From 5a8f896515e3abe01f3023af28ffd34846e36da9 Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Thu, 19 Mar 2026 18:15:09 +0000
Subject: [PATCH 1/7] Backport and disable workflows from 5.4

---
 .gitattributes                               |   1 +
 .github/workflows/build-cross.yml            | 287 +++++++++++++++++++
 .github/workflows/build-msvc.yml             | 215 ++++++++++++++
 .github/workflows/hygiene.yml                |  14 -
 .github/workflows/multicoretests.yml         |  72 +++++
 .github/workflows/parsetree-change.yml       |  32 +++
 .github/workflows/tsan.yml                   | 102 +++++++
 tools/ci/actions/check-parsetree-modified.sh |  54 ----
 tools/ci/actions/multicoretests.sh           |  89 ++++++
 tools/ci/actions/runner.sh                   |  10 +
 10 files changed, 808 insertions(+), 68 deletions(-)
 create mode 100644 .github/workflows/build-cross.yml
 create mode 100644 .github/workflows/build-msvc.yml
 create mode 100644 .github/workflows/multicoretests.yml
 create mode 100644 .github/workflows/parsetree-change.yml
 create mode 100644 .github/workflows/tsan.yml
 delete mode 100755 tools/ci/actions/check-parsetree-modified.sh
 create mode 100755 tools/ci/actions/multicoretests.sh

diff --git a/.gitattributes b/.gitattributes
index f1a14e3689c8..c7d836021563 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -57,6 +57,7 @@ tools/mantis2gh_stripped.csv typo.missing-header
 
 # Github templates and scripts lack headers, have long lines
 /.github/**              typo.missing-header typo.long-line=may typo.very-long-line=may
+/.github/workflows/*.yml typo.non-ascii=may
 
 /.mailmap                typo.long-line typo.missing-header typo.non-ascii
 /.merlin                 typo.missing-header
diff --git a/.github/workflows/build-cross.yml b/.github/workflows/build-cross.yml
new file mode 100644
index 000000000000..950cfd005045
--- /dev/null
+++ b/.github/workflows/build-cross.yml
@@ -0,0 +1,287 @@
+name: Cross compilers
+
+on:
+  workflow_dispatch:
+
+# Restrict the GITHUB_TOKEN
+permissions: {}
+
+# See build.yml
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ github.event_name == 'pull_request' || github.sha }}
+  cancel-in-progress: true
+
+env:
+  failed: 0
+  TESTDIR: >-
+    C:\Бактріан🐫
+  STR_UTF8: >-
+    "C:\\Бактріан🐫"
+  STR_UTF16: >-
+    L"C:\\\x0411\x0430\x043a\x0442\x0440\x0456\x0430\x043d\xd83d\xdc2b"
+  EXAMPLE_PROGRAM: |
+    let _ =
+      Printf.printf "Version: %s\nOS: %s\nUnix: %b\nWin: %b\nCygwin: %b\n"
+        Sys.ocaml_version Sys.os_type Sys.unix Sys.win32 Sys.cygwin
+  COMPLIBS_PROG_X86_64: |
+    let _ =
+      Printf.printf "allow_unaligned_access = %b\n" Arch.allow_unaligned_access;
+      Printf.printf "win64 = %b\n" Arch.win64
+  COMPLIBS_PROG_AARCH64: |
+    let _ =
+      Printf.printf "allow_unaligned_access = %b\n" Arch.allow_unaligned_access;
+      Printf.printf "macosx = %b\n" Arch.macosx
+
+jobs:
+  non-cross:
+    if: contains(github.event.pull_request.labels.*.name, 'run-crosscompiler-tests')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout OCaml
+        uses: actions/checkout@v5
+        with:
+          persist-credentials: false
+      - name: Configure, build and install OCaml
+        run: |
+          PREFIX="$HOME/.local"
+          echo "$PREFIX/bin" >> "$GITHUB_PATH"
+          set -x
+          ./configure --disable-warn-error --disable-ocamldoc \
+              --disable-ocamltest --disable-stdlib-manpages \
+              --disable-dependency-generation --prefix="$PREFIX" || failed=$?
+          if ((failed)) ; then set +x
+            echo ; echo "::group::config.log content ($(wc -l config.log) lines)"
+            cat config.log ; echo '::endgroup::' ; exit $failed
+          fi
+          make -j
+          make install
+          cd "$HOME"
+          tar caf /tmp/ocaml.tar.zst .local
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: non-cross-ocaml
+          path: /tmp/ocaml.tar.zst
+          retention-days: 1
+
+  cross-windows:
+    runs-on: ubuntu-latest
+    needs: non-cross
+    steps:
+      - name: Download Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: non-cross-ocaml
+      - name: Install non-cross OCaml and set up environment
+        run: |
+          set -x
+          tar xaf ocaml.tar.zst -C "$HOME"
+          rm -f ocaml.tar.zst
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+          sudo apt-get update -y
+          sudo apt-get install -y gcc-mingw-w64-x86-64
+      - name: Checkout OCaml
+        uses: actions/checkout@v5
+        with:
+          submodules: true
+          persist-credentials: false
+      - name: Configure, build and install Linux-to-Windows OCaml
+        run: |
+          set -x
+          ./configure --prefix="$HOME/cross" --target=x86_64-w64-mingw32 \
+              TARGET_LIBDIR="$TESTDIR" || failed=$?
+          if ((failed)) ; then set +x
+            echo ; echo "::group::config.log content ($(wc -l config.log) lines)"
+            cat config.log ; echo '::endgroup::' ; exit $failed
+          fi
+          # The OOM-killer may be triggered if the number of parallel
+          # jobs isn't limited.
+          make crossopt -j$(nproc)
+          make installcross
+          ln -sr "$HOME/cross/bin/flexlink.opt.exe" "$HOME/.local/bin/flexlink"
+      - name: Show opt.opt configuration
+        run: |
+          set -x
+          $HOME/cross/bin/ocamlopt.opt.exe -config
+          cat runtime/build_config.h
+      - name: Cross compile a small program
+        run: |
+          printf %s "$EXAMPLE_PROGRAM$COMPLIBS_PROG_X86_64" > example.ml
+          set -x
+          cat example.ml
+          $HOME/cross/bin/ocamlopt.opt.exe -I $HOME/cross/lib/ocaml/compiler-libs/ ocamlcommon.cmxa ocamloptcomp.cmxa example.ml -o example.exe -verbose
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: windows-executable
+          path: example.exe
+          retention-days: 1
+      - name: Test cross sak
+        run: |
+          printf %s "$STR_UTF16" > utf16.ref
+          printf %s "$STR_UTF8" > utf8.ref
+          set -x
+          runtime/sak encode-C-utf16-literal "$TESTDIR" > utf16
+          git diff --no-index utf16.ref utf16
+          runtime/sak encode-C-utf8-literal "$TESTDIR" > utf8
+          git diff --no-index utf8.ref utf8
+
+  run-windows:
+    runs-on: windows-latest
+    needs: cross-windows
+    steps:
+      - name: Download Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: windows-executable
+      - name: Run example program
+        run: |
+          .\example.exe
+
+  cross-arm-linux:
+    runs-on: ubuntu-latest
+    needs: non-cross
+    steps:
+      - name: Download Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: non-cross-ocaml
+      - name: Install non-cross OCaml and set up environment
+        run: |
+          set -x
+          tar xaf ocaml.tar.zst -C "$HOME"
+          rm -f ocaml.tar.zst
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+          sudo apt-get update -y
+          sudo apt-get install -y gcc-aarch64-linux-gnu qemu-user
+      - name: Checkout OCaml
+        uses: actions/checkout@v5
+        with:
+          submodules: true
+          persist-credentials: false
+      - name: Configure, build and install Linux-to-Windows OCaml
+        run: |
+          set -x
+          ./configure --prefix="$HOME/cross" --target=aarch64-linux-gnu \
+              || failed=$?
+          if ((failed)) ; then set +x
+            echo ; echo "::group::config.log content ($(wc -l config.log) lines)"
+            cat config.log ; echo '::endgroup::' ; exit $failed
+          fi
+          make crossopt -j
+          make installcross
+      - name: Show opt.opt configuration
+        run: |
+          set -x
+          $HOME/cross/bin/ocamlopt.opt -config
+          cat runtime/build_config.h
+      - name: Cross compile a small program
+        run: |
+          printf %s "$EXAMPLE_PROGRAM$COMPLIBS_PROG_AARCH64" > example.ml
+          set -x
+          cat example.ml
+          $HOME/cross/bin/ocamlopt.opt -I $HOME/cross/lib/ocaml/compiler-libs/ ocamlcommon.cmxa ocamloptcomp.cmxa example.ml -o example -verbose
+      - name: Run the small example program
+        run: |
+          set -x
+          qemu-aarch64 -L /usr/aarch64-linux-gnu example
+      - name: Test cross sak
+        run: |
+          printf %s "$STR_UTF16" > utf16.ref
+          printf %s "$STR_UTF8" > utf8.ref
+          set -x
+          runtime/sak encode-C-utf16-literal "$TESTDIR" > utf16
+          git diff --no-index utf16.ref utf16
+          runtime/sak encode-C-utf8-literal "$TESTDIR" > utf8
+          git diff --no-index utf8.ref utf8
+
+  cross-android:
+    runs-on: ubuntu-latest
+    needs: non-cross
+    env:
+      # https://developer.android.com/ndk/downloads#lts-downloads
+      NDK: r27d # Latest LTS Version
+      API_LEVEL: 21
+    steps:
+      - name: Download Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: non-cross-ocaml
+      - name: Install non-cross OCaml
+        run: |
+          set -x
+          tar xaf ocaml.tar.zst -C "$HOME"
+          rm -f ocaml.tar.zst
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+      - name: Restore the Android NDK from cache
+        uses: actions/cache/restore@v4
+        id: cache
+        with:
+          path: |
+            /home/runner/android
+          key: android-ndk-${{ env.NDK }}
+      - name: Download the Android NDK
+        run: |
+          set -x
+          mkdir -p "$HOME/android"
+          cd "$HOME/android"
+          wget --no-verbose "https://dl.google.com/android/repository/android-ndk-$NDK-linux.zip"
+          unzip android-ndk-$NDK-linux.zip
+          rm android-ndk-$NDK-linux.zip
+        if: steps.cache.outputs.cache-hit != 'true'
+      - name: Save the Android NDK to cache
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            /home/runner/android
+          key: android-ndk-${{ env.NDK }}
+        if: steps.cache.outputs.cache-hit != 'true'
+      - name: Checkout OCaml
+        uses: actions/checkout@v5
+        with:
+          persist-credentials: false
+      - name: Configure, build and install Linux-to-Android OCaml
+        env:
+          TARGET: x86_64-linux-android${{ env.API_LEVEL }}
+          TOOLDIR: android-ndk-${{ env.NDK }}/toolchains/llvm/prebuilt/linux-x86_64/bin
+        run: |
+          DIR="$HOME/android/$TOOLDIR"
+          set -x
+          # Hack around the fact that pthread_cancel isn't available on Android
+          # So the result program should _not_ be run with cleanup on exit
+          # (so no `c=1` in `OCAMLRUNPARAM`)
+          ./configure --prefix="$HOME/cross" --target=$TARGET \
+              TARGET_LIBDIR="/dummy/directory" \
+              CC="$DIR/clang --target=$TARGET" \
+              CPPFLAGS='-Dpthread_cancel=assert' \
+              AR="$DIR/llvm-ar" \
+              PARTIALLD="$DIR/ld -r" \
+              RANLIB="$DIR/llvm-ranlib" \
+              STRIP="$DIR/llvm-strip" || failed=$?
+          if ((failed)) ; then set +x
+            echo ; echo "::group::config.log content ($(wc -l config.log) lines)"
+            cat config.log ; echo '::endgroup::' ; exit $failed
+          fi
+          make crossopt -j
+          make installcross
+      - name: Show opt.opt configuration
+        run: |
+          set -x
+          $HOME/cross/bin/ocamlopt.opt -config
+          cat runtime/build_config.h
+      - name: Cross compile a small program
+        run: |
+          printf %s "$EXAMPLE_PROGRAM" > example.ml
+          set -x
+          cat example.ml
+          $HOME/cross/bin/ocamlopt.opt example.ml -o example -verbose
+          file example
+      - name: Run example
+        uses: reactivecircus/android-emulator-runner@v2
+        with:
+          api-level: ${{ env.API_LEVEL }}
+          arch: x86_64
+          disable-animations: true
+          script: |
+            adb push example /data/local/tmp/example
+            adb shell /data/local/tmp/example
diff --git a/.github/workflows/build-msvc.yml b/.github/workflows/build-msvc.yml
new file mode 100644
index 000000000000..2331a9be79cc
--- /dev/null
+++ b/.github/workflows/build-msvc.yml
@@ -0,0 +1,215 @@
+name: Build with MSVC
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+on:
+  workflow_dispatch:
+
+# env:
+  # Fully print commands executed by Make
+  # MAKEFLAGS: V=1
+
+defaults:
+  run:
+    shell: bash -eo pipefail -o igncr {0}
+
+jobs:
+  config:
+    runs-on: ubuntu-latest
+    outputs:
+      full-matrix: ${{ steps.full.outputs.result }}
+      matrix: ${{ steps.matrix.outputs.result}}
+      skip-testsuite: ${{ steps.skip.outputs.result }}
+    steps:
+      - name: Record if the build matrix is expanded
+        id: full
+        uses: actions/github-script@v7
+        with:
+          script: |
+            let full_matrix = false;
+            if (context.payload.pull_request) {
+              const { data: labels } =
+                await github.rest.issues.listLabelsOnIssue({...context.repo, issue_number: context.payload.pull_request.number});
+              full_matrix = labels.some(label => label.name === 'CI: Full matrix');
+            }
+            console.log('Full matrix: ' + full_matrix);
+            return full_matrix;
+      - name: Compute matrix for the "build" job
+        id: matrix
+        uses: actions/github-script@v7
+        with:
+          script: |
+            // # Always test cl and clang-cl
+            let compilers = ['gcc'];
+            // # Also test i686 MSVC
+            let include = [];
+            // # If this is a pull request, see if the PR has the
+            // # 'CI: Full matrix' label. This is done using an API request,
+            // # rather than from context.payload.pull_request.labels, since we
+            // # want the _current_ list of labels. This allows the labelling to
+            // # be changed, and then forcing a re-run of the workflow, rather
+            // # than having labelling triggering a fresh workflow event (which
+            // # is wasteful).
+            if (context.payload.pull_request) {
+              const { data: labels } =
+                await github.rest.issues.listLabelsOnIssue({...context.repo, issue_number: context.payload.pull_request.number});
+              if (labels.some(label => label.name === 'CI: Full matrix')) {
+                console.log('Full matrix requested');
+                // # Test bytecode-only Cygwin
+                include.push({cc: 'gcc', arch: 'x86_64', config_arg: '--disable-native-compiler'});
+              }
+            }
+            return {config_arg: [''], arch: ['x86_64'], cc: compilers, include: include};
+      - name: Determine if the testsuite should be skipped
+        id: skip
+        uses: actions/github-script@v7
+        with:
+          script: |
+            let skip_testsuite = false;
+            if (context.payload.pull_request) {
+              const { data: labels } =
+                await github.rest.issues.listLabelsOnIssue({...context.repo, issue_number: context.payload.pull_request.number});
+              skip_testsuite = labels.some(label => label.name === 'CI: Skip testsuite');
+            }
+            console.log('Skip testsuite: ' + skip_testsuite);
+            return skip_testsuite;
+
+  build:
+    permissions: {}
+
+    runs-on: windows-latest
+
+    needs: config
+
+    timeout-minutes: ${{ matrix.cc == 'gcc' && 90 || 60 }}
+
+    name: ${{ matrix.cc == 'cl' && 'MSVC' || matrix.cc == 'gcc' && 'Cygwin' || 'clang-cl' }} ${{ matrix.arch }} ${{ matrix.config_arg != '' && format('({0})', matrix.config_arg) || '' }}
+
+    strategy:
+      matrix: ${{ fromJSON(needs.config.outputs.matrix) }}
+      fail-fast: true
+
+    steps:
+      - name: Set git to use Unix line-endings for the testsuite
+        run: |
+          git config --global core.autocrlf false
+          git config --global core.eol lf
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Fetch OCaml
+        uses: actions/checkout@v5
+        with:
+          submodules: true
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Restore Cygwin cache
+        uses: actions/cache/restore@v4
+        with:
+          path: |
+            C:\cygwin-packages
+          key: cygwin-packages
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Install Cygwin
+        uses: cygwin/cygwin-install-action@v3
+        with:
+          packages: make,${{ matrix.cc != 'gcc' && 'mingw64-x86_64-' || 'gcc-fortran,' }}gcc-core
+          install-dir: 'D:\cygwin'
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Save Cygwin cache
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            C:\cygwin-packages
+          key: cygwin-packages
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Set up MSVC
+        uses: ilammy/msvc-dev-cmd@v1
+        with:
+          arch: ${{ matrix.arch == 'x86_64' && 'x64' || 'x86' }}
+        if: matrix.cc != 'gcc'
+
+      - name: Compute a key to cache configure results
+        id: autoconf-cache-key
+        env:
+          HOST: ${{ format('{0}-pc-{1}', matrix.arch, (matrix.cc == 'gcc' && 'cygwin' || 'windows')) }}
+        run: |
+          echo "key=${{ env.HOST }}-${{ matrix.cc }}-${{ hashFiles('configure') }}" >> $GITHUB_OUTPUT
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Restore Autoconf cache
+        uses: actions/cache/restore@v4
+        with:
+          path: |
+            config.cache
+          key: ${{ steps.autoconf-cache-key.outputs.key }}
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Configure tree
+        env:
+          CONFIG_ARGS: >-
+            --cache-file=config.cache
+            --prefix "${{ matrix.cc != 'gcc' && '$PROGRAMFILES/Бактріан🐫' || '$(cygpath "$PROGRAMFILES/Бактріан🐫")'}}"
+            ${{ matrix.cc != 'gcc' && format('--host={0}-pc-windows', matrix.arch) || '' }}
+            ${{ matrix.cc != 'gcc' && format('CC={0}', matrix.cc) || '' }}
+            ${{ matrix.config_arg }}
+        run: |
+          eval $(tools/msvs-promote-path)
+          if ! ./configure ${{ env.CONFIG_ARGS }} ; then
+            rm -rf config.cache
+            failed=0
+            ./configure ${{ env.CONFIG_ARGS }} || failed=$?
+            if ((failed)) ; then
+              echo
+              echo "::group::config.log content ($(wc -l config.log) lines)"
+              cat config.log
+              echo '::endgroup::'
+              exit $failed
+            fi
+          fi
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Save Autoconf cache
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            config.cache
+          key: ${{ steps.autoconf-cache-key.outputs.key }}
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Build OCaml
+        run: |
+          eval $(tools/msvs-promote-path)
+          make -j || failed=$?
+          if ((failed)) ; then make -j1 V=1 ; exit $failed ; fi
+          test -e runtime/libcamlrun.lib || tools/check-symbol-names runtime/*.a otherlibs/*/lib*.a
+          runtime/ocamlrun ocamlc -config
+        if: needs.config.outputs.full-matrix == 'true'
+
+      - name: Assemble backend with mingw-w64 GASM and compare
+        run: |
+          x86_64-w64-mingw32-gcc -c -I./runtime  -I ./flexdll -D__USE_MINGW_ANSI_STDIO=0 -DUNICODE -D_UNICODE -DWINDOWS_UNICODE=1 -DCAMLDLLIMPORT= -DIN_CAML_RUNTIME -DNATIVE_CODE -DTARGET_amd64 -DMODEL_default -DSYS_mingw64 -o runtime/amd64.o runtime/amd64.S
+          dumpbin /disasm:nobytes runtime/amd64nt.obj > runtime/amd64nt.dump
+          awk -f tools/ci/actions/canonicalize-dumpbin.awk runtime/amd64nt.dump runtime/amd64nt.dump > runtime/amd64nt.canonical
+          dumpbin /disasm:nobytes runtime/amd64.o > runtime/amd64.dump
+          awk -f tools/ci/actions/canonicalize-dumpbin.awk runtime/amd64.dump runtime/amd64.dump > runtime/amd64.canonical
+          git diff --no-index -- runtime/amd64*.canonical
+          wc -l runtime/amd64*.dump runtime/amd64*.canonical
+        # ^ The final wc is there to make sure that the canonical files are
+        # reasonable cleaned-up versions of the raw dumpbins and not simply
+        # empty
+        if: endsWith(matrix.arch, '64') && matrix.cc != 'gcc'
+
+      - name: Run the test suite
+        if: needs.config.outputs.full-matrix == 'true' && needs.config.outputs.skip-testsuite != 'true'
+        run: |
+          eval $(tools/msvs-promote-path)
+          make tests
+
+      - name: Install the compiler
+        run: make install
+        if: needs.config.outputs.full-matrix == 'true'
diff --git a/.github/workflows/hygiene.yml b/.github/workflows/hygiene.yml
index 473271f0ab44..3d18f07a3365 100644
--- a/.github/workflows/hygiene.yml
+++ b/.github/workflows/hygiene.yml
@@ -51,20 +51,6 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         if: github.event_name == 'pull_request'
 
-      - name: Parsetree updated
-        run: >-
-          tools/ci/actions/check-parsetree-modified.sh
-          '${{ github.event.pull_request.issue_url }}'
-          '${{ github.ref }}'
-          'pull_request'
-          '${{ github.event.pull_request.base.ref }}'
-          '${{ github.event.pull_request.base.sha }}'
-          '${{ github.event.pull_request.head.ref }}'
-          '${{ github.event.pull_request.head.sha }}'
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        if: github.event_name == 'pull_request'
-
       - name: configure correctly generated
         run: >-
           tools/ci/actions/check-configure.sh
diff --git a/.github/workflows/multicoretests.yml b/.github/workflows/multicoretests.yml
new file mode 100644
index 000000000000..128fe92a5e44
--- /dev/null
+++ b/.github/workflows/multicoretests.yml
@@ -0,0 +1,72 @@
+# Run the multicoretests testsuite if PR is labelled with run-multicoretests
+name: Run multicoretests testsuite
+on:
+  workflow_dispatch:
+
+# Restrict the GITHUB_TOKEN
+permissions: {}
+
+# See build.yml
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ github.event_name == 'pull_request' || github.sha }}
+  cancel-in-progress: true
+
+jobs:
+  multicoretests:
+    if: contains(github.event.pull_request.labels.*.name, 'run-multicoretests')
+    runs-on: 'ubuntu-latest'
+    strategy:
+      matrix:
+        include:
+          - profile: dev
+            ocamlrunparam: b
+          - profile: debug-runtime
+            ocamlrunparam: b,s=4096
+    steps:
+      - name: Checkout OCaml
+        uses: actions/checkout@v5
+        with:
+          path: ocaml
+          persist-credentials: false
+      - name: Configure, build and install OCaml
+        run: |
+          bash -xe ocaml/tools/ci/actions/multicoretests.sh ocaml
+      - name: Checkout multicoretests
+        uses: actions/checkout@v5
+        with:
+          repository: ocaml-multicore/multicoretests
+          ref: 0.11
+          path: multicoretests
+          persist-credentials: false
+      - name: Checkout QCheck
+        uses: actions/checkout@v5
+        with:
+          repository: c-cube/qcheck
+          ref: v0.26
+          path: multicoretests/qcheck
+          persist-credentials: false
+      - name: Checkout dune
+        uses: actions/checkout@v5
+        with:
+          repository: ocaml/dune
+          ref: 3.18.2
+          path: dune
+          persist-credentials: false
+      - name: Build and install dune
+        run: |
+          bash -xe ocaml/tools/ci/actions/multicoretests.sh dune
+      - name: Show the configuration
+        run: |
+          bash ocaml/tools/ci/actions/multicoretests.sh show_config
+      - name: Build the test suite
+        env:
+          DUNE_PROFILE: ${{ matrix.profile }}
+          OCAMLRUNPARAM: ${{ matrix.ocamlrunparam }}
+        run: |
+          bash -xe ocaml/tools/ci/actions/multicoretests.sh build
+      - name: Run the multicore test suite
+        env:
+          DUNE_PROFILE: ${{ matrix.profile }}
+          OCAMLRUNPARAM: ${{ matrix.ocamlrunparam }}
+        run: |
+          bash -xe ocaml/tools/ci/actions/multicoretests.sh testsuite
diff --git a/.github/workflows/parsetree-change.yml b/.github/workflows/parsetree-change.yml
new file mode 100644
index 000000000000..45279561ac29
--- /dev/null
+++ b/.github/workflows/parsetree-change.yml
@@ -0,0 +1,32 @@
+name: Parsetree Updated
+
+on:
+  workflow_dispatch:
+
+jobs:
+  comment-and-label:
+    if: ${{! contains(github.event.pull_request.labels.*.name, 'parsetree-change')}}
+    permissions:
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - name: Notify ppxlib maintainers
+        uses: actions/github-script@v7
+        with:
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: 'CC @ocaml/ppxlib-dev'
+            })
+      - name: Label PR
+        uses: actions/github-script@v7
+        with:
+          script: |
+            github.rest.issues.addLabels({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              labels: ['parsetree-change']
+            })
diff --git a/.github/workflows/tsan.yml b/.github/workflows/tsan.yml
new file mode 100644
index 000000000000..959980d07e8f
--- /dev/null
+++ b/.github/workflows/tsan.yml
@@ -0,0 +1,102 @@
+# Build the compiler and run the testsuite with ThreadSanitizer, if PR is
+# labelled with run-thread-sanitizer
+name: Run testsuite with ThreadSanitizer
+on:
+  workflow_dispatch:
+
+# Restrict the GITHUB_TOKEN
+permissions: {}
+
+# https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#concurrency
+# Concurrent workflows are grouped by the PR or branch that triggered them
+# (github.ref) and the name of the workflow (github.workflow). The
+# 'cancel-in-progress' option then make sure that only one workflow is running
+# at a time. This doesn't prevent new jobs from running, rather it cancels
+# already running jobs before scheduling new jobs.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ github.event_name == 'pull_request' || github.sha }}
+  cancel-in-progress: true
+
+jobs:
+# This job will do the initial build of the compiler (on linux).
+# We then upload the compiler tree as a build artifact to enable re-use in
+# subsequent jobs.
+  build:
+    if: contains(github.event.pull_request.labels.*.name, 'run-thread-sanitizer')
+    runs-on: 'ubuntu-latest'
+    outputs:
+      manual_changed: ${{ steps.manual.outputs.manual_changed }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+        with:
+          persist-credentials: false
+      - name: Install libunwind
+        run: |
+          sudo apt-get update -y
+          sudo apt-get install -y libunwind-dev
+      # This temporary workaround reduces the number of random bits for the base
+      # address of vma regions for mmap allocation, to avoid the
+      # "FATAL: ThreadSanitizer: unexpected memory mapping" TSan error.
+      # See:  https://github.com/google/sanitizers/issues/1716
+      - name: Tune vm.mmap_rnd_bits value for TSan
+        run: sudo sysctl vm.mmap_rnd_bits=28
+      - name: Configure tree
+        run: |
+          MAKE_ARG=-j CONFIG_ARG='--enable-cmm-invariants --enable-dependency-generation --enable-native-toplevel --enable-tsan --enable-ocamltest CPPFLAGS=-DTSAN_INSTRUMENT_ALL' OCAMLRUNPARAM=b,v=0 bash -xe tools/ci/actions/runner.sh configure
+      - name: Build
+        run: |
+          MAKE_ARG=-j bash -xe tools/ci/actions/runner.sh build
+      - name: Prepare Artifact
+        run: tar --zstd -cf /tmp/sources.tar.zstd .
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: compiler
+          path: /tmp/sources.tar.zstd
+          retention-days: 1
+
+# Testsuite run jobs:
+# normal: Run the full testsuite
+# debug: Run the full testsuite with the debug runtime and minor heap
+#        verification.
+  normal:
+    if: contains(github.event.pull_request.labels.*.name, 'run-thread-sanitizer')
+    name: ${{ matrix.name }}
+    needs: build
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - id: normal
+            name: normal
+            dependencies: libunwind-dev
+          - id: debug
+            name: debug runtime
+            dependencies: libunwind-dev
+    steps:
+      - name: Download Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: compiler
+      - name: Unpack Artifact
+        run: |
+          tar --zstd -xf sources.tar.zstd
+          rm -f sources.tar.zstd
+      - name: Packages
+        if: matrix.dependencies != ''
+        run: |
+          sudo apt-get update -y
+          sudo apt-get install -y ${{ matrix.dependencies }}
+      - name: Run the testsuite
+        if: matrix.id == 'normal'
+        # Run testsuite with 30-minute timeout per test
+        run: |
+          TIMEOUT=1800 TSAN_OPTIONS=history_size=6 OCAMLRUNPARAM=b,v=0 bash -xe tools/ci/actions/runner.sh test_sequential
+      - name: Run the testsuite (debug runtime)
+        if: matrix.id == 'debug'
+        env:
+          OCAMLRUNPARAM: v=0,V=1
+          USE_RUNTIME: d
+        run: |
+          bash -cxe "TSAN_OPTIONS=history_size=6 SHOW_TIMINGS=1 tools/ci/actions/runner.sh test_sequential"
diff --git a/tools/ci/actions/check-parsetree-modified.sh b/tools/ci/actions/check-parsetree-modified.sh
deleted file mode 100755
index 3438bb9c8acd..000000000000
--- a/tools/ci/actions/check-parsetree-modified.sh
+++ /dev/null
@@ -1,54 +0,0 @@
-#!/usr/bin/env bash
-#**************************************************************************
-#*                                                                        *
-#*                                 OCaml                                  *
-#*                                                                        *
-#*                 Paul-Elliot Anglès d'Auriac, Tarides                   *
-#*                                                                        *
-#*   Copyright 2023 Tarides                                               *
-#*                                                                        *
-#*   All rights reserved.  This file is distributed under the terms of    *
-#*   the GNU Lesser General Public License version 2.1, with the          *
-#*   special exception on linking described in the file LICENSE.          *
-#*                                                                        *
-#**************************************************************************
-
-set -e
-
-# Hygiene Checks: check that whenever the parsetree.mli file has been modified,
-# the parsetree-change label has been applied to the PR
-
-# Exactly of the following must be true:
-#   - No commit in the PR alters the parsetree.mli file
-#   - The parsetree-change label is applied to the PR
-
-API_URL="$1"
-shift 1
-
-AUTH="authorization: Bearer $GITHUB_TOKEN"
-
-# We need all the commits in the PR to be available
-. tools/ci/actions/deepen-fetch.sh
-
-COMMIT_RANGE="$MERGE_BASE..$PR_HEAD"
-
-LABEL='parsetree-change'
-
-if ! git diff "$COMMIT_RANGE" --name-only --exit-code parsing/parsetree.mli \
-   > /dev/null; then
-  echo -e "The parsetree has been modified."
-  if curl --silent --header "$AUTH" "$API_URL/labels" | grep -q "$LABEL"; then
-    echo -e "Label $LABEL is assigned to the PR."
-  else
-    echo -e "Please assign the label $LABEL to the PR"
-    exit 1
-  fi
-else
-  echo -e "The parsetree has not been modified."
-  if curl --silent --header "$AUTH" "$API_URL/labels" | grep -q "$LABEL"; then
-    echo -e "Please remove the label $LABEL to the PR"
-    exit 1
-  else
-    echo -e "Label $LABEL is not assigned to the PR"
-  fi
-fi
diff --git a/tools/ci/actions/multicoretests.sh b/tools/ci/actions/multicoretests.sh
new file mode 100755
index 000000000000..4adbd99294e6
--- /dev/null
+++ b/tools/ci/actions/multicoretests.sh
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+#**************************************************************************
+#*                                                                        *
+#*                                 OCaml                                  *
+#*                                                                        *
+#*                           Samuel Hym, Tarides                          *
+#*                                                                        *
+#*   Copyright 2024 Tarides                                               *
+#*                                                                        *
+#*   All rights reserved.  This file is distributed under the terms of    *
+#*   the GNU Lesser General Public License version 2.1, with the          *
+#*   special exception on linking described in the file LICENSE.          *
+#*                                                                        *
+#**************************************************************************
+
+set -e
+
+OCAMLDIR=ocaml
+DUNEDIR=dune
+MULTICORETESTSDIR=multicoretests
+
+export PREFIX="$HOME/local"
+export PATH="$PREFIX/bin:$PATH"
+
+fatal() {
+  printf %s "$1"
+  exit 1
+}
+
+build_ocaml() {
+  # We let build.yml test for warnings
+  cd "$OCAMLDIR"
+  if ! ./configure --disable-warn-error --disable-stdlib-manpages \
+      --disable-ocamltest --disable-ocamldoc --prefix="$PREFIX" ; then
+    echo
+    echo "::group::config.log content ($(wc -l config.log) lines)"
+    cat config.log
+    echo '::endgroup::'
+    exit 1
+  fi
+
+  make -j
+  make install
+}
+
+build_dune() {
+  cd "$DUNEDIR"
+  make release
+  make install PREFIX="$PREFIX"
+}
+
+show_config() {
+  set -x
+  ocamlc -config
+  dune --version
+}
+
+build_testsuite() {
+  cd "$MULTICORETESTSDIR"
+  dune build
+}
+
+run_testsuite() {
+  export QCHECK_MSG_INTERVAL=60
+  cd "$MULTICORETESTSDIR"
+  dune build @ci -j1 --no-buffer --display=quiet --cache=disabled \
+    --error-reporting=twice
+}
+
+case "$1" in
+  ocaml)
+    build_ocaml
+    ;;
+  dune)
+    build_dune
+    ;;
+  show_config)
+    show_config
+    ;;
+  build)
+    build_testsuite
+    ;;
+  testsuite)
+    run_testsuite
+    ;;
+  *)
+    fatal "Unknown command '$1'"
+    ;;
+esac
diff --git a/tools/ci/actions/runner.sh b/tools/ci/actions/runner.sh
index c3fe798a9234..0c9a4f55c044 100755
--- a/tools/ci/actions/runner.sh
+++ b/tools/ci/actions/runner.sh
@@ -109,6 +109,15 @@ Test () {
   fi
 }
 
+# By default, TestPrefix will attempt to run the tests
+# in the given directory in parallel.
+TestPrefix () {
+  TO_RUN=parallel-"$1"
+  echo Running single testsuite directory with $TO_RUN
+  $MAKE -C testsuite $TO_RUN
+  cd ..
+}
+
 API_Docs () {
   echo Ensuring that all library documentation compiles
   $MAKE -C api_docgen html pdf texi
@@ -205,6 +214,7 @@ configure) Configure;;
 build) Build;;
 test) Test parallel;;
 test_sequential) Test sequential;;
+test_prefix) TestPrefix $2;;
 api-docs) API_Docs;;
 install) Install;;
 manual) BuildManual;;

From b2a660d7983fa61189e89f1e8a6352695b002a80 Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Thu, 26 Mar 2026 17:55:14 +0000
Subject: [PATCH 2/7] Temporary AppVeyor reconfiguration

---
 appveyor.yml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/appveyor.yml b/appveyor.yml
index b5497a4b6198..7f2465fec0d8 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -18,6 +18,9 @@ branches:
     - /5\.*/
     - trunk
 
+# Do not build feature branch with open Pull Requests
+skip_branch_with_pr: true
+
 # Compile the 64 bits version
 platform:
   - x64

From 8a0027ba4390f933d9727ca2a6e032410e04b9c6 Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Wed, 14 Dec 2022 00:52:52 +0100
Subject: [PATCH 3/7] Don't install ocamloptp without ocamlopt

A side-effect of PR#11675 was that ocamloptp stopped being installed
when the native compiler is not built.
---
 Changes        | 3 +++
 tools/Makefile | 5 ++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/Changes b/Changes
index 0a10fa02a17b..b21d16a089c5 100644
--- a/Changes
+++ b/Changes
@@ -121,6 +121,9 @@ OCaml 4.14.2 (14 March 2024)
 - #11590: Allow installing to a destination path containing spaces.
   (Élie Brami, review by Sébastien Hinderer and David Allsopp)
 
+- #11675: Stop installing ocamloptp when the native compiler is not built.
+  (Sébastien Hinderer, review by David Allsopp and Florian Angeletti)
+
 - #12372: Pass option -no-execute-only to the linker for OpenBSD >= 7.3
   so that code sections remain readable, as needed for closure marshaling.
   (Xavier Leroy and Anil Madhavapeddy, review by Anil Madhavapeddy and
diff --git a/tools/Makefile b/tools/Makefile
index 094f213e04c9..f51ed1709e92 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -23,8 +23,11 @@ include $(ROOTDIR)/Makefile.common
 # Setup GNU make variables storing per-target source and target,
 # a list of installed tools, and a function to quote a filename for
 # the shell.
-installed_tools := ocamldep ocamlprof ocamlcp ocamloptp \
+installed_tools := ocamldep ocamlprof ocamlcp \
                    ocamlmktop ocamlmklib ocamlobjinfo
+ifeq "$(NATIVE_COMPILER)" "true"
+installed_tools += ocamloptp
+endif
 
 install_files :=
 define byte2native

From aa35d1a87fc70d07e105928de2c21bbce2a7fcaa Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Mon, 23 Mar 2026 08:10:18 +0000
Subject: [PATCH 4/7] Document the CI unity process

---
 tools/ci/README.md | 158 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 158 insertions(+)
 create mode 100644 tools/ci/README.md

diff --git a/tools/ci/README.md b/tools/ci/README.md
new file mode 100644
index 000000000000..3e3b4b20a82a
--- /dev/null
+++ b/tools/ci/README.md
@@ -0,0 +1,158 @@
+# OCaml CI Infrastructure
+
+## Unified CI
+
+During the 5.2 development cycle, the CI configurations were synchronised in
+[#12846][], [#12847][], [#12848][] and [#12849][]. This series of PRs focused on
+`.github/workflows`, `tools/ci/actions`, `tools/ci-appveyor` and `appveyor.yml`.
+Subsequent work has extended this to the Jenkins configurations in
+`tools/ci/inria`.
+
+Following those PRs, additional changes to the CI configurations are freely
+back-ported. Keeping the CI workflows running for old compilers occasionally
+necessitates backporting non-CI related changes, typically because of C compiler
+changes. These are:
+
+- [98a24eaaeef][] (from [#10831][]) was cherry-picked to 4.14 in order to
+  support [#13065][]. The issue was masked previously because `macos-latest`
+  flipped over to an arm64 image, which skips the unwind test for architecture
+  reasons; but switching back to amd64 testing re-revealed the problem with the
+  script.
+- [#12231][] was backported to 5.0 (but is not needed in 4.x). It is required in
+  order to compile the branch with mingw-w64 11.0, otherwise the testsuite will
+  fail with flexdll relocation errors.
+- [#11861][] and [#12509][] were backported to 5.0 (4.14 already has [#12577][]
+  including both of these). These are necessary for macOS CI, as clang in C17
+  mode emits warnings otherwise.
+- [#13019][] was backported to 5.1 and 5.0 (4.14 already has [#13018][]). As of
+  March 2024, this change is required for the testsuite to pass when running on
+  Apple silicon to eliminate linker warnings.
+- [c9f4c113e5][] was added to 4.14 to disable the `lib-threads/beat.ml` test on
+  macOS only (see [#13339][] for more details).
+
+## Maintenance notes
+
+PRs which touch GitHub Actions are shown with:
+
+```
+git log --first-parent --oneline upstream/trunk -- .github/workflows appveyor.yml tools/ci
+```
+
+PRs which are entirely CI-related are simply back-ported as normal with
+(`git cherry-pick -x -m1 ...`). PRs which are primarily a feature/fix which
+happen to contain a CI change have the commit message altered to
+`Unified CI cherry-pick: PR#nnnnn` to make it explicit that the feature itself
+hasn't been back-ported.
+
+PRs which have to be back-ported in order to allow CI to work are listed above,
+and do not have the GitHub PR number "neutered" in commit messages.
+
+GitHub insists on spamming GitHub PR conversations for every single rebase while
+testing the branches on a fork. While testing the branches, it's worth neutering
+all references to PRs in the commit messages (PR#xxxxx, rather than #xxxxx) and
+changing them just before the final push to upstream. In the final version of
+the branch, only back-ported features should have the `PR#` changed back to `#`.
+
+Last sync'd: 20-Mar-2026 with #14612
+
+## Branch differences
+
+As far as possible, this process keeps `.github/workflows`, `appveyor.yml` and
+`tools/ci` are kept in sync, with the exception on all release branches of
+`.github/workflows/stale.yml`, which is deleted early after branching.
+Naturally, features not present in older versions of OCaml can be neither tested
+nor relied on. In general, CI workflows and supporting scripts are backported,
+but then minimally disabled, as this allows subsequent changes on trunk to be
+mechanically cherry-picked. Each branch can be compared with
+
+```
+git diff upstream/5.5 upstream/trunk -- .github/workflows appveyor.yml tools/ci
+```
+
+The differences on each branch are:
+
+trunk:
+- [#14421][] allows `sockaddr_cxx.ml` to run on Jenkins
+5.5
+- [#14240][] allows hacks around `pthread_cancel` to be removed from
+  `build-cross.yml`
+- Relocatable OCaml ([#14014][], [#14244][], [#14245][] and [#14246][]) add
+  various matrix tests
+- [#14310][] requires the addition of a C++ compiler in CI
+- [#14424][] allows `--disable-dependency-generation` to be used more sparingly
+- [#14563][] requires updates to the remove-sinh-primitive.patch used to test
+  the bootstrap
+5.4
+- [#13199][] (and others) add debugger testing in CI
+- [#13431][] adds `parsetree-change.yml`
+- [#13458][] adds `multicoretests.yml`
+- [#13526][] adds `build-cross.yml`
+- [#13667][] adds `--enable-codegen-invariants`
+5.3
+- [#12904][] enables the TSAN workflow in CI
+- [#12954][] means `build-msvc.yml` actually builds MSVC and requires
+  winpthreads support in Jenkins
+- [#13293][] improves the sanitizers Jenkins check
+- [#13668][] adds a requirement for `luatex` for building the manual
+5.2
+- [#12321][] requires a tweak to AppVeyor for rebuilding ocamltest
+- [#12514][] allows the Cygwin testsuite to be run on a CRLF checkout
+- [#12644][] re-enables TSAN testing on Jenkins
+- [#12652][] changes the way the magic numbers are bumped
+- [#12843][] means i386 testing can switch to Debian 13 (and GNU make 4.4.1)
+5.1
+- [#11144][] allows frame pointers mode to be tested in Jenkins
+- [#11642][] allows Cygwin to be tested in CI
+5.0
+- OCaml 5.x workflow alterations
+- [#10926][] allows otherlibs C symbol names to be checked in CI
+- [#11294][] means autoconf 2.69 no longer has to be installed in CI
+- [#11389][] switched AppVeyor testing to use its Visual Studio 2022 image
+4.14
+- [#10690][] adds `--enable-native-toplevel`, replacing the manual compilation
+  of `ocamlnat`
+
+[#10690]: https://github.com/ocaml/ocaml/pull/10690
+[#10831]: https://github.com/ocaml/ocaml/pull/10831
+[#10926]: https://github.com/ocaml/ocaml/pull/10926
+[#11144]: https://github.com/ocaml/ocaml/pull/11144
+[#11294]: https://github.com/ocaml/ocaml/pull/11294
+[#11389]: https://github.com/ocaml/ocaml/pull/11389
+[#11642]: https://github.com/ocaml/ocaml/pull/11642
+[#11861]: https://github.com/ocaml/ocaml/pull/11861
+[#12231]: https://github.com/ocaml/ocaml/pull/12231
+[#12321]: https://github.com/ocaml/ocaml/pull/12321
+[#12509]: https://github.com/ocaml/ocaml/pull/12509
+[#12514]: https://github.com/ocaml/ocaml/pull/12514
+[#12577]: https://github.com/ocaml/ocaml/pull/12577
+[#12644]: https://github.com/ocaml/ocaml/pull/12644
+[#12652]: https://github.com/ocaml/ocaml/pull/12652
+[#12843]: https://github.com/ocaml/ocaml/pull/12843
+[#12846]: https://github.com/ocaml/ocaml/pull/12846
+[#12847]: https://github.com/ocaml/ocaml/pull/12847
+[#12848]: https://github.com/ocaml/ocaml/pull/12848
+[#12849]: https://github.com/ocaml/ocaml/pull/12849
+[#12904]: https://github.com/ocaml/ocaml/pull/12904
+[#12954]: https://github.com/ocaml/ocaml/pull/12954
+[#13018]: https://github.com/ocaml/ocaml/pull/13018
+[#13019]: https://github.com/ocaml/ocaml/pull/13019
+[#13065]: https://github.com/ocaml/ocaml/pull/13065
+[#13199]: https://github.com/ocaml/ocaml/pull/13199
+[#13293]: https://github.com/ocaml/ocaml/pull/13293
+[#13339]: https://github.com/ocaml/ocaml/pull/13339
+[#13431]: https://github.com/ocaml/ocaml/pull/13431
+[#13458]: https://github.com/ocaml/ocaml/pull/13458
+[#13526]: https://github.com/ocaml/ocaml/pull/13526
+[#13667]: https://github.com/ocaml/ocaml/pull/13667
+[#13668]: https://github.com/ocaml/ocaml/pull/13668
+[#14014]: https://github.com/ocaml/ocaml/pull/14014
+[#14240]: https://github.com/ocaml/ocaml/pull/14240
+[#14244]: https://github.com/ocaml/ocaml/pull/14244
+[#14245]: https://github.com/ocaml/ocaml/pull/14245
+[#14246]: https://github.com/ocaml/ocaml/pull/14246
+[#14310]: https://github.com/ocaml/ocaml/pull/14310
+[#14421]: https://github.com/ocaml/ocaml/pull/14421
+[#14424]: https://github.com/ocaml/ocaml/pull/14424
+[#14563]: https://github.com/ocaml/ocaml/pull/14563
+[98a24eaaeef]: https://github.com/ocaml/ocaml/commit/98a24eaaeefaa714f03427f763d73dca87f56e4d
+[c9f4c113e5]: https://github.com/ocaml/ocaml/commit/c9f4c113e51f0602207b88169181810eb52c228a

From 591e25a4c8313c7163afbc4b22eade4afb7fbcc2 Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Tue, 24 Mar 2026 08:22:11 +0000
Subject: [PATCH 5/7] Extend to 4.08-4.13

---
 tools/ci/README.md | 118 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 109 insertions(+), 9 deletions(-)

diff --git a/tools/ci/README.md b/tools/ci/README.md
index 3e3b4b20a82a..0e7d79514100 100644
--- a/tools/ci/README.md
+++ b/tools/ci/README.md
@@ -13,22 +13,51 @@ back-ported. Keeping the CI workflows running for old compilers occasionally
 necessitates backporting non-CI related changes, typically because of C compiler
 changes. These are:
 
-- [98a24eaaeef][] (from [#10831][]) was cherry-picked to 4.14 in order to
+- [#8650][] backported to 4.08 and 4.09 as a prerequisite for testing with
+  `make --warn-undefined-variables`.
+- [#9414][] backported to 4.08-4.10 adding `KEEP_TEST_DIR_ON_SUCCESS` support to
+  the testsuite, necessary to Jenkins workers.
+- [#9437][] backported to 4.08 and 4.09 to fix compilation on modern FreeBSD.
+- [#9557][] backported to 4.08-4.10 to fix compilation on modern POWER.
+- [98a24eaaeef][] (from [#10831][]) was cherry-picked to 4.08-4.14 in order to
   support [#13065][]. The issue was masked previously because `macos-latest`
   flipped over to an arm64 image, which skips the unwind test for architecture
   reasons; but switching back to amd64 testing re-revealed the problem with the
   script.
+- [#9981][] backported to 4.08 and 4.09 to fix linking errors with Clang.
+- [#10046][] backported to 4.08-4.11 to compile DLLs with `-static-libgcc` to
+  fix compilation with mingw-w64 runtime 8.0.0+.
+- [#10148][] backported to 4.11 and 4.12, trivially fixing a GCC warning.
+- [#10045][] backported to 4.08-4.12 to allow the C# tests to run on mingw-w64.
+- [#9919][] partially backported to 4.10-4.12 as it's a prerequisite of
+  [#12577][]. `caml_do_exit` is needed to avoid declaring `caml_sys_exit` with
+  two different prototypes; not needed for 4.08 and 4.09, because the change
+  affects `-output-complete-exe`, which was introduced in 4.10.
+- [#10380][] backported to 4.10-4.12 fixing compilation with non C-locale
+  characters in `--prefix` on Windows (4.08 and 4.09 not affected because they
+  don't attempt to normalise the prefix).
+- [#10835][] backported to 4.08-4.13 to fix 32bit Unix shared compilation.
+- [#10723][] backported to 4.08-4.13 to fix compilation on macOS
+- [#11100][] backported to 4.08-4.14 to stop linker output from old versions of
+  Xcode tools causing unexpected errors in the testsuite.
+- [#11675][] backported to 4.08 and 4.10-5.0. This PR indirectly fixed a bug
+  that `ocamloptp` is installed even when ocamlopt isn't built.
 - [#12231][] was backported to 5.0 (but is not needed in 4.x). It is required in
   order to compile the branch with mingw-w64 11.0, otherwise the testsuite will
   fail with flexdll relocation errors.
-- [#11861][] and [#12509][] were backported to 5.0 (4.14 already has [#12577][]
-  including both of these). These are necessary for macOS CI, as clang in C17
-  mode emits warnings otherwise.
-- [#13019][] was backported to 5.1 and 5.0 (4.14 already has [#13018][]). As of
-  March 2024, this change is required for the testsuite to pass when running on
-  Apple silicon to eliminate linker warnings.
-- [c9f4c113e5][] was added to 4.14 to disable the `lib-threads/beat.ml` test on
-  macOS only (see [#13339][] for more details).
+- [#12372][] backported to 4.08-4.13 and 5.0 to fix compilation on OpenBSD.
+- [#12520][] backported to 4.08-4.13, to provide support for testing
+  `configure.ac`.
+- [#11861][] and [#12509][] were backported to 5.0 and 4.14's [#12577][] version
+  to 4.08-4.13. These are necessary for macOS CI, as clang in C17 mode emits
+  warnings otherwise.
+- [#12993][] backported from 4.14 to 4.08-4.13 to fix 32bit Unix compilation.
+- [#13019][] was backported to 5.1 and 5.0 and 4.14's [#13018][] version to
+  4.08-4.13. As of March 2024, this change is required for the testsuite to pass
+  when running on Apple silicon to eliminate linker warnings.
+- [c9f4c113e5][] was added to 4.08-4.14 to disable the `lib-threads/beat.ml`
+  test on macOS only (see [#13339][] for more details).
+- [#14607][] backported from 4.14 to 4.11-4.13 to fix RISC-V shared compilation.
 
 ## Maintenance notes
 
@@ -111,19 +140,88 @@ trunk:
 4.14
 - [#10690][] adds `--enable-native-toplevel`, replacing the manual compilation
   of `ocamlnat`
+4.13
+- [#944][] updates to the remove-sinh-primitive.patch used to test the bootstrap
+- [#1400][] adds `--enable-cmm-invariants`
+- [#9996][] changes the way the API documentation build commands are invoked
+- [#10135][] means flexdll no longer has to be explicitly built on AppVeyor and
+  Jenkins
+- [#10336][] restores CI checking of the manual
+4.12
+- [#9332][] adds `--disable-dependency-generation`
+- [#9625][] adds `--enable-warn-error`, removing the need for configuration
+  hacks in AppVeyor
+- [#9669][] adds macOS arm64 support
+- [#9745][] synchronises the labelled/unlabelled standard library interfaces
+- [#9824][] allows the sanitizers script to configure the compiler less hackily
+- [#9927][] restores shared library support in Cygwin64
+- [#10063][] re-enables Solaris support
+4.11
+- [#9250][] adds `--enable-ocamltest` (prior to that ocamltest was guaranteed to
+  be built)
+- [#9441][] adds RISC-V support
+- [#10026][] macOS arm64 support was only applied to 4.10
+4.10
+- [#8790][] adds case-insensitive name-collision checks to the manual
+- [#8835][] adds `--disable-stdlib-manpages`
+- [#8951][] adds a default `Makefile` target to the compiler
+- [#10026][] backports macOS arm64 from [#9669][] in 4.12
+4.09
+- [#2289][] removes the vmthreads library (a non-obvious side-effect of this is
+  that it fixes `make alldepend` on Windows)
+- [#2318][] removes the graphics library
+- [#8537][] makes flexdll/flexlink.exe a normal executable, removing a special
+  case in the AppVeyor script
 
+[#944]: https://github.com/ocaml/ocaml/pull/944
+[#1400]: https://github.com/ocaml/ocaml/pull/1400
+[#2289]: https://github.com/ocaml/ocaml/pull/2289
+[#2318]: https://github.com/ocaml/ocaml/pull/2318
+[#8537]: https://github.com/ocaml/ocaml/pull/8537
+[#8650]: https://github.com/ocaml/ocaml/pull/8650
+[#8790]: https://github.com/ocaml/ocaml/pull/8790
+[#8835]: https://github.com/ocaml/ocaml/pull/8835
+[#8951]: https://github.com/ocaml/ocaml/pull/8951
+[#9250]: https://github.com/ocaml/ocaml/pull/9250
+[#9332]: https://github.com/ocaml/ocaml/pull/9332
+[#9414]: https://github.com/ocaml/ocaml/pull/9414
+[#9437]: https://github.com/ocaml/ocaml/pull/9437
+[#9441]: https://github.com/ocaml/ocaml/pull/9441
+[#9557]: https://github.com/ocaml/ocaml/pull/9557
+[#9625]: https://github.com/ocaml/ocaml/pull/9625
+[#9669]: https://github.com/ocaml/ocaml/pull/9669
+[#9745]: https://github.com/ocaml/ocaml/pull/9745
+[#9824]: https://github.com/ocaml/ocaml/pull/9824
+[#9919]: https://github.com/ocaml/ocaml/pull/9919
+[#9927]: https://github.com/ocaml/ocaml/pull/9927
+[#9981]: https://github.com/ocaml/ocaml/pull/9981
+[#9996]: https://github.com/ocaml/ocaml/pull/9996
+[#10026]: https://github.com/ocaml/ocaml/pull/10026
+[#10045]: https://github.com/ocaml/ocaml/pull/10045
+[#10046]: https://github.com/ocaml/ocaml/pull/10046
+[#10063]: https://github.com/ocaml/ocaml/pull/10063
+[#10135]: https://github.com/ocaml/ocaml/pull/10135
+[#10148]: https://github.com/ocaml/ocaml/pull/10148
+[#10336]: https://github.com/ocaml/ocaml/pull/10336
+[#10380]: https://github.com/ocaml/ocaml/pull/10380
 [#10690]: https://github.com/ocaml/ocaml/pull/10690
+[#10723]: https://github.com/ocaml/ocaml/pull/10723
 [#10831]: https://github.com/ocaml/ocaml/pull/10831
+[#10835]: https://github.com/ocaml/ocaml/pull/10835
 [#10926]: https://github.com/ocaml/ocaml/pull/10926
+[#11100]: https://github.com/ocaml/ocaml/pull/11100
 [#11144]: https://github.com/ocaml/ocaml/pull/11144
 [#11294]: https://github.com/ocaml/ocaml/pull/11294
 [#11389]: https://github.com/ocaml/ocaml/pull/11389
 [#11642]: https://github.com/ocaml/ocaml/pull/11642
+[#11675]: https://github.com/ocaml/ocaml/pull/11675
 [#11861]: https://github.com/ocaml/ocaml/pull/11861
 [#12231]: https://github.com/ocaml/ocaml/pull/12231
 [#12321]: https://github.com/ocaml/ocaml/pull/12321
+[#12372]: https://github.com/ocaml/ocaml/pull/12372
 [#12509]: https://github.com/ocaml/ocaml/pull/12509
 [#12514]: https://github.com/ocaml/ocaml/pull/12514
+[#12520]: https://github.com/ocaml/ocaml/pull/12520
 [#12577]: https://github.com/ocaml/ocaml/pull/12577
 [#12644]: https://github.com/ocaml/ocaml/pull/12644
 [#12652]: https://github.com/ocaml/ocaml/pull/12652
@@ -134,6 +232,7 @@ trunk:
 [#12849]: https://github.com/ocaml/ocaml/pull/12849
 [#12904]: https://github.com/ocaml/ocaml/pull/12904
 [#12954]: https://github.com/ocaml/ocaml/pull/12954
+[#12993]: https://github.com/ocaml/ocaml/pull/12993
 [#13018]: https://github.com/ocaml/ocaml/pull/13018
 [#13019]: https://github.com/ocaml/ocaml/pull/13019
 [#13065]: https://github.com/ocaml/ocaml/pull/13065
@@ -154,5 +253,6 @@ trunk:
 [#14421]: https://github.com/ocaml/ocaml/pull/14421
 [#14424]: https://github.com/ocaml/ocaml/pull/14424
 [#14563]: https://github.com/ocaml/ocaml/pull/14563
+[#14607]: https://github.com/ocaml/ocaml/pull/14607
 [98a24eaaeef]: https://github.com/ocaml/ocaml/commit/98a24eaaeefaa714f03427f763d73dca87f56e4d
 [c9f4c113e5]: https://github.com/ocaml/ocaml/commit/c9f4c113e51f0602207b88169181810eb52c228a

From dc735bd8239e49b704846c51db05909d76afd5b5 Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Tue, 31 Mar 2026 21:22:57 +0100
Subject: [PATCH 6/7] Fix noise in check-configure.sh

If multiple commits are being checked, a second git branch would be
resetting a checked out branch, which cuases a warning to be emitted.
---
 tools/ci/actions/check-configure.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/ci/actions/check-configure.sh b/tools/ci/actions/check-configure.sh
index e8e764739fb1..6b5797b89aec 100755
--- a/tools/ci/actions/check-configure.sh
+++ b/tools/ci/actions/check-configure.sh
@@ -54,7 +54,7 @@ fi
 CheckTree () {
   local RET=0
   COMMIT="$1"
-  git branch -qf 'return'
+  git checkout -qB 'return'
   git checkout -q "$COMMIT"
   mv configure configure.ref
   tools/autogen autoconf2.69
@@ -66,6 +66,7 @@ CheckTree () {
       "$COMMIT: \e[${COLOR}mconfigure.ac doesn't generate configure\e[0m\n"
   fi
   mv configure.ref configure
+  git reset --hard -q HEAD
   git checkout -q 'return'
   return $RET
 }

From 9fe698f70644d84bb11e10557e013879a12ee1ab Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Thu, 9 Apr 2026 19:20:22 +0100
Subject: [PATCH 7/7] Set NATIVE_COMPILER consistently

Prior to 5.0, NATIVE_COMPILER was only set to false if the native
compiler was explicitly disabled, but remained true even if the
architecture wasn't supported.
---
 configure    | 4 ++++
 configure.ac | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index 201d1c8396d5..9d74eeef1df3 100755
--- a/configure
+++ b/configure
@@ -14439,9 +14439,13 @@ if test x"$enable_native_compiler" = "xno"; then :
   native_compiler=false
   { $as_echo "$as_me:${as_lineno-$LINENO}: the native compiler is disabled" >&5
 $as_echo "$as_me: the native compiler is disabled" >&6;}
+else
+  if test x"$arch" = 'xnone'; then :
+  native_compiler=false
 else
   native_compiler=true
 fi
+fi
 
 if ! $native_compiler; then :
   natdynlink=false
diff --git a/configure.ac b/configure.ac
index 462a3c4324aa..c17d3fbc21f4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1176,7 +1176,9 @@ AS_CASE([$host],
 AS_IF([test x"$enable_native_compiler" = "xno"],
   [native_compiler=false
   AC_MSG_NOTICE([the native compiler is disabled])],
-  [native_compiler=true])
+  [AS_IF([test x"$arch" = 'xnone'],
+    [native_compiler=false],
+    [native_compiler=true])])
 
 AS_IF([! $native_compiler], [natdynlink=false])