Bump required C++ standard to c++17

According to SciPy's Toolchain Roadmap [1], C++17 core features became
available in 2022. This was concluded based on minimum compiler versions
in `manylinux2014` images, AIX systems, FreeBSD systems, and Windows.
Note, some standard library features are not universally supported.

This commit does not move much code to C++17, just a couple of minor
improvements that I could easily change.

[1] https://docs.scipy.org/doc/scipy/dev/toolchain.html#c-language-standards

Author: QuLogic

doc/api/next_api_changes/development/27012-ES.rst

@@ -0,0 +1,7 @@
+Extensions require C++17
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Matplotlib now requires a compiler that supports C++17 in order to build its extensions.
+According to `SciPy's analysis
+<https://docs.scipy.org/doc/scipy/dev/toolchain.html#c-language-standards>`_, this
+should be available on all supported platforms.

doc/devel/dependencies.rst

@@ -233,7 +233,7 @@ in your target environment manually:
 C++ compiler
 ------------
 
-Matplotlib requires a C++ compiler that supports C++11, and each platform has a
+Matplotlib requires a C++ compiler that supports C++17, and each platform has a
 development environment that must be installed before a compiler can be installed.
 
 .. tab-set::
@@ -277,18 +277,18 @@ Xcode, VS Code or Linux package manager. Choose **one** compiler from this list:
      - platforms
      - notes
    * - GCC
-     - **4.8.1**
+     - **7.2**
      - Linux, macOS, Windows
-     - `gcc 4.8.1 <https://gcc.gnu.org/projects/cxx-status.html#cxx11>`_,
+     - `gcc 7.2 <https://gcc.gnu.org/projects/cxx-status.html#cxx17>`_,
        `GCC: Binaries <https://gcc.gnu.org/install/binaries.html>`_,
    * - Clang (LLVM)
-     - **3.3**
+     - **5**
      - Linux, macOS
-     - `clang 3.3 <https://clang.llvm.org/cxx_status.html>`_, `LLVM <https://releases.llvm.org/download.html>`_
+     - `clang 5 <https://clang.llvm.org/cxx_status.html>`_, `LLVM <https://releases.llvm.org/download.html>`_
    * - MSVC++
-     - **14.0**
+     - **16.0**
      - Windows
-     - `Visual Studio 2015 C++ <https://docs.microsoft.com/en-us/cpp/overview/visual-cpp-language-conformance?view=msvc-140>`_
+     - `Visual Studio 2019 C++ <https://docs.microsoft.com/en-us/cpp/overview/visual-cpp-language-conformance?view=msvc-160>`_
 
 
 

meson.build

@@ -10,7 +10,7 @@ project(
   meson_version: '>=1.1.0',
   default_options: [
     'b_lto=true',
-    'cpp_std=c++11',
+    'cpp_std=c++17',
     'auto_features=disabled',  # Force FreeType to avoid extra dependencies.
   ],
 )

src/_image_wrapper.cpp

@@ -10,41 +10,40 @@
  * */
 
 const char* image_resample__doc__ =
-"Resample input_array, blending it in-place into output_array, using an\n"
-"affine transformation.\n\n"
+R"""(Resample input_array, blending it in-place into output_array, using an affine transform.
 
-"Parameters\n"
-"----------\n"
-"input_array : 2-d or 3-d NumPy array of float, double or `numpy.uint8`\n"
-"    If 2-d, the image is grayscale.  If 3-d, the image must be of size\n"
-"    4 in the last dimension and represents RGBA data.\n\n"
+Parameters
+----------
+input_array : 2-d or 3-d NumPy array of float, double or `numpy.uint8`
+    If 2-d, the image is grayscale.  If 3-d, the image must be of size 4 in the last
+    dimension and represents RGBA data.
 
-"output_array : 2-d or 3-d NumPy array of float, double or `numpy.uint8`\n"
-"    The dtype and number of dimensions must match `input_array`.\n\n"
+output_array : 2-d or 3-d NumPy array of float, double or `numpy.uint8`
+    The dtype and number of dimensions must match `input_array`.
 
-"transform : matplotlib.transforms.Transform instance\n"
-"    The transformation from the input array to the output array.\n\n"
+transform : matplotlib.transforms.Transform instance
+    The transformation from the input array to the output array.
 
-"interpolation : int, default: NEAREST\n"
-"    The interpolation method.  Must be one of the following constants\n"
-"    defined in this module:\n\n"
+interpolation : int, default: NEAREST
+    The interpolation method.  Must be one of the following constants defined in this
+    module:
 
-"      NEAREST, BILINEAR, BICUBIC, SPLINE16, SPLINE36,\n"
-"      HANNING, HAMMING, HERMITE, KAISER, QUADRIC, CATROM, GAUSSIAN,\n"
-"      BESSEL, MITCHELL, SINC, LANCZOS, BLACKMAN\n\n"
+      NEAREST, BILINEAR, BICUBIC, SPLINE16, SPLINE36, HANNING, HAMMING, HERMITE, KAISER,
+      QUADRIC, CATROM, GAUSSIAN, BESSEL, MITCHELL, SINC, LANCZOS, BLACKMAN
 
-"resample : bool, optional\n"
-"    When `True`, use a full resampling method.  When `False`, only\n"
-"    resample when the output image is larger than the input image.\n\n"
+resample : bool, optional
+    When `True`, use a full resampling method.  When `False`, only resample when the
+    output image is larger than the input image.
 
-"alpha : float, default: 1\n"
-"    The transparency level, from 0 (transparent) to 1 (opaque).\n\n"
+alpha : float, default: 1
+    The transparency level, from 0 (transparent) to 1 (opaque).
 
-"norm : bool, default: False\n"
-"    Whether to norm the interpolation function.\n\n"
+norm : bool, default: False
+    Whether to norm the interpolation function.
 
-"radius: float, default: 1\n"
-"    The radius of the kernel, if method is SINC, LANCZOS or BLACKMAN.\n";
+radius: float, default: 1
+    The radius of the kernel, if method is SINC, LANCZOS or BLACKMAN.
+)""";
 
 
 static pybind11::array_t<double>