gitlab-ci: split into multiple files

Also add comments for sections to make it easier to figure out what's
going on.

Also rename the `cmake_test_unix_package` to be Linux-specific since it
actually is.
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 438510c..3fa3f55 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,472 +1,21 @@
-.manual_rules_settings: &manual_rules_settings
-    - if: '$CI_PROJECT_PATH == "cmake/cmake"'
-      when: delayed
-      start_in: 5 minutes
-    - if: '$CI_MERGE_REQUEST_ID'
-      when: manual
-    - when: never
+include:
+    # Metadata shared my many jobs
+    - local: .gitlab/rules.yml
+    - local: .gitlab/artifacts.yml
 
-.rules_settings: &rules_settings
-    - if: '$CI_PROJECT_PATH == "cmake/cmake"'
-      when: always
-    - if: '$CI_MERGE_REQUEST_ID'
-      when: always
-    - when: never
-
-.release_linux: &release_linux
-    image: "kitware/cmake:build-linux-x86_64-deps-2020-04-02@sha256:77e9ab183f34680990db9da5945473e288f0d6556bce79ecc1589670d656e157"
-
-    variables:
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
-        LAUNCHER: "scl enable devtoolset-6 rh-python36 --"
-
-.fedora31: &fedora31
-    image: "kitware/cmake:ci-fedora31-x86_64-2020-06-01"
-
-    variables:
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
-
-.debian10: &debian10
-    image: "kitware/cmake:ci-debian10-x86_64-2020-04-27"
-
-    variables:
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
-
-.debian10_iwyu: &debian10_iwyu
-    extends: .debian10
-
-    variables:
-        CMAKE_CONFIGURATION: debian10_iwyu
-        CTEST_NO_WARNINGS_ALLOWED: 1
-        CMake_SKIP_INSTALL: 1
-
-.fedora31_tidy: &fedora31_tidy
-    extends: .fedora31
-
-    variables:
-        CMAKE_CONFIGURATION: fedora31_tidy
-        CTEST_NO_WARNINGS_ALLOWED: 1
-        CMake_SKIP_INSTALL: 1
-
-.fedora31_sphinx: &fedora31_sphinx
-    extends: .fedora31
-
-    variables:
-        CMAKE_CONFIGURATION: fedora31_sphinx
-        CTEST_NO_WARNINGS_ALLOWED: 1
-        CTEST_SOURCE_SUBDIRECTORY: "Utilities/Sphinx"
-        CMake_SKIP_INSTALL: 1
-
-.fedora31_ninja: &fedora31_ninja
-    extends: .fedora31
-
-    variables:
-        CMAKE_CONFIGURATION: fedora31_ninja
-        CTEST_NO_WARNINGS_ALLOWED: 1
-
-.fedora31_ninja_multi: &fedora31_ninja_multi
-    extends: .fedora31
-
-    variables:
-        CMAKE_CONFIGURATION: fedora31_ninja_multi
-        CTEST_NO_WARNINGS_ALLOWED: 1
-        CMAKE_GENERATOR: "Ninja Multi-Config"
-
-.fedora31_makefiles: &fedora31_makefiles
-    extends: .fedora31
-
-    variables:
-        CMAKE_CONFIGURATION: fedora31_makefiles
-        CTEST_NO_WARNINGS_ALLOWED: 1
-        CMAKE_GENERATOR: "Unix Makefiles"
-
-.cuda10.2: &cuda
-    image: "kitware/cmake:ci-cuda10.2-x86_64-2020-06-11"
-
-    variables:
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
-        CTEST_LABELS: "CUDA"
-
-.cuda10.2_nvidia: &cuda10_2_nvidia
-    extends: .cuda10.2
-
-    variables:
-        CMAKE_CONFIGURATION: cuda10.2_nvidia
-        CTEST_NO_WARNINGS_ALLOWED: 1
-
-.macos: &macos
-    variables:
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci ext/$CI_CONCURRENT_ID"
-        # TODO: Factor this out so that each job selects the Xcode version to
-        # use so that different versions can be tested in a single pipeline.
-        DEVELOPER_DIR: "/Applications/Xcode-11.5.app/Contents/Developer"
-
-.macos_build: &macos_build
-    extends: .macos
-
-    variables:
-        # Note that shell runners only support runners with a single
-        # concurrency level. We can't use `$CI_CONCURRENCY_ID` because this may
-        # change between the build and test stages which CMake doesn't support.
-        # Even if we could, it could change if other runners on the machine
-        # could run at the same time, so we drop it.
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
-
-.macos_ninja: &macos_ninja
-    extends: .macos_build
-
-    variables:
-        CMAKE_CONFIGURATION: macos_ninja
-        CTEST_NO_WARNINGS_ALLOWED: 1
-
-.macos_makefiles: &macos_makefiles
-    extends: .macos_build
-
-    variables:
-        CMAKE_CONFIGURATION: macos_makefiles
-        CTEST_NO_WARNINGS_ALLOWED: 1
-        CMAKE_GENERATOR: "Unix Makefiles"
-
-.macos_xcode: &macos_xcode
-    extends: .macos
-
-    variables:
-        CMAKE_CONFIGURATION: macos_xcode
-        CMAKE_GENERATOR: Xcode
-
-.windows: &windows
-    variables:
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR\\cmake ci ext\\$CI_CONCURRENT_ID"
-
-.windows_build: &windows_build
-    extends: .windows
-
-    variables:
-        # Note that shell runners only support runners with a single
-        # concurrency level. We can't use `$CI_CONCURRENCY_ID` because this may
-        # change between the build and test stages which CMake doesn't support.
-        # Even if we could, it could change if other runners on the machine
-        # could run at the same time, so we drop it.
-        GIT_CLONE_PATH: "$CI_BUILDS_DIR\\cmake ci"
-
-.windows_ninja: &windows_ninja
-    extends: .windows_build
-
-    variables:
-        # Debug and RelWithDebinfo build types use the `/Zi` which results in
-        # uncacheable compiations.
-        # https://github.com/mozilla/sccache/issues/242
-        CMAKE_BUILD_TYPE: Release
-        CTEST_NO_WARNINGS_ALLOWED: 1
-
-.windows_vs2019_x64_ninja: &windows_vs2019_x64_ninja
-    extends: .windows_ninja
-
-    variables:
-        CMAKE_CONFIGURATION: windows_vs2019_x64_ninja
-        VCVARSALL: "${VS160COMNTOOLS}\\..\\..\\VC\\Auxiliary\\Build\\vcvarsall.bat"
-        VCVARSPLATFORM: "x64"
-        VCVARSVERSION: "14.26"
-
-.windows_vs2019_x64: &windows_vs2019_x64
-    extends: .windows
-
-    variables:
-        CMAKE_CONFIGURATION: windows_vs2019_x64
-        CMAKE_GENERATOR: "Visual Studio 16 2019"
-        CMAKE_GENERATOR_PLATFORM: "x64"
-        CMAKE_GENERATOR_TOOLSET: "v142,version=14.26"
-
-.linux_builder_tags: &linux_builder_tags
-    tags:
-        - build
-        - docker
-        - linux
-
-.linux_builder_tags_qt: &linux_builder_tags_qt
-    tags:
-        - build
-        - docker
-        - linux
-        - linux-3.17 # Needed to be able to load Fedora's Qt libraries.
-
-.linux_builder_tags_cuda: &linux_builder_tags_cuda
-    tags:
-        - cuda-rt
-        - docker
-        - linux
-
-.macos_builder_tags: &macos_builder_tags
-    tags:
-        - cmake # Since this is a bare runner, pin to a project.
-        - macos
-        - shell
-        - xcode-11.5
-        - nonconcurrent
-
-.macos_builder_ext_tags: &macos_builder_ext_tags
-    tags:
-        - cmake # Since this is a bare runner, pin to a project.
-        - macos
-        - shell
-        - xcode-11.5
-        - concurrent
-
-.windows_builder_tags: &windows_builder_tags
-    tags:
-        - cmake # Since this is a bare runner, pin to a project.
-        - windows
-        - shell
-        - vs2019
-        - msvc-19.25
-        - nonconcurrent
-
-.windows_builder_ext_tags: &windows_builder_ext_tags
-    tags:
-        - cmake # Since this is a bare runner, pin to a project.
-        - windows
-        - shell
-        - vs2019
-        - msvc-19.25
-        - concurrent
-
-.before_script_unix: &before_script_unix
-    - .gitlab/ci/cmake.sh
-    - .gitlab/ci/ninja.sh
-    - export PATH=$PWD/.gitlab:$PWD/.gitlab/cmake/bin:$PATH
-    - cmake --version
-    - ninja --version
-    # Download Qt on macOS
-    - "[ \"$( uname -s )\" = \"Darwin\" ] && cmake -P .gitlab/ci/download_qt.cmake"
-    - "[ \"$( uname -s )\" = \"Darwin\" ] && export CMAKE_PREFIX_PATH=$PWD/.gitlab/qt"
-
-.before_script_windows: &before_script_windows
-    - Invoke-Expression -Command .gitlab/ci/cmake.ps1
-    - Invoke-Expression -Command .gitlab/ci/ninja.ps1
-    - $pwdpath = $pwd.Path
-    - Set-Item -Force -Path "env:PATH" -Value "$pwdpath\.gitlab;$pwdpath\.gitlab\cmake\bin;$env:PATH"
-    - cmake --version
-    - ninja --version
-    - cmake -P .gitlab/ci/download_qt.cmake
-    - Set-Item -Force -Path "env:PATH" -Value "$pwdpath\.gitlab\qt\bin;$env:PATH"
-
-.cmake_build_unix: &cmake_build_unix
-    stage: build
-
-    script:
-        - *before_script_unix
-        - .gitlab/ci/sccache.sh
-        # Allow the server to already be running.
-        - "sccache --start-server || :"
-        - sccache --show-stats
-        - "$LAUNCHER ctest -VV -S .gitlab/ci/ctest_configure.cmake"
-        - "$LAUNCHER ctest -VV -S .gitlab/ci/ctest_build.cmake"
-        - sccache --show-stats
-
-    interruptible: true
-
-.cmake_build_release_linux: &cmake_build_release_linux
-    stage: build
-
-    script:
-        # Bootstrap.
-        - mkdir build/
-        - cp -v Utilities/Release/linux/x86_64/cache.txt build/CMakeCache.txt
-        # Make sccache available.
-        - .gitlab/ci/sccache.sh
-        - export PATH=$PWD/.gitlab:$PATH
-        # Append sccache settings to the cache.
-        - echo "CMAKE_C_COMPILER_LAUNCHER:STRING=sccache" >> build/CMakeCache.txt
-        - echo "CMAKE_CXX_COMPILER_LAUNCHER:STRING=sccache" >> build/CMakeCache.txt
-        # CI settings.
-        - echo "CMake_TEST_INSTALL:BOOL=OFF" >> build/CMakeCache.txt
-        - echo "CMAKE_INSTALL_PREFIX:PATH=$PWD/build/install" >> build/CMakeCache.txt
-        - echo "CMAKE_SKIP_INSTALL_ALL_DEPENDENCY:BOOL=ON" >> build/CMakeCache.txt
-        # Bootstrap
-        - cd build/
-        - "$LAUNCHER ../bootstrap --parallel=$(nproc) --docdir=doc/cmake"
-        # FIXME: When CTest can drive an external CMake for the build as well,
-        # use the scripts here.
-        - "$LAUNCHER make -j$(nproc)"
-        # NOTE: This regex matches that used in the release build.
-        - "$LAUNCHER bin/ctest --output-on-failure -j$(nproc) -R '^(CMake\\.|CMakeLib\\.|CMakeServerLib\\.|RunCMake\\.ctest_memcheck)'"
-        # Make a package.
-        - bin/cpack -G TGZ
-        - bin/cpack -G STGZ
-        - sccache --show-stats
-
-    interruptible: true
-
-.cmake_build_windows: &cmake_build_windows
-    stage: build
-
-    script:
-        - *before_script_windows
-        - Set-Item -Force -Path "env:PATH" -Value "$env:PATH;$env:SCCACHE_PATH"
-        - Invoke-Expression -Command .gitlab/ci/vcvarsall.ps1
-        - sccache --start-server
-        - sccache --show-stats
-        - ctest -VV -S .gitlab/ci/ctest_configure.cmake
-        - ctest -VV -S .gitlab/ci/ctest_build.cmake
-        - sccache --show-stats
-        - sccache --stop-server
-
-    interruptible: true
-
-.cmake_build_artifacts: &cmake_build_artifacts
-    artifacts:
-        expire_in: 1d
-        paths:
-            # XXX(globbing): Can be simplified with support from
-            # https://gitlab.com/gitlab-org/gitlab-runner/issues/4840
-            - build/CTestTestfile.cmake
-            - build/*/CTestTestfile.cmake
-            - build/*/*/CTestTestfile.cmake
-            - build/*/*/*/CTestTestfile.cmake
-            - build/*/*/*/*/CTestTestfile.cmake
-
-            # Allow CMake to find CMAKE_ROOT.
-            - build/CMakeFiles/CMakeSourceDir.txt
-
-            # Take the install tree.
-            - build/install/
-
-            # We need the main binaries.
-            - build/bin/
-            # The cache is needed for the installation test.
-            - build/CMakeCache.txt
-            # Test binaries. Eventually these might be better under
-            # `Source/Tests` or the like.
-            - build/Tests/EnforceConfig.cmake
-            - build/Tests/CMakeBuildTest.cmake
-            - build/Tests/CMakeBuildDoubleProjectTest.cmake
-            - build/Tests/CMake*/runcompilecommands
-            - build/Tests/CMake*/runcompilecommands.exe
-            - build/Tests/CMake*/test*
-            - build/Tests/CMake*/PseudoMemcheck/valgrind
-            - build/Tests/CMake*/PseudoMemcheck/purify
-            - build/Tests/CMake*/PseudoMemcheck/memcheck_fail
-            - build/Tests/CMake*/PseudoMemcheck/BC
-            - build/Tests/CMake*/PseudoMemcheck/valgrind.exe
-            - build/Tests/CMake*/PseudoMemcheck/purify.exe
-            - build/Tests/CMake*/PseudoMemcheck/memcheck_fail.exe
-            - build/Tests/CMake*/PseudoMemcheck/BC.exe
-            - build/Tests/CMake*/PseudoMemcheck/NoLog
-            - build/Tests/CMake*Lib/*LibTests
-            - build/Tests/CMake*Lib/*LibTests.exe
-            - build/Source/kwsys/cmsysTest*
-            - build/Source/kwsys/testConsoleBufChild.exe
-            - build/Utilities/cmcurl/curltest
-            - build/Utilities/cmcurl/curltest.exe
-            - build/Utilities/KWIML/test/kwiml_test
-            - build/Utilities/KWIML/test/kwiml_test.exe
-            - build/Source/kwsys/*cmsysTestDynload.*
-            - build/Source/kwsys/dynloaddir/cmsysTestDynloadImpl.dll
-            - build/Source/kwsys/dynloaddir/cmsysTestDynloadUse.dll
-
-            # Test directories.
-            - build/Tests/CTest*
-            - build/Tests/Find*
-            - build/Tests/Qt5*
-            - build/Tests/RunCMake/
-            - build/Tests/CMakeOnly/
-            - build/Tests/CMakeTests/
-
-            # CTest/CDash information.
-            - build/Testing/
-            - build/DartConfiguation.tcl
-            - build/CTestCustom.cmake
-
-.cmake_release_artifacts: &cmake_release_artifacts
-    artifacts:
-        expire_in: 5d
-        paths:
-            # Any packages made.
-            - build/cmake-*-Linux-x86_64.*
-
-.cmake_test_artifacts: &cmake_test_artifacts
-    artifacts:
-        expire_in: 1d
-        paths:
-            # Take the install tree.
-            - build/install/
-
-.cmake_test_unix: &cmake_test_unix
-    stage: test
-
-    script:
-        - *before_script_unix
-        - "$LAUNCHER ctest --output-on-failure -V -S .gitlab/ci/ctest_test.cmake"
-
-    interruptible: true
-
-.cmake_test_windows: &cmake_test_windows
-    stage: test
-
-    script:
-        - *before_script_windows
-        - Invoke-Expression -Command .gitlab/ci/vcvarsall.ps1
-        - ctest --output-on-failure -V -S .gitlab/ci/ctest_test.cmake
-
-    interruptible: true
-
-.cmake_test_linux_package: &cmake_test_linux_package
-    stage: test-ext
-
-    script:
-        - *before_script_unix
-        # Make the CMake package available.
-        - mkdir -p build/install
-        - tar -C build/install --strip-components=1 -xzf build/cmake-*-Linux-x86_64.tar.gz
-        - .gitlab/ci/sccache.sh
-        # Allow the server to already be running.
-        - "sccache --start-server || :"
-        - sccache --show-stats
-        - "$LAUNCHER build/install/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake"
-        - sccache --show-stats
-
-    interruptible: true
-
-.cmake_test_linux_external: &cmake_test_linux_external
-    stage: test-ext
-
-    script:
-        - *before_script_unix
-        - .gitlab/ci/sccache.sh
-        - sccache --start-server
-        - sccache --show-stats
-        - "$LAUNCHER build/install/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake"
-        - sccache --show-stats
-
-    interruptible: true
-
-.cmake_test_macos_external: &cmake_test_macos_external
-    stage: test-ext
-
-    script:
-        - *before_script_unix
-        - .gitlab/ci/sccache.sh
-        # Allow the server to already be running.
-        - "sccache --start-server || :"
-        - sccache --show-stats
-        - "$LAUNCHER build/install/CMake.app/Contents/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake"
-        - sccache --show-stats
-
-    interruptible: true
-
-.cmake_test_windows_external: &cmake_test_windows_external
-    stage: test-ext
-
-    script:
-        - build/install/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake
-
-    interruptible: true
+    # OS builds.
+    - local: .gitlab/os-unix.yml
+    - local: .gitlab/os-linux.yml
+    - local: .gitlab/os-macos.yml
+    - local: .gitlab/os-windows.yml
 
 stages:
     - build
     - test
     - test-ext
 
+# Lint builds
+
 build:debian10-iwyu:
     <<:
         - *debian10_iwyu
@@ -488,6 +37,8 @@
         - *linux_builder_tags_qt
     rules: *rules_settings
 
+# Linux builds
+
 build:centos6-release:
     <<:
         - *release_linux
@@ -549,6 +100,8 @@
     needs:
         - test:fedora31-ninja
 
+# macOS builds
+
 build:macos-ninja:
     <<:
         - *macos_ninja
@@ -599,6 +152,8 @@
     needs:
         - test:macos-ninja
 
+# Windows builds
+
 build:windows-vs2019-x64-ninja:
     <<:
         - *windows_vs2019_x64_ninja
diff --git a/.gitlab/artifacts.yml b/.gitlab/artifacts.yml
new file mode 100644
index 0000000..b25e4ff
--- /dev/null
+++ b/.gitlab/artifacts.yml
@@ -0,0 +1,79 @@
+# Lists of paths for artifacts of various stages.
+
+.cmake_build_artifacts: &cmake_build_artifacts
+    artifacts:
+        expire_in: 1d
+        paths:
+            # XXX(globbing): Can be simplified with support from
+            # https://gitlab.com/gitlab-org/gitlab-runner/issues/4840
+            - build/CTestTestfile.cmake
+            - build/*/CTestTestfile.cmake
+            - build/*/*/CTestTestfile.cmake
+            - build/*/*/*/CTestTestfile.cmake
+            - build/*/*/*/*/CTestTestfile.cmake
+
+            # Allow CMake to find CMAKE_ROOT.
+            - build/CMakeFiles/CMakeSourceDir.txt
+
+            # Take the install tree.
+            - build/install/
+
+            # We need the main binaries.
+            - build/bin/
+            # The cache is needed for the installation test.
+            - build/CMakeCache.txt
+            # Test binaries. Eventually these might be better under
+            # `Source/Tests` or the like.
+            - build/Tests/EnforceConfig.cmake
+            - build/Tests/CMakeBuildTest.cmake
+            - build/Tests/CMakeBuildDoubleProjectTest.cmake
+            - build/Tests/CMake*/runcompilecommands
+            - build/Tests/CMake*/runcompilecommands.exe
+            - build/Tests/CMake*/test*
+            - build/Tests/CMake*/PseudoMemcheck/valgrind
+            - build/Tests/CMake*/PseudoMemcheck/purify
+            - build/Tests/CMake*/PseudoMemcheck/memcheck_fail
+            - build/Tests/CMake*/PseudoMemcheck/BC
+            - build/Tests/CMake*/PseudoMemcheck/valgrind.exe
+            - build/Tests/CMake*/PseudoMemcheck/purify.exe
+            - build/Tests/CMake*/PseudoMemcheck/memcheck_fail.exe
+            - build/Tests/CMake*/PseudoMemcheck/BC.exe
+            - build/Tests/CMake*/PseudoMemcheck/NoLog
+            - build/Tests/CMake*Lib/*LibTests
+            - build/Tests/CMake*Lib/*LibTests.exe
+            - build/Source/kwsys/cmsysTest*
+            - build/Source/kwsys/testConsoleBufChild.exe
+            - build/Utilities/cmcurl/curltest
+            - build/Utilities/cmcurl/curltest.exe
+            - build/Utilities/KWIML/test/kwiml_test
+            - build/Utilities/KWIML/test/kwiml_test.exe
+            - build/Source/kwsys/*cmsysTestDynload.*
+            - build/Source/kwsys/dynloaddir/cmsysTestDynloadImpl.dll
+            - build/Source/kwsys/dynloaddir/cmsysTestDynloadUse.dll
+
+            # Test directories.
+            - build/Tests/CTest*
+            - build/Tests/Find*
+            - build/Tests/Qt5*
+            - build/Tests/RunCMake/
+            - build/Tests/CMakeOnly/
+            - build/Tests/CMakeTests/
+
+            # CTest/CDash information.
+            - build/Testing/
+            - build/DartConfiguation.tcl
+            - build/CTestCustom.cmake
+
+.cmake_release_artifacts: &cmake_release_artifacts
+    artifacts:
+        expire_in: 5d
+        paths:
+            # Any packages made.
+            - build/cmake-*-Linux-x86_64.*
+
+.cmake_test_artifacts: &cmake_test_artifacts
+    artifacts:
+        expire_in: 1d
+        paths:
+            # Take the install tree.
+            - build/install/
diff --git a/.gitlab/os-linux.yml b/.gitlab/os-linux.yml
new file mode 100644
index 0000000..7f7e506
--- /dev/null
+++ b/.gitlab/os-linux.yml
@@ -0,0 +1,180 @@
+# Linux-specific builder configurations and build commands
+
+## Base images
+
+### Release
+
+.release_linux: &release_linux
+    image: "kitware/cmake:build-linux-x86_64-deps-2020-04-02@sha256:77e9ab183f34680990db9da5945473e288f0d6556bce79ecc1589670d656e157"
+
+    variables:
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
+        LAUNCHER: "scl enable devtoolset-6 rh-python36 --"
+
+### Debian
+
+.debian10: &debian10
+    image: "kitware/cmake:ci-debian10-x86_64-2020-04-27"
+
+    variables:
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
+
+.debian10_iwyu: &debian10_iwyu
+    extends: .debian10
+
+    variables:
+        CMAKE_CONFIGURATION: debian10_iwyu
+        CTEST_NO_WARNINGS_ALLOWED: 1
+        CMake_SKIP_INSTALL: 1
+
+### Fedora
+
+.fedora31: &fedora31
+    image: "kitware/cmake:ci-fedora31-x86_64-2020-06-01"
+
+    variables:
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
+
+#### Lint builds
+
+.fedora31_tidy: &fedora31_tidy
+    extends: .fedora31
+
+    variables:
+        CMAKE_CONFIGURATION: fedora31_tidy
+        CTEST_NO_WARNINGS_ALLOWED: 1
+        CMake_SKIP_INSTALL: 1
+
+.fedora31_sphinx: &fedora31_sphinx
+    extends: .fedora31
+
+    variables:
+        CMAKE_CONFIGURATION: fedora31_sphinx
+        CTEST_NO_WARNINGS_ALLOWED: 1
+        CTEST_SOURCE_SUBDIRECTORY: "Utilities/Sphinx"
+        CMake_SKIP_INSTALL: 1
+
+#### Build and test
+
+.fedora31_ninja: &fedora31_ninja
+    extends: .fedora31
+
+    variables:
+        CMAKE_CONFIGURATION: fedora31_ninja
+        CTEST_NO_WARNINGS_ALLOWED: 1
+
+.fedora31_ninja_multi: &fedora31_ninja_multi
+    extends: .fedora31
+
+    variables:
+        CMAKE_CONFIGURATION: fedora31_ninja_multi
+        CTEST_NO_WARNINGS_ALLOWED: 1
+        CMAKE_GENERATOR: "Ninja Multi-Config"
+
+.fedora31_makefiles: &fedora31_makefiles
+    extends: .fedora31
+
+    variables:
+        CMAKE_CONFIGURATION: fedora31_makefiles
+        CTEST_NO_WARNINGS_ALLOWED: 1
+        CMAKE_GENERATOR: "Unix Makefiles"
+
+### CUDA builds
+
+.cuda10.2: &cuda
+    image: "kitware/cmake:ci-cuda10.2-x86_64-2020-06-11"
+
+    variables:
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
+        CTEST_LABELS: "CUDA"
+
+.cuda10.2_nvidia: &cuda10_2_nvidia
+    extends: .cuda10.2
+
+    variables:
+        CMAKE_CONFIGURATION: cuda10.2_nvidia
+        CTEST_NO_WARNINGS_ALLOWED: 1
+
+## Tags
+
+.linux_builder_tags: &linux_builder_tags
+    tags:
+        - build
+        - docker
+        - linux
+
+.linux_builder_tags_qt: &linux_builder_tags_qt
+    tags:
+        - build
+        - docker
+        - linux
+        - linux-3.17 # Needed to be able to load Fedora's Qt libraries.
+
+.linux_builder_tags_cuda: &linux_builder_tags_cuda
+    tags:
+        - cuda-rt
+        - docker
+        - linux
+
+## Linux-specific scripts
+
+.cmake_build_release_linux: &cmake_build_release_linux
+    stage: build
+
+    script:
+        # Bootstrap.
+        - mkdir build/
+        - cp -v Utilities/Release/linux/x86_64/cache.txt build/CMakeCache.txt
+        # Make sccache available.
+        - .gitlab/ci/sccache.sh
+        - export PATH=$PWD/.gitlab:$PATH
+        # Append sccache settings to the cache.
+        - echo "CMAKE_C_COMPILER_LAUNCHER:STRING=sccache" >> build/CMakeCache.txt
+        - echo "CMAKE_CXX_COMPILER_LAUNCHER:STRING=sccache" >> build/CMakeCache.txt
+        # CI settings.
+        - echo "CMake_TEST_INSTALL:BOOL=OFF" >> build/CMakeCache.txt
+        - echo "CMAKE_INSTALL_PREFIX:PATH=$PWD/build/install" >> build/CMakeCache.txt
+        - echo "CMAKE_SKIP_INSTALL_ALL_DEPENDENCY:BOOL=ON" >> build/CMakeCache.txt
+        # Bootstrap
+        - cd build/
+        - "$LAUNCHER ../bootstrap --parallel=$(nproc) --docdir=doc/cmake"
+        # FIXME: When CTest can drive an external CMake for the build as well,
+        # use the scripts here.
+        - "$LAUNCHER make -j$(nproc)"
+        # NOTE: This regex matches that used in the release build.
+        - "$LAUNCHER bin/ctest --output-on-failure -j$(nproc) -R '^(CMake\\.|CMakeLib\\.|CMakeServerLib\\.|RunCMake\\.ctest_memcheck)'"
+        # Make a package.
+        - bin/cpack -G TGZ
+        - bin/cpack -G STGZ
+        - sccache --show-stats
+
+    interruptible: true
+
+.cmake_test_linux_package: &cmake_test_linux_package
+    stage: test-ext
+
+    script:
+        - *before_script_unix
+        # Make the CMake package available.
+        - mkdir -p build/install
+        - tar -C build/install --strip-components=1 -xzf build/cmake-*-Linux-x86_64.tar.gz
+        - .gitlab/ci/sccache.sh
+        - sccache --start-server
+        - sccache --show-stats
+        - "$LAUNCHER build/install/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake"
+        - sccache --show-stats
+
+    interruptible: true
+
+.cmake_test_linux_external: &cmake_test_linux_external
+    stage: test-ext
+
+    script:
+        - *before_script_unix
+        - .gitlab/ci/sccache.sh
+        - sccache --start-server
+        - sccache --show-stats
+        - "$LAUNCHER build/install/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake"
+        - sccache --show-stats
+
+    interruptible: true
diff --git a/.gitlab/os-macos.yml b/.gitlab/os-macos.yml
new file mode 100644
index 0000000..b36de98
--- /dev/null
+++ b/.gitlab/os-macos.yml
@@ -0,0 +1,81 @@
+# macOS-specific builder configurations and build commands
+
+## Base configurations
+
+.macos: &macos
+    variables:
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci ext/$CI_CONCURRENT_ID"
+        # TODO: Factor this out so that each job selects the Xcode version to
+        # use so that different versions can be tested in a single pipeline.
+        DEVELOPER_DIR: "/Applications/Xcode-11.5.app/Contents/Developer"
+
+### Build and test
+
+.macos_build: &macos_build
+    extends: .macos
+
+    variables:
+        # Note that shell runners only support runners with a single
+        # concurrency level. We can't use `$CI_CONCURRENCY_ID` because this may
+        # change between the build and test stages which CMake doesn't support.
+        # Even if we could, it could change if other runners on the machine
+        # could run at the same time, so we drop it.
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
+
+.macos_ninja: &macos_ninja
+    extends: .macos_build
+
+    variables:
+        CMAKE_CONFIGURATION: macos_ninja
+        CTEST_NO_WARNINGS_ALLOWED: 1
+
+.macos_makefiles: &macos_makefiles
+    extends: .macos_build
+
+    variables:
+        CMAKE_CONFIGURATION: macos_makefiles
+        CTEST_NO_WARNINGS_ALLOWED: 1
+        CMAKE_GENERATOR: "Unix Makefiles"
+
+### External testing
+
+.macos_xcode: &macos_xcode
+    extends: .macos
+
+    variables:
+        CMAKE_CONFIGURATION: macos_xcode
+        CMAKE_GENERATOR: Xcode
+
+## Tags
+
+.macos_builder_tags: &macos_builder_tags
+    tags:
+        - cmake # Since this is a bare runner, pin to a project.
+        - macos
+        - shell
+        - xcode-11.5
+        - nonconcurrent
+
+.macos_builder_ext_tags: &macos_builder_ext_tags
+    tags:
+        - cmake # Since this is a bare runner, pin to a project.
+        - macos
+        - shell
+        - xcode-11.5
+        - concurrent
+
+## macOS-specific scripts
+
+.cmake_test_macos_external: &cmake_test_macos_external
+    stage: test-ext
+
+    script:
+        - *before_script_unix
+        - .gitlab/ci/sccache.sh
+        # Allow the server to already be running.
+        - "sccache --start-server || :"
+        - sccache --show-stats
+        - "$LAUNCHER build/install/CMake.app/Contents/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake"
+        - sccache --show-stats
+
+    interruptible: true
diff --git a/.gitlab/os-unix.yml b/.gitlab/os-unix.yml
new file mode 100644
index 0000000..902c428
--- /dev/null
+++ b/.gitlab/os-unix.yml
@@ -0,0 +1,35 @@
+# Unix-specific build commands
+
+.before_script_unix: &before_script_unix
+    - .gitlab/ci/cmake.sh
+    - .gitlab/ci/ninja.sh
+    - export PATH=$PWD/.gitlab:$PWD/.gitlab/cmake/bin:$PATH
+    - cmake --version
+    - ninja --version
+    # Download Qt on macOS
+    - "[ \"$( uname -s )\" = \"Darwin\" ] && cmake -P .gitlab/ci/download_qt.cmake"
+    - "[ \"$( uname -s )\" = \"Darwin\" ] && export CMAKE_PREFIX_PATH=$PWD/.gitlab/qt"
+
+.cmake_build_unix: &cmake_build_unix
+    stage: build
+
+    script:
+        - *before_script_unix
+        - .gitlab/ci/sccache.sh
+        # Allow the server to already be running.
+        - "sccache --start-server || :"
+        - sccache --show-stats
+        - "$LAUNCHER ctest -VV -S .gitlab/ci/ctest_configure.cmake"
+        - "$LAUNCHER ctest -VV -S .gitlab/ci/ctest_build.cmake"
+        - sccache --show-stats
+
+    interruptible: true
+
+.cmake_test_unix: &cmake_test_unix
+    stage: test
+
+    script:
+        - *before_script_unix
+        - "$LAUNCHER ctest --output-on-failure -V -S .gitlab/ci/ctest_test.cmake"
+
+    interruptible: true
diff --git a/.gitlab/os-windows.yml b/.gitlab/os-windows.yml
new file mode 100644
index 0000000..90d4685
--- /dev/null
+++ b/.gitlab/os-windows.yml
@@ -0,0 +1,116 @@
+# Windows-specific builder configurations and build commands
+
+## Base configurations
+
+.windows: &windows
+    variables:
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR\\cmake ci ext\\$CI_CONCURRENT_ID"
+
+### Build and test
+
+.windows_build: &windows_build
+    extends: .windows
+
+    variables:
+        # Note that shell runners only support runners with a single
+        # concurrency level. We can't use `$CI_CONCURRENCY_ID` because this may
+        # change between the build and test stages which CMake doesn't support.
+        # Even if we could, it could change if other runners on the machine
+        # could run at the same time, so we drop it.
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR\\cmake ci"
+
+.windows_ninja: &windows_ninja
+    extends: .windows_build
+
+    variables:
+        # Debug and RelWithDebinfo build types use the `/Zi` which results in
+        # uncacheable compiations.
+        # https://github.com/mozilla/sccache/issues/242
+        CMAKE_BUILD_TYPE: Release
+        CTEST_NO_WARNINGS_ALLOWED: 1
+
+.windows_vs2019_x64_ninja: &windows_vs2019_x64_ninja
+    extends: .windows_ninja
+
+    variables:
+        CMAKE_CONFIGURATION: windows_vs2019_x64_ninja
+        VCVARSALL: "${VS160COMNTOOLS}\\..\\..\\VC\\Auxiliary\\Build\\vcvarsall.bat"
+        VCVARSPLATFORM: "x64"
+        VCVARSVERSION: "14.26"
+
+### External testing
+
+.windows_vs2019_x64: &windows_vs2019_x64
+    extends: .windows
+
+    variables:
+        CMAKE_CONFIGURATION: windows_vs2019_x64
+        CMAKE_GENERATOR: "Visual Studio 16 2019"
+        CMAKE_GENERATOR_PLATFORM: "x64"
+        CMAKE_GENERATOR_TOOLSET: "v142,version=14.26"
+
+## Tags
+
+.windows_builder_tags: &windows_builder_tags
+    tags:
+        - cmake # Since this is a bare runner, pin to a project.
+        - windows
+        - shell
+        - vs2019
+        - msvc-19.25
+        - nonconcurrent
+
+.windows_builder_ext_tags: &windows_builder_ext_tags
+    tags:
+        - cmake # Since this is a bare runner, pin to a project.
+        - windows
+        - shell
+        - vs2019
+        - msvc-19.25
+        - concurrent
+
+## Windows-specific scripts
+
+.before_script_windows: &before_script_windows
+    - Invoke-Expression -Command .gitlab/ci/cmake.ps1
+    - Invoke-Expression -Command .gitlab/ci/ninja.ps1
+    - $pwdpath = $pwd.Path
+    - Set-Item -Force -Path "env:PATH" -Value "$pwdpath\.gitlab;$pwdpath\.gitlab\cmake\bin;$env:PATH"
+    - cmake --version
+    - ninja --version
+    - cmake -P .gitlab/ci/download_qt.cmake
+    - Set-Item -Force -Path "env:PATH" -Value "$pwdpath\.gitlab\qt\bin;$env:PATH"
+
+.cmake_build_windows: &cmake_build_windows
+    stage: build
+
+    script:
+        - *before_script_windows
+        - Set-Item -Force -Path "env:PATH" -Value "$env:PATH;$env:SCCACHE_PATH"
+        - Invoke-Expression -Command .gitlab/ci/vcvarsall.ps1
+        - sccache --start-server
+        - sccache --show-stats
+        - ctest -VV -S .gitlab/ci/ctest_configure.cmake
+        - ctest -VV -S .gitlab/ci/ctest_build.cmake
+        - sccache --show-stats
+        - sccache --stop-server
+
+    interruptible: true
+
+.cmake_test_windows: &cmake_test_windows
+    stage: test
+
+    script:
+        - *before_script_windows
+        - Invoke-Expression -Command .gitlab/ci/vcvarsall.ps1
+        - ctest --output-on-failure -V -S .gitlab/ci/ctest_test.cmake
+
+    interruptible: true
+
+.cmake_test_windows_external: &cmake_test_windows_external
+    stage: test-ext
+
+    script:
+        - build/install/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_test_external.cmake
+
+    interruptible: true
diff --git a/.gitlab/rules.yml b/.gitlab/rules.yml
new file mode 100644
index 0000000..6911e5e
--- /dev/null
+++ b/.gitlab/rules.yml
@@ -0,0 +1,16 @@
+# Rules for where jobs can run
+
+.manual_rules_settings: &manual_rules_settings
+    - if: '$CI_PROJECT_PATH == "cmake/cmake"'
+      when: delayed
+      start_in: 5 minutes
+    - if: '$CI_MERGE_REQUEST_ID'
+      when: manual
+    - when: never
+
+.rules_settings: &rules_settings
+    - if: '$CI_PROJECT_PATH == "cmake/cmake"'
+      when: always
+    - if: '$CI_MERGE_REQUEST_ID'
+      when: always
+    - when: never