lancedb: fix riscv64 SIMD-fallback patches for 0.38.0/0.39.0

CI failed applying patches/lancedb/<version>/0001*.patch for the two new
pending versions: no patch directory existed for them yet (only 0.37.1
had one), so the glob matched nothing and `git apply` errored on a
literal, missing filename.

lancedb pins lance-core/lance-linalg to a different exact version per
release (10.0.0 for v0.37.1, 11.0.0 for v0.38.0, 12.0.0 for v0.39.0),
but the workflow hardcoded checking out lance v10.0.0 for the riscv64
SIMD fallback regardless of which lancedb version was being built. Make
that checkout track whatever lance-core version the checked-out
lancedb's own Cargo.toml pins, and add the corresponding per-version
patch directories:

- 0001 (Cargo.toml `[patch.crates-io]` redirect) is unchanged across
  lance versions, copied verbatim from 0.37.1.
- 0002 (portable riscv64 SIMD fallback for lance-linalg's f32x8/f32x16/
  i32x8/f64x4/f64x8) reuses patches/pylance/11.0.0's fallback patch,
  which applies cleanly to both lance v11.0.0 (0.38.0) and v12.0.0
  (0.39.0) unchanged (verified locally with `git apply --check` against
  real lancedb/lance checkouts at both tags).

Author: luhenry

.github/workflows/build-lancedb.yml

@@ -77,16 +77,23 @@ jobs:
       - name: Apply lancedb patches
         run: git apply -v python-wheels/patches/lancedb/${{ env.LANCEDB_VERSION }}/0001*.patch
 
+      # lancedb pins lance-core/lance-linalg to a different exact version per
+      # release (10.0.0 for v0.37.1, 11.0.0 for v0.38.0, 12.0.0 for v0.39.0),
+      # so the sibling checkout below must track whatever this lancedb tag's
+      # own Cargo.toml pins rather than a fixed tag.
+      - name: Determine the lance-core/lance-linalg version lancedb pins
+        run: echo "LANCE_VERSION=$(grep -m1 '^lance-core = ' Cargo.toml | grep -oE '[0-9]+\.[0-9]+\.[0-9]+')" >> "$GITHUB_ENV"
+
       # lance-core's SIMD_SUPPORT static and lance-linalg's f32x8/f32x16/
       # i32x8/f64x4/f64x8 SIMD types compile only for x86_64/aarch64/
       # loongarch64 upstream; the 0002 patch adds a portable riscv64 fallback
       # to this checkout, and Cargo.toml's `[patch.crates-io]` (0001) redirects
       # both crates here.
-      - name: Checkout lance v10.0.0 and add a riscv64 SIMD fallback
+      - name: Checkout lance v${{ env.LANCE_VERSION }} and add a riscv64 SIMD fallback
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
         with:
           repository: lancedb/lance
-          ref: v10.0.0
+          ref: v${{ env.LANCE_VERSION }}
           path: lance
           persist-credentials: false
 

patches/lancedb/0.38.0/0001-cargo-redirect-lance-core-lance-linalg-to-a-riscv64.patch

@@ -0,0 +1,64 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Thu, 03 Sep 2026 00:00:00 +0000
+Subject: [PATCH] cargo: redirect lance-core/lance-linalg to a riscv64-patched
+ checkout
+
+lance-core's SIMD_SUPPORT static (rust/lance-core/src/utils/cpu.rs) and
+lance-linalg's f32x8/f32x16/i32x8/f64x4/f64x8 SIMD types
+(rust/lance-linalg/src/simd/{f32,i32,f64}.rs) are compiled for
+x86_64/aarch64/loongarch64 only, with no fallback arm for any other
+architecture: the SIMD_SUPPORT closure has no trailing expression on
+riscv64 ("expected SimdSupport, found ()"), and the SIMD type structs are
+defined only under those three `#[cfg(target_arch = ...)]` attributes
+while every method implementing them is unconditional, so riscv64 hits
+"cannot find type `f32x8` in this scope" as soon as lance-linalg is
+built.
+
+Both crates are pulled in from crates.io at a pinned `=10.0.0`, so the
+fix cannot be applied in place. Redirect them to a checkout of the same
+v10.0.0 tag carrying a portable scalar fallback for both, see
+0002-lance-linalg-add-a-portable-riscv64-simd-fallback.patch. `exclude`
+keeps that checkout's own [workspace] from being silently absorbed into
+this one, which would drop its `[workspace.package]` inheritance
+(version, edition, ...) for lance-core and lance-linalg.
+
+Only the source line of the lance-core/lance-linalg entries changes in
+Cargo.lock, so every other dependency stays pinned exactly as upstream
+released it.
+
+Upstream-Status: Inappropriate [redirects two pinned dependencies to a local checkout; the fix itself belongs in lancedb/lance]
+
+Signed-off-by: Ludovic Henry <git@ludovic.dev>
+---
+ Cargo.toml | 12 ++++++++++++
+ 1 file changed, 12 insertions(+)
+
+diff --git a/Cargo.toml b/Cargo.toml
+index a47e59e..ab6cf5c 100644
+--- a/Cargo.toml
++++ b/Cargo.toml
+@@ -1,5 +1,10 @@
+ [workspace]
+ members = ["rust/lancedb", "nodejs", "python"]
++# ./lance (see [patch.crates-io] below) carries its own [workspace]; excluding
++# it keeps that workspace independent instead of being silently absorbed into
++# this one, which would drop its `[workspace.package]` inheritance (version,
++# edition, ...) for lance-core and lance-linalg.
++exclude = ["lance"]
+ resolver = "2"
+ 
+ [workspace.package]
+@@ -80,3 +85,10 @@ debug = false
+ debug-assertions = false
+ strip = "debuginfo"
+ incremental = false
++
++# lance-core's SIMD_SUPPORT and lance-linalg's f32x8/f32x16/i32x8/f64x4/f64x8
++# SIMD types compile only for x86_64/aarch64/loongarch64 upstream; ./lance is
++# the same v10.0.0 tag with a riscv64 scalar fallback added to both.
++[patch.crates-io]
++lance-core = { path = "lance/rust/lance-core" }
++lance-linalg = { path = "lance/rust/lance-linalg" }
+-- 
+2.43.0