From dff412d54d439a0f6ed52f7f3c19c42259edf341 Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Wed, 8 Jul 2026 14:08:19 -0700
Subject: [PATCH 1/9] Add macOS nightly build support via Swiftly

Adds a new opt-in macos-swiftly-build job that pairs an Xcode version
with a Swiftly-managed Swift toolchain (defaulting to main-snapshot),
since xcrun cannot see toolchains that Swiftly selects on PATH.
---
 .github/workflows/pull_request.yml       |  4 ++
 .github/workflows/swift_package_test.yml | 52 ++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 8da9c703..cd6a5c35 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -79,6 +79,10 @@ jobs:
       macos_build_command: |
         cd tests/TestPackage
         xcrun swift build
+      enable_macos_swiftly_checks: true
+      macos_swiftly_build_command: |
+        cd tests/TestPackage
+        swift build
 
   build_tests_ios:
     name: Build iOS Tests
diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index d5ee72d1..c73ca91f 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -22,6 +22,10 @@ on:
         type: string
         description: "macOS arch list (JSON)"
         default: "[\"ARM64\"]"
+      macos_swiftly_toolchains:
+        type: string
+        description: "List of macOS Swiftly toolchain builds to test, each pairing an Xcode version with a Swiftly-managed Swift toolchain (JSON list of objects with xcode_version, swift_version, os_version, arch)"
+        default: "[{\"xcode_version\": \"26.4\", \"swift_version\": \"main-snapshot\", \"os_version\": \"tahoe\", \"arch\": \"ARM64\"}]"
       ios_host_xcode_versions:
         type: string
         description: "Xcode version list (JSON)"
@@ -139,6 +143,10 @@ on:
         type: string
         description: "macOS command to build and test the package"
         default: "xcrun swift test"
+      macos_swiftly_build_command:
+        type: string
+        description: "macOS command to build and test the package when using a Swiftly-managed toolchain (run via `swiftly run`, so it should not use `xcrun`)"
+        default: "swift test"
       macos_build_timeout:
         type: number
         description: "The default step timeout in minutes"
@@ -245,6 +253,10 @@ on:
         type: boolean
         description: "Boolean to enable macOS testing. Defaults to false"
         default: false
+      enable_macos_swiftly_checks:
+        type: boolean
+        description: "Boolean to enable macOS testing with Swiftly-managed toolchains (e.g. nightly snapshots). Defaults to false"
+        default: false
       enable_ios_checks:
         type: boolean
         description: "Boolean to enable iOS testing. Defaults to false"
@@ -313,6 +325,46 @@ jobs:
         run: ${{ inputs.macos_build_command }} ${{ (contains(matrix.swift_version, 'nightly') && inputs.swift_nightly_flags) || inputs.swift_flags }}
         timeout-minutes: ${{ inputs.macos_build_timeout }}
 
+  macos-swiftly-build:
+    name: macOS via Swiftly (Xcode ${{ matrix.xcode_version }} + ${{ matrix.swift_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})
+    if: ${{ inputs.enable_macos_swiftly_checks }}
+    runs-on: [self-hosted, macos, "${{ matrix.os_version }}", "${{ matrix.arch }}"]
+    strategy:
+      fail-fast: false
+      matrix:
+        include: ${{ fromJson(inputs.macos_swiftly_toolchains) }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+      - name: Provide token
+        if: ${{ inputs.needs_token }}
+        run: |
+            echo "GITHUB_TOKEN=${{ secrets.GITHUB_TOKEN }}" >> $GITHUB_ENV
+      - name: Set environment variables
+        if: ${{ inputs.macos_env_vars }}
+        env:
+          ENV_VARS: ${{ inputs.macos_env_vars }}
+        run: |
+            for i in "${ENV_VARS}"
+            do
+              printf "%s\n" $i >> $GITHUB_ENV
+            done
+      - name: Select Xcode
+        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app" >> $GITHUB_ENV
+      - name: Install Swift toolchain via Swiftly
+        run: |
+          swiftly install ${{ matrix.swift_version }}
+          swiftly use ${{ matrix.swift_version }}
+      - name: Swift version
+        run: swiftly run swift --version
+      - name: Pre-build
+        # zizmor: ignore[template-injection]
+        run: ${{ inputs.macos_pre_build_command }}
+      - name: Build / Test
+        # zizmor: ignore[template-injection]
+        run: swiftly run ${{ inputs.macos_swiftly_build_command }} ${{ (contains(matrix.swift_version, 'snapshot') && inputs.swift_nightly_flags) || inputs.swift_flags }}
+        timeout-minutes: ${{ inputs.macos_build_timeout }}
+
   ios-build:
     name: iOS (Build Only, Xcode ${{ matrix.xcode_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})
     if: ${{ inputs.enable_ios_checks }}

From 59d3eefce98104769c8a82705f94499330be5861 Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Wed, 8 Jul 2026 14:22:47 -0700
Subject: [PATCH 2/9] Install Swiftly on self-hosted macOS runners before
 installing nightly toolchains

---
 .github/workflows/swift_package_test.yml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index c73ca91f..4e77bce3 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -351,6 +351,14 @@ jobs:
             done
       - name: Select Xcode
         run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app" >> $GITHUB_ENV
+      - name: Install Swiftly
+        run: |
+          curl -O https://download.swift.org/swiftly/darwin/swiftly.pkg
+          installer -pkg swiftly.pkg -target CurrentUserHomeDirectory
+          ~/.swiftly/bin/swiftly init --quiet-shell-followup
+          . "${SWIFTLY_HOME_DIR:-$HOME/.swiftly}/env.sh"
+          hash -r
+          echo "${SWIFTLY_HOME_DIR:-$HOME/.swiftly}/bin" >> $GITHUB_PATH
       - name: Install Swift toolchain via Swiftly
         run: |
           swiftly install ${{ matrix.swift_version }}

From 3ec076c7ba1eaa9b57529dc7ba7c7b1d617ec097 Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Wed, 8 Jul 2026 15:41:07 -0700
Subject: [PATCH 3/9] Add flags to swiftly

---
 .github/workflows/swift_package_test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index 4e77bce3..5ce367b2 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -355,7 +355,7 @@ jobs:
         run: |
           curl -O https://download.swift.org/swiftly/darwin/swiftly.pkg
           installer -pkg swiftly.pkg -target CurrentUserHomeDirectory
-          ~/.swiftly/bin/swiftly init --quiet-shell-followup
+          ~/.swiftly/bin/swiftly init --quiet-shell-followup --assume-yes --skip-install
           . "${SWIFTLY_HOME_DIR:-$HOME/.swiftly}/env.sh"
           hash -r
           echo "${SWIFTLY_HOME_DIR:-$HOME/.swiftly}/bin" >> $GITHUB_PATH

From a63197c97ef02df026dd3c80446ff0349f060c71 Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Thu, 9 Jul 2026 00:38:41 -0700
Subject: [PATCH 4/9] Use pre-installed Swiftly on self-hosted macOS runners
 instead of installing it

---
 .github/workflows/swift_package_test.yml | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index 5ce367b2..6125e647 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -351,14 +351,8 @@ jobs:
             done
       - name: Select Xcode
         run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app" >> $GITHUB_ENV
-      - name: Install Swiftly
-        run: |
-          curl -O https://download.swift.org/swiftly/darwin/swiftly.pkg
-          installer -pkg swiftly.pkg -target CurrentUserHomeDirectory
-          ~/.swiftly/bin/swiftly init --quiet-shell-followup --assume-yes --skip-install
-          . "${SWIFTLY_HOME_DIR:-$HOME/.swiftly}/env.sh"
-          hash -r
-          echo "${SWIFTLY_HOME_DIR:-$HOME/.swiftly}/bin" >> $GITHUB_PATH
+      - name: Add Swiftly to PATH
+        run: echo "$HOME/.swiftly/bin" >> $GITHUB_PATH
       - name: Install Swift toolchain via Swiftly
         run: |
           swiftly install ${{ matrix.swift_version }}

From 543d8ced563afb13c8d72287e6605159c000c277 Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Thu, 9 Jul 2026 00:46:24 -0700
Subject: [PATCH 5/9] Source Swiftly env.sh to set up environment for
 self-hosted macOS runners

---
 .github/workflows/swift_package_test.yml | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index 6125e647..45ea3531 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -351,8 +351,13 @@ jobs:
             done
       - name: Select Xcode
         run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app" >> $GITHUB_ENV
-      - name: Add Swiftly to PATH
-        run: echo "$HOME/.swiftly/bin" >> $GITHUB_PATH
+      - name: Set up Swiftly environment
+        run: |
+          . "$HOME/.swiftly/env.sh"
+          echo "SWIFTLY_HOME_DIR=$SWIFTLY_HOME_DIR" >> $GITHUB_ENV
+          echo "SWIFTLY_BIN_DIR=$SWIFTLY_BIN_DIR" >> $GITHUB_ENV
+          echo "SWIFTLY_TOOLCHAINS_DIR=$SWIFTLY_TOOLCHAINS_DIR" >> $GITHUB_ENV
+          echo "$SWIFTLY_BIN_DIR" >> $GITHUB_PATH
       - name: Install Swift toolchain via Swiftly
         run: |
           swiftly install ${{ matrix.swift_version }}

From d903953ed056d11f29a3174b95f6b9570f208cd4 Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Thu, 9 Jul 2026 01:32:03 -0700
Subject: [PATCH 6/9] Update swift_package_test.yml

---
 .github/workflows/swift_package_test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index 45ea3531..0d832916 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -369,7 +369,7 @@ jobs:
         run: ${{ inputs.macos_pre_build_command }}
       - name: Build / Test
         # zizmor: ignore[template-injection]
-        run: swiftly run ${{ inputs.macos_swiftly_build_command }} ${{ (contains(matrix.swift_version, 'snapshot') && inputs.swift_nightly_flags) || inputs.swift_flags }}
+        run: ${{ inputs.macos_swiftly_build_command }} ${{ (contains(matrix.swift_version, 'snapshot') && inputs.swift_nightly_flags) || inputs.swift_flags }}
         timeout-minutes: ${{ inputs.macos_build_timeout }}
 
   ios-build:

From 35fae1b3dbd5fa9e9d249293c2570c059d4eb39c Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Thu, 9 Jul 2026 01:33:48 -0700
Subject: [PATCH 7/9] Update pull_request.yml to use swiftly run

---
 .github/workflows/pull_request.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index cd6a5c35..6262e3e0 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -82,7 +82,7 @@ jobs:
       enable_macos_swiftly_checks: true
       macos_swiftly_build_command: |
         cd tests/TestPackage
-        swift build
+        swiftly run swift build
 
   build_tests_ios:
     name: Build iOS Tests

From 57a76abbbacbf730d353e4ad14e3740b94765794 Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Thu, 9 Jul 2026 10:55:26 -0700
Subject: [PATCH 8/9] Include /Contents/Developer when setting DEVELOPER_DIR

---
 .github/workflows/swift_package_test.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index 0d832916..d159242a 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -312,7 +312,7 @@ jobs:
               printf "%s\n" $i >> $GITHUB_ENV
             done
       - name: Select Xcode
-        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app" >> $GITHUB_ENV
+        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app/Contents/Developer" >> $GITHUB_ENV
       - name: Swift version
         run: xcrun swift --version
       - name: Clang version
@@ -350,7 +350,7 @@ jobs:
               printf "%s\n" $i >> $GITHUB_ENV
             done
       - name: Select Xcode
-        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app" >> $GITHUB_ENV
+        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app/Contents/Developer" >> $GITHUB_ENV
       - name: Set up Swiftly environment
         run: |
           . "$HOME/.swiftly/env.sh"
@@ -401,7 +401,7 @@ jobs:
               printf "%s\n" $i >> $GITHUB_ENV
             done
       - name: Select Xcode
-        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app" >> $GITHUB_ENV
+        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app/Contents/Developer" >> $GITHUB_ENV
       - name: Swift version
         run: |
           "$(xcrun -f swift)" --version

From 2571fd218271386b43d535e7aade6e6e1968dbdd Mon Sep 17 00:00:00 2001
From: Mishal Shah <mishal_shah@apple.com>
Date: Thu, 9 Jul 2026 12:21:39 -0700
Subject: [PATCH 9/9] Update swift_package_test.yml to use `swiftly run`

---
 .github/workflows/swift_package_test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index d159242a..950b6c0c 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -146,7 +146,7 @@ on:
       macos_swiftly_build_command:
         type: string
         description: "macOS command to build and test the package when using a Swiftly-managed toolchain (run via `swiftly run`, so it should not use `xcrun`)"
-        default: "swift test"
+        default: "swiftly run swift test"
       macos_build_timeout:
         type: number
         description: "The default step timeout in minutes"