matplotlib
diff --git a/.appveyor.yml b/.appveyor.yml
@@ -70,7 +70,7 @@ install:
 test_script:
   # Now build the thing..
   - set LINK=/LIBPATH:%cd%\lib
-  - pip install -ve .
+  - pip install -v --no-build-isolation --config-settings=setup-args="--vsenv" --editable .[dev]
   # this should show no freetype dll...
   - set "DUMPBIN=%VS140COMNTOOLS%\..\..\VC\bin\dumpbin.exe"
   - '"%DUMPBIN%" /DEPENDENTS lib\matplotlib\ft2font*.pyd | findstr freetype.*.dll && exit /b 1 || exit /b 0'

diff --git a/.circleci/config.yml b/.circleci/config.yml
@@ -55,6 +55,7 @@ commands:
               graphviz \
               inkscape \
               lmodern \
+              ninja-build \
               optipng \
               texlive-fonts-recommended \
               texlive-latex-base \
@@ -97,6 +98,7 @@ commands:
       - run:
           name: Install Python dependencies
           command: |
+            python -m pip install --user meson-python pybind11
             python -m pip install --user \
                 numpy<< parameters.numpy_version >> \
                 -r requirements/doc/doc-requirements.txt
@@ -114,15 +116,13 @@ commands:
               version=${version#v}
               python -m pip install matplotlib==${version}
             else
-              python -m pip install --user -ve .
+              python -m pip install --user --verbose \
+                --no-build-isolation --editable .[dev]
             fi
       - save_cache:
-          key: build-deps-1
+          key: build-deps-2
           paths:
-            # FreeType 2.6.1 tarball.
-            - ~/.cache/matplotlib/0a3c7dfbda6da1e8fce29232e8e96d987ababbbf71ebc8c75659e4132c367014
-            # Qhull 2020.2 tarball.
-            - ~/.cache/matplotlib/b5c2d7eb833278881b952c8a52d20179eab87766b00b865000469a45c1838b7e
+            - subprojects/packagecache
 
   doc-build:
     steps:
@@ -218,8 +218,8 @@ jobs:
       - fonts-install
       - pip-install
 
-      - mpl-install
       - doc-deps-install
+      - mpl-install
 
       - doc-build
       - doc-show-errors-warnings

diff --git a/.flake8 b/.flake8
@@ -31,8 +31,6 @@ exclude =
     .eggs
 
 per-file-ignores =
-    setup.py: E402
-
     lib/matplotlib/__init__.py: E402, F401
     lib/matplotlib/_animation_data.py: E501
     lib/matplotlib/_api/__init__.py: F401

diff --git a/.github/workflows/cibuildwheel.yml b/.github/workflows/cibuildwheel.yml
@@ -91,16 +91,17 @@ jobs:
     runs-on: ${{ matrix.os }}
     env:
       CIBW_BEFORE_BUILD: >-
-        pip install certifi numpy>=1.25 &&
+        pip install numpy>=1.25 &&
         rm -rf {package}/build
       CIBW_BEFORE_BUILD_WINDOWS: >-
-        pip install certifi delvewheel numpy>=1.25 &&
+        pip install delvewheel numpy>=1.25 &&
         rm -rf {package}/build
       CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: >-
         delvewheel repair -w {dest_dir} {wheel}
       CIBW_AFTER_BUILD: >-
         twine check {wheel} &&
         python {package}/ci/check_wheel_licenses.py {wheel}
+      CIBW_CONFIG_SETTINGS: setup-args="--vsenv"
       CIBW_MANYLINUX_X86_64_IMAGE: manylinux2014
       CIBW_SKIP: "*-musllinux_aarch64"
       CIBW_TEST_COMMAND: >-
@@ -144,11 +145,11 @@ jobs:
           CIBW_ARCHS: ${{ matrix.cibw_archs }}
           # Remove this once NumPy with Python 3.12 wheels is not pre-release.
           CIBW_BEFORE_BUILD: >-
-            pip install certifi "pybind11>=2.6" "setuptools>=42" "setuptools_scm>=7" &&
+            pip install "meson-python>=0.13.1" ninja "pybind11>=2.6" "setuptools>=42" "setuptools_scm>=7" &&
             pip install --pre "numpy>=1.25" &&
             rm -rf {package}/build
           CIBW_BEFORE_BUILD_WINDOWS: >-
-            pip install certifi delvewheel "pybind11>=2.6" "setuptools>=42" "setuptools_scm>=7" &&
+            pip install delvewheel "meson-python>=0.13.1" ninja "pybind11>=2.6" "setuptools>=42" "setuptools_scm>=7" &&
             pip install --pre "numpy>=1.25" &&
             rm -rf {package}/build
           CIBW_ENVIRONMENT: PIP_NO_BUILD_ISOLATION=0

diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
@@ -41,9 +41,9 @@ jobs:
           # dependencies so we don't need another copy here.
           # https://github.com/jazzband/pip-tools/pull/1681
           python -m pip install --upgrade \
-            certifi contourpy cycler fonttools kiwisolver importlib_resources \
-            numpy packaging pillow pyparsing python-dateutil setuptools-scm \
-            pybind11
+            build contourpy cycler fonttools kiwisolver \
+            importlib_resources meson-python numpy packaging pillow pybind11 \
+            pyparsing python-dateutil setuptools-scm
           echo "CODEQL_PYTHON=$(which python)" >> $GITHUB_ENV
 
       - name: Initialize CodeQL
@@ -56,7 +56,7 @@ jobs:
         if: matrix.language == 'cpp'
         run: |
           mkdir ~/.cache/matplotlib
-          $CODEQL_PYTHON setup.py build
+          $CODEQL_PYTHON -m build
 
       - name: Perform CodeQL Analysis
         uses: github/codeql-action/analyze@v2
diff --git a/.github/workflows/cygwin.yml b/.github/workflows/cygwin.yml
@@ -174,8 +174,8 @@ jobs:
       - name: Install Python dependencies
         shell: bash.exe -eo pipefail -o igncr "{0}"
         run: |
-          python -m pip install --upgrade pip 'setuptools<60' wheel
-          python -m pip install kiwisolver 'numpy!=1.21.*' pillow importlib_resources
+          python -m pip install --upgrade pip setuptools wheel
+          python -m pip install kiwisolver 'numpy>=1.22,<1.26' pillow importlib_resources
           grep -v -F -e psutil requirements/testing/all.txt >requirements_test.txt
           python -m pip install meson-python pybind11
           export PATH="/usr/local/bin:$PATH"
@@ -203,20 +203,14 @@ jobs:
           AUTOCONF: /usr/bin/autoconf-2.69
           MAKEFLAGS: dw
         run: |
+          export PATH="/usr/local/bin:$PATH"
           ccache -s
           git describe
-          cat <<EOT >> mplsetup.cfg
-          [rc_options]
-          backend=Agg
-
-          [libs]
-          system_freetype = False
-          system_qhull = True
-          EOT
-          cat mplsetup.cfg
           # All dependencies must have been pre-installed, so that the minver
           # constraints are held.
-          python -m pip install --no-deps -ve .
+          python -m pip install --no-deps --no-build-isolation --verbose \
+            --config-settings=setup-args="-DrcParams-backend=Agg" \
+            --editable .[dev]
 
       - name: Find DLLs to rebase
         shell: bash.exe -eo pipefail -o igncr "{0}"

diff --git a/.github/workflows/mypy-stubtest.yml b/.github/workflows/mypy-stubtest.yml
@@ -22,7 +22,7 @@ jobs:
         run: |
           pip3 install -r requirements/testing/mypy.txt \
             -r requirements/testing/all.txt
-          pip3 install -e .
+          pip3 install .
 
       - name: Set up reviewdog
         run: |
@@ -38,6 +38,7 @@ jobs:
         run: |
           set -o pipefail
           MPLBACKEND=agg python tools/stubtest.py | \
+              sed -e "s!$pythonLocation/lib/python3.9/site-packages!lib!g" | \
               reviewdog \
                 -efm '%Eerror: %m' \
                 -efm '%CStub: in file %f:%l' \

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
@@ -56,7 +56,6 @@ jobs:
             pyside2-ver: '==5.15.1'  # oldest version with working Py3.9 wheel.
             pyside6-ver: '==6.0.0'
             delete-font-cache: true
-            no-build-isolation: true
           - os: ubuntu-20.04
             python-version: 3.9
             extra-requirements: '-r requirements/testing/extra.txt'
@@ -81,7 +80,6 @@ jobs:
             python-version: '3.12-dev'
             pyside6-ver: '!=6.5.1'
             pre: true
-            no-build-isolation: true
           - os: macos-latest
             python-version: 3.9
             # https://bugreports.qt.io/projects/PYSIDE/issues/PYSIDE-2346
@@ -131,6 +129,7 @@ jobs:
               libxcb-render-util0 \
               libxcb-xinerama0 \
               lmodern \
+              ninja-build \
               pkg-config \
               qtbase5-dev \
               texlive-fonts-recommended \
@@ -150,7 +149,7 @@ jobs:
           macOS)
             brew install ccache
             brew tap homebrew/cask-fonts
-            brew install font-noto-sans-cjk gobject-introspection gtk4
+            brew install font-noto-sans-cjk gobject-introspection gtk4 ninja
             ;;
           esac
 
@@ -205,17 +204,14 @@ jobs:
           fi
 
           # Install dependencies from PyPI.
+          # Preinstall build requirements to enable no-build-isolation builds.
           python -m pip install --upgrade $PRE \
             'contourpy>=1.0.1' cycler fonttools kiwisolver importlib_resources \
             numpy packaging pillow 'pyparsing!=3.1.0' python-dateutil setuptools-scm \
+            'meson-python>=0.13.1' 'pybind11>=2.6' \
             -r requirements/testing/all.txt \
             ${{ matrix.extra-requirements }}
 
-          # Preinstall pybind11 on no-build-isolation builds.
-          if [[ "${{ matrix.no-build-isolation }}" == 'true' ]]; then
-            python -m pip install 'pybind11>=2.6'
-          fi
-
           # Install optional dependencies from PyPI.
           # Sphinx is needed to run sphinxext tests
           python -m pip install --upgrade sphinx!=6.1.2
@@ -300,20 +296,9 @@ jobs:
             fi
           fi
 
-          cat <<EOT >> mplsetup.cfg
-          [rc_options]
-          backend=Agg
-          EOT
-
-          cat mplsetup.cfg
-
-          if [[ "${{ matrix.no-build-isolation }}" == 'true' ]]; then
-            # Minimum versions run does not use build isolation so that it
-            # builds against the pre-installed minver dependencies.
-            python -m pip install --no-deps --no-build-isolation -ve .
-          else
-            python -m pip install --no-deps -ve .
-          fi
+          python -m pip install --no-deps --no-build-isolation --verbose \
+            --config-settings=setup-args="-DrcParams-backend=Agg" \
+            --editable .[dev]
 
           if [[ "${{ runner.os }}" != 'macOS' ]]; then
             unset CPPFLAGS

diff --git a/.gitignore b/.gitignore
@@ -29,10 +29,10 @@
 
 # Python files #
 ################
-# setup.py working directory
+# meson-python working directory
 build
 
-# setup.py dist directory
+# meson-python/build frontend dist directory
 dist
 # Egg metadata
 *.egg-info
@@ -41,9 +41,9 @@ dist
 pip-wheel-metadata/*
 # tox testing tool
 .tox
-mplsetup.cfg
-# generated by setuptools_scm
-lib/matplotlib/_version.py
+# build subproject files
+subprojects/*/
+!subprojects/packagefiles/
 
 # OS generated files #
 ######################

diff --git a/azure-pipelines.yml b/azure-pipelines.yml
@@ -96,6 +96,7 @@ stages:
               cm-super \
               dvipng \
               ffmpeg \
+              fonts-freefont-otf \
               fonts-noto-cjk \
               fonts-wqy-zenhei \
               gdb \
@@ -105,23 +106,24 @@ stages:
               libcairo2 \
               libgirepository-1.0-1 \
               lmodern \
-              fonts-freefont-otf \
+              ninja-build \
               poppler-utils \
-              texlive-pictures \
               texlive-fonts-recommended \
               texlive-latex-base \
               texlive-latex-extra \
               texlive-latex-recommended \
               texlive-luatex \
+              texlive-pictures \
               texlive-xetex
             ;;
           darwin)
             brew install --cask xquartz
-            brew install pkg-config ffmpeg imagemagick mplayer ccache
+            brew install ccache ffmpeg imagemagick mplayer ninja pkg-config
             brew tap homebrew/cask-fonts
             brew install font-noto-sans-cjk-sc
             ;;
           win32)
+            choco install ninja
             ;;
           *)
             exit 1
@@ -131,12 +133,15 @@ stages:
 
       - bash: |
           python -m pip install --upgrade pip
+          python -m pip install --upgrade meson-python pybind11
           python -m pip install -r requirements/testing/all.txt -r requirements/testing/extra.txt ||
             [[ "$PYTHON_VERSION" = 'Pre' ]]
         displayName: 'Install dependencies with pip'
 
       - bash: |
-          python -m pip install -ve . ||
+          python -m pip install \
+            --no-build-isolation --config-settings=setup-args="--vsenv" \
+            --verbose --editable .[dev] ||
             [[ "$PYTHON_VERSION" = 'Pre' ]]
         displayName: "Install self"
 

diff --git a/doc/api/next_api_changes/development/26621-ES.rst b/doc/api/next_api_changes/development/26621-ES.rst
@@ -0,0 +1,46 @@
+Build system ported to Meson
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The build system of Matplotlib has been ported from setuptools to `meson-python
+<https://meson-python.readthedocs.io>`_ and `Meson <https://mesonbuild.com>`_.
+Consequently, there have been a few changes for development and packaging purposes.
+
+1. Installation by ``pip`` of packages with ``pyproject.toml`` use `build isolation
+   <https://pip.pypa.io/en/stable/reference/build-system/pyproject-toml/#build-isolation>`_
+   by default, which interferes with editable installation. Thus for developers using
+   editable installs, it is now necessary to pass the ``--no-build-isolation`` flag to
+   ``pip install``. This means that all build-time requirements must be available in the
+   environment for an editable install.
+2. Build configuration has moved from a custom :file:`mplsetup.cfg` (also configurable
+   via ``MPLSETUP`` environment variable) to Meson options. These may be specified using
+   `meson-python's build config settings
+   <https://meson-python.readthedocs.io/en/stable/how-to-guides/config-settings.html>`_
+   for ``setup-args``. See :file:`meson_options.txt` for all options. For example, a
+   :file:`mplsetup.cfg` containing the following::
+
+      [rc_options]
+      backend=Agg
+
+      [libs]
+      system_qhull = True
+
+   may be replaced by passing the following arguments to ``pip``::
+
+      --config-settings=setup-args="-DrcParams-backend=Agg" \
+      --config-settings=setup-args="-Dsystem-qhull=true"
+
+   Note that you must use ``pip`` >= 23.1 in order to pass more than one setting.
+3. Relatedly, Meson's `builtin options <https://mesonbuild.com/Builtin-options.html>`_
+   are now used instead of custom options, e.g., the LTO option is now ``b_lto``.
+4. On Windows, Meson activates a Visual Studio environment automatically. However, it
+   will not do so if another compiler is available. See `Meson's documentation
+   <https://mesonbuild.com/Builtin-options.html#details-for-vsenv>`_ if you wish to
+   change the priority of chosen compilers.
+5. Installation of test data was previously controlled by :file:`mplsetup.cfg`, but has
+   now been moved to Meson's install tags. To install test data, add the ``tests``
+   tag to the requested install (be sure to include the existing tags as below)::
+
+      --config-settings=install-args="--tags=data,python-runtime,runtime,tests"
+6. Checking typing stubs with ``stubtest`` does not work easily with editable install.
+   For the time being, we suggest using a normal (non-editable) install if you wish to
+   run ``stubtest``.
diff --git a/doc/devel/contribute.rst b/doc/devel/contribute.rst
@@ -266,7 +266,7 @@ A brief overview of the workflow is as follows.
 
 #. Install the local version of Matplotlib with::
 
-     python -m pip install -e .
+     python -m pip install --no-build-isolation --editable .[dev]
 
    See :ref:`installing_for_devs` for detailed instructions.
 
@@ -476,9 +476,8 @@ take particular care when adding new API:
 New modules and files: installation
 -----------------------------------
 
-* If you have added new files or directories, or reorganized existing
-  ones, make sure the new files are included in the match patterns in
-  in *package_data* in :file:`setupext.py`.
+* If you have added new files or directories, or reorganized existing ones, make sure the
+  new files are included in the :file:`meson.build` in the corresponding directories.
 * New modules *may* be typed inline or using parallel stub file like existing modules.
 
 C/C++ extensions