From 751daf0b374775ade8ae32e40c7931006a0acac8 Mon Sep 17 00:00:00 2001
From: Jonathan Keane <jkeane@gmail.com>
Date: Fri, 13 Feb 2026 11:46:42 -0600
Subject: [PATCH 1/3] macos 11 sdk from jonkeane/crossbow

---
 dev/tasks/r/github.macos.cran.yml | 34 +++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/dev/tasks/r/github.macos.cran.yml b/dev/tasks/r/github.macos.cran.yml
index dda8ac7fd78..34841c9fb59 100644
--- a/dev/tasks/r/github.macos.cran.yml
+++ b/dev/tasks/r/github.macos.cran.yml
@@ -21,10 +21,12 @@
 
 jobs:
   macos-cran:
-    name: "macOS similar to CRAN"
+    name: "macOS {{ '${{ matrix.config }}' }}"
     runs-on: macOS-latest
     strategy:
       fail-fast: false
+      matrix:
+        config: ["cran-m1", "cran-release"]
 
     steps:
       {{ macros.github_checkout_arrow()|indent }}
@@ -58,7 +60,35 @@ jobs:
           extra-packages: |
             any::rcmdcheck
             any::sys
-      - name: Install
+      - name: Install MacOSX 11.3 SDK
+        if: matrix.config == 'cran-release'
+        env:
+          SDK_TOKEN: {{ '${{ secrets.JONKEANE_MACOS_11_SDK_DOWNLOAD_TOKEN }}' }}
+        run: |
+          # Download, Confirm integrity, expand. This will fail if the hash does not match.
+          curl -fsSL -H "Authorization: Bearer $SDK_TOKEN" \
+            -H "Accept: application/vnd.github+json" \
+            https://api.github.com/repos/jonkeane/crossbow_11_sdk/tarball/v0.0.1 \
+            -o /tmp/MacOSX11.3.sdk.tar.gz
+          echo "493570e56d6c6af26128e9096de738822589cc3cdb1b29aa5854f3f4c99756ac  /tmp/MacOSX11.3.sdk.tar.gz" | shasum -a 256 -c -
+          sudo tar -xzf /tmp/MacOSX11.3.sdk.tar.gz -C /Library/Developer/CommandLineTools/SDKs/
+          # Move SDK from extracted folder (GitHub archives as {owner}-{repo}-{sha}/)
+          sudo mv /Library/Developer/CommandLineTools/SDKs/jonkeane-crossbow_11_sdk-*/MacOSX11.3.sdk \
+            /Library/Developer/CommandLineTools/SDKs/MacOSX11.3.sdk
+          sudo rm -rf /Library/Developer/CommandLineTools/SDKs/jonkeane-crossbow_11_sdk-*
+          ls -la /Library/Developer/CommandLineTools/SDKs/
+      - name: Install (cran-release)
+        if: matrix.config == 'cran-release'
+        env:
+          _R_CHECK_CRAN_INCOMING_: false
+          SDKROOT: '/Library/Developer/CommandLineTools/SDKs/MacOSX11.3.sdk'
+          NOT_CRAN: false
+        run: |
+          sccache --start-server || echo 'sccache not found'
+          cd arrow/r
+          R CMD INSTALL . --install-tests
+      - name: Install (cran-m1)
+        if: matrix.config == 'cran-m1'
         env:
           _R_CHECK_CRAN_INCOMING_: false
           CXX: "clang++ -mmacos-version-min=14.6"

From 3cf3c711ef7e449500cf2fd23c3ac55908ad706c Mon Sep 17 00:00:00 2001
From: Jonathan Keane <jkeane@gmail.com>
Date: Tue, 10 Feb 2026 22:16:31 -0600
Subject: [PATCH 2/3] Workaround on older partially compliant C++20
 implementations

---
 cpp/src/arrow/compute/kernels/hash_aggregate.cc | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/cpp/src/arrow/compute/kernels/hash_aggregate.cc b/cpp/src/arrow/compute/kernels/hash_aggregate.cc
index ed50025ef5f..7f2ce123377 100644
--- a/cpp/src/arrow/compute/kernels/hash_aggregate.cc
+++ b/cpp/src/arrow/compute/kernels/hash_aggregate.cc
@@ -277,8 +277,15 @@ template <typename T>
 concept CBooleanConcept = std::same_as<T, bool>;
 
 // XXX: Ideally we want to have std::floating_point<Float16> = true.
+// Some older standard library implementations (e.g., macOS 11.x libc++) have partial
+// C++20 concepts support with std::same_as but lack std::floating_point.
+#if defined(__cpp_lib_concepts) && __cpp_lib_concepts >= 202002L
 template <typename T>
 concept CFloatingPointConcept = std::floating_point<T> || std::same_as<T, util::Float16>;
+#else
+template <typename T>
+concept CFloatingPointConcept = std::is_floating_point_v<T> || std::same_as<T, util::Float16>;
+#endif
 
 template <typename T>
 concept CDecimalConcept = std::same_as<T, Decimal32> || std::same_as<T, Decimal64> ||

From 08daa2e74dc9d2c652da3c3f248f641675b0d106 Mon Sep 17 00:00:00 2001
From: Jonathan Keane <jkeane@gmail.com>
Date: Fri, 13 Feb 2026 12:18:07 -0600
Subject: [PATCH 3/3] linting

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 cpp/src/arrow/compute/kernels/hash_aggregate.cc | 3 ++-
 dev/tasks/r/github.macos.cran.yml               | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/cpp/src/arrow/compute/kernels/hash_aggregate.cc b/cpp/src/arrow/compute/kernels/hash_aggregate.cc
index 7f2ce123377..3ab7ff065b2 100644
--- a/cpp/src/arrow/compute/kernels/hash_aggregate.cc
+++ b/cpp/src/arrow/compute/kernels/hash_aggregate.cc
@@ -284,7 +284,8 @@ template <typename T>
 concept CFloatingPointConcept = std::floating_point<T> || std::same_as<T, util::Float16>;
 #else
 template <typename T>
-concept CFloatingPointConcept = std::is_floating_point_v<T> || std::same_as<T, util::Float16>;
+concept CFloatingPointConcept =
+    std::is_floating_point_v<T> || std::same_as<T, util::Float16>;
 #endif
 
 template <typename T>
diff --git a/dev/tasks/r/github.macos.cran.yml b/dev/tasks/r/github.macos.cran.yml
index 34841c9fb59..930f7c5587e 100644
--- a/dev/tasks/r/github.macos.cran.yml
+++ b/dev/tasks/r/github.macos.cran.yml
@@ -107,6 +107,6 @@ jobs:
       - name: Save the test output
         uses: actions/upload-artifact@v4
         with:
-          name: test-output
+          name: test-output-{{ '${{ matrix.config }}' }}
           path: arrow-tests/testthat.Rout*
         if: always()