "1.95.0"
     name: clippy/${{ matrix.rust }}
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.94.1
+      - uses: dtolnay/rust-toolchain@1.95.0
         with:
           components: clippy
       - uses: Swatinem/rust-cache@v2
@@ -77,7 +80,7 @@ jobs:
       # The format job MUST use nightly rustfmt for the project's chosen
       # style to be enforceable.
       #
-      # The compile + clippy jobs stay on 1.94.1 (pinned in
+      # The compile + clippy jobs stay on 1.95.0 (pinned in
       # `rust-toolchain.toml`) — only this fmt job needs nightly.
       - uses: dtolnay/rust-toolchain@nightly
         with:
@@ -101,7 +104,7 @@ jobs:
         with:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.target }}
-      # rust-toolchain.toml pins 1.94.1 — install the cross-compile target
+      # rust-toolchain.toml pins 1.95.0 — install the cross-compile target
       # for that toolchain too, since dtolnay/rust-toolchain only installs
       # for the matrix value which may differ from the pinned version.
       - run: rustup target add ${{ matrix.target }}

Cargo.toml

@@ -3,7 +3,7 @@
 name = "ndarray"
 version = "0.17.2"
 edition = "2021"
-rust-version = "1.94"
+rust-version = "1.95"
 authors = [
   "Ulrik Sverdrup \"bluss\"",
   "Jim Turner"

rust-toolchain.toml

@@ -1,8 +1,10 @@
 [toolchain]
-channel = "1.94.1"
-# Pinned to 1.94.1 (latest 1.94 patch, 2026-03-25). 1.95 turned several
-# previously-safe patterns into denied lints (e.g. unnecessary_sort_by)
-# without sufficient value to justify the churn — bump explicitly when
-# a future version is reviewed, never auto-track stable. Mirrors the
-# pin in lance-graph, smb-office-rs, and MedCare-rs.
+channel = "1.95.0"
+# Pinned to 1.95.0 (2026-04-14). Aligns ndarray with the rest of the
+# AdaWorldAPI stack: bevy (already on 1.95 for edition 2024) and
+# lance-graph (bumped in parallel). 1.95 introduced one new clippy lint
+# that fires on this codebase (`clippy::manual_checked_ops` on
+# `impl_owned_array.rs::into_scalar`); that's fixed in this same commit.
+# Never auto-track `stable` — bump explicitly when a future version is
+# reviewed and the workspace clippy passes clean.
 components = ["clippy", "rustfmt"]

src/impl_owned_array.rs

@@ -45,7 +45,12 @@ impl<A> Array<A, Ix0> {
             // by `array![1, 2, 3, 4].slice_move(s![2])`.)
             let first = self.parts.ptr.as_ptr() as usize;
             let base = self.data.as_ptr() as usize;
-            let index = (first - base) / size;
+            // Use `checked_div` to satisfy `clippy::manual_checked_ops`
+            // (new lint in Rust 1.95). The `size == 0` branch above already
+            // covers the divisor-is-zero case, so the `unwrap_or` is
+            // unreachable in practice — `0` is the safest fallback if some
+            // future refactor lets a `size == 0` ZST sneak past the guard.
+            let index = (first - base).checked_div(size).unwrap_or(0);
             debug_assert_eq!((first - base) % size, 0);
             // Remove the element at the index and return it.
             self.data.into_vec().remove(index)