diff --git a/.github/sync-packages.php b/.github/sync-packages.php
new file mode 100644
index 000000000..e5bf79cfe
--- /dev/null
+++ b/.github/sync-packages.php
@@ -0,0 +1,71 @@
+<?php
+
+if ('cli' !== PHP_SAPI) {
+    echo "This script can only be run from the command line.\n";
+    exit(1);
+}
+
+$mainRepo = 'https://github.com/symfony/polyfill';
+exec('find src/ -name composer.json -not -path "src/Xml/*"', $packages);
+
+foreach ($packages as $package) {
+    $package = dirname($package);
+    $c = file_get_contents($package.'/.gitattributes');
+    $c = preg_replace('{^/\.git.*+\n}m', '', $c);
+    $c .= "/.git* export-ignore\n";
+    file_put_contents($package.'/.gitattributes', $c);
+
+
+    @mkdir($package.'/.github');
+    file_put_contents($package.'/.github/PULL_REQUEST_TEMPLATE.md', <<<EOTXT
+        Please do not submit any Pull Requests here. They will be closed.
+        ---
+
+        Please submit your PR here instead:
+        {$mainRepo}
+
+        This repository is what we call a "subtree split": a read-only subset of that main repository.
+        We're looking forward to your PR there!
+
+        EOTXT
+    );
+
+    @mkdir($package.'/.github/workflows');
+    file_put_contents($package.'/.github/workflows/check-subtree-split.yml', <<<EOTXT
+        name: Check subtree split
+        on:
+          pull_request_target:
+        jobs:
+          close-pull-request:
+            runs-on: ubuntu-latest
+            steps:
+            - name: Close pull request
+              uses: actions/github-script@v6
+              with:
+                script: |
+                  if (context.repo.owner === "symfony") {
+                    github.rest.issues.createComment({
+                      owner: "symfony",
+                      repo: context.repo.repo,
+                      issue_number: context.issue.number,
+                      body: `
+                  Thanks for your Pull Request! We love contributions.
+
+                  However, you should instead open your PR on the main repository:
+                  {$mainRepo}
+
+                  This repository is what we call a "subtree split": a read-only subset of that main repository.
+                  We're looking forward to your PR there!
+                  `
+                    });
+                    github.rest.pulls.update({
+                      owner: "symfony",
+                      repo: context.repo.repo,
+                      pull_number: context.issue.number,
+                      state: "closed"
+                    });
+                  }
+
+        EOTXT
+    );
+}
diff --git a/.github/workflows/package-tests.yml b/.github/workflows/package-tests.yml
new file mode 100644
index 000000000..2581e686b
--- /dev/null
+++ b/.github/workflows/package-tests.yml
@@ -0,0 +1,26 @@
+name: Verify Packages
+
+on:
+  pull_request:
+    paths:
+      - src/**
+
+permissions:
+  contents: read
+
+jobs:
+  verify:
+    name: Verify Packages
+    runs-on: Ubuntu-20.04
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Fetch branch from where the PR started
+        run: git fetch --no-tags --prune --depth=1 origin +refs/heads/*:refs/remotes/origin/*
+
+      - name: Verify subtree-splits are auto-closed
+        run: |
+          php .github/sync-packages.php
+          git add src/
+          git diff --staged --exit-code || (echo '::error::Please run "php .github/sync-packages.php".' && exit 1)
diff --git a/src/Apcu/.gitattributes b/src/Apcu/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Apcu/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Apcu/.github/PULL_REQUEST_TEMPLATE.md b/src/Apcu/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Apcu/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Apcu/.github/workflows/check-subtree-split.yml b/src/Apcu/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Apcu/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Ctype/.gitattributes b/src/Ctype/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Ctype/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Ctype/.github/PULL_REQUEST_TEMPLATE.md b/src/Ctype/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Ctype/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Ctype/.github/workflows/check-subtree-split.yml b/src/Ctype/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Ctype/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Iconv/.gitattributes b/src/Iconv/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Iconv/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Iconv/.github/PULL_REQUEST_TEMPLATE.md b/src/Iconv/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Iconv/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Iconv/.github/workflows/check-subtree-split.yml b/src/Iconv/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Iconv/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Intl/Grapheme/.gitattributes b/src/Intl/Grapheme/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Intl/Grapheme/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Intl/Grapheme/.github/PULL_REQUEST_TEMPLATE.md b/src/Intl/Grapheme/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Intl/Grapheme/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Intl/Grapheme/.github/workflows/check-subtree-split.yml b/src/Intl/Grapheme/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Intl/Grapheme/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Intl/Icu/.gitattributes b/src/Intl/Icu/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Intl/Icu/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Intl/Icu/.github/PULL_REQUEST_TEMPLATE.md b/src/Intl/Icu/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Intl/Icu/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Intl/Icu/.github/workflows/check-subtree-split.yml b/src/Intl/Icu/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Intl/Icu/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Intl/Idn/.gitattributes b/src/Intl/Idn/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Intl/Idn/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Intl/Idn/.github/PULL_REQUEST_TEMPLATE.md b/src/Intl/Idn/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Intl/Idn/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Intl/Idn/.github/workflows/check-subtree-split.yml b/src/Intl/Idn/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Intl/Idn/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Intl/MessageFormatter/.gitattributes b/src/Intl/MessageFormatter/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Intl/MessageFormatter/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Intl/MessageFormatter/.github/PULL_REQUEST_TEMPLATE.md b/src/Intl/MessageFormatter/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Intl/MessageFormatter/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Intl/MessageFormatter/.github/workflows/check-subtree-split.yml b/src/Intl/MessageFormatter/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Intl/MessageFormatter/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Intl/Normalizer/.gitattributes b/src/Intl/Normalizer/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Intl/Normalizer/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Intl/Normalizer/.github/PULL_REQUEST_TEMPLATE.md b/src/Intl/Normalizer/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Intl/Normalizer/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Intl/Normalizer/.github/workflows/check-subtree-split.yml b/src/Intl/Normalizer/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Intl/Normalizer/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Mbstring/.gitattributes b/src/Mbstring/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Mbstring/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Mbstring/.github/PULL_REQUEST_TEMPLATE.md b/src/Mbstring/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Mbstring/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Mbstring/.github/workflows/check-subtree-split.yml b/src/Mbstring/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Mbstring/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php72/.gitattributes b/src/Php72/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php72/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php72/.github/PULL_REQUEST_TEMPLATE.md b/src/Php72/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php72/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php72/.github/workflows/check-subtree-split.yml b/src/Php72/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php72/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php73/.gitattributes b/src/Php73/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php73/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php73/.github/PULL_REQUEST_TEMPLATE.md b/src/Php73/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php73/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php73/.github/workflows/check-subtree-split.yml b/src/Php73/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php73/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php74/.gitattributes b/src/Php74/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php74/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php74/.github/PULL_REQUEST_TEMPLATE.md b/src/Php74/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php74/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php74/.github/workflows/check-subtree-split.yml b/src/Php74/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php74/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php80/.gitattributes b/src/Php80/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php80/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php80/.github/PULL_REQUEST_TEMPLATE.md b/src/Php80/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php80/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php80/.github/workflows/check-subtree-split.yml b/src/Php80/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php80/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php81/.gitattributes b/src/Php81/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php81/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php81/.github/PULL_REQUEST_TEMPLATE.md b/src/Php81/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php81/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php81/.github/workflows/check-subtree-split.yml b/src/Php81/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php81/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php82/.gitattributes b/src/Php82/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php82/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php82/.github/PULL_REQUEST_TEMPLATE.md b/src/Php82/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php82/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php82/.github/workflows/check-subtree-split.yml b/src/Php82/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php82/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php83/.gitattributes b/src/Php83/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php83/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php83/.github/PULL_REQUEST_TEMPLATE.md b/src/Php83/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php83/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php83/.github/workflows/check-subtree-split.yml b/src/Php83/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php83/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Php84/.gitattributes b/src/Php84/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Php84/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Php84/.github/PULL_REQUEST_TEMPLATE.md b/src/Php84/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Php84/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Php84/.github/workflows/check-subtree-split.yml b/src/Php84/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Php84/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Util/.gitattributes b/src/Util/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Util/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Util/.github/PULL_REQUEST_TEMPLATE.md b/src/Util/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Util/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Util/.github/workflows/check-subtree-split.yml b/src/Util/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Util/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }
diff --git a/src/Uuid/.gitattributes b/src/Uuid/.gitattributes
new file mode 100644
index 000000000..825312826
--- /dev/null
+++ b/src/Uuid/.gitattributes
@@ -0,0 +1 @@
+/.git* export-ignore
diff --git a/src/Uuid/.github/PULL_REQUEST_TEMPLATE.md b/src/Uuid/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..1325301f8
--- /dev/null
+++ b/src/Uuid/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,8 @@
+Please do not submit any Pull Requests here. They will be closed.
+---
+
+Please submit your PR here instead:
+https://github.com/symfony/polyfill
+
+This repository is what we call a "subtree split": a read-only subset of that main repository.
+We're looking forward to your PR there!
diff --git a/src/Uuid/.github/workflows/check-subtree-split.yml b/src/Uuid/.github/workflows/check-subtree-split.yml
new file mode 100644
index 000000000..efc143261
--- /dev/null
+++ b/src/Uuid/.github/workflows/check-subtree-split.yml
@@ -0,0 +1,33 @@
+name: Check subtree split
+on:
+  pull_request_target:
+jobs:
+  close-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Close pull request
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if (context.repo.owner === "symfony") {
+            github.rest.issues.createComment({
+              owner: "symfony",
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `
+          Thanks for your Pull Request! We love contributions.
+
+          However, you should instead open your PR on the main repository:
+          https://github.com/symfony/polyfill
+
+          This repository is what we call a "subtree split": a read-only subset of that main repository.
+          We're looking forward to your PR there!
+          `
+            });
+            github.rest.pulls.update({
+              owner: "symfony",
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+              state: "closed"
+            });
+          }