Update documentation about C++ version change

Author: spnda

README.md

@@ -7,9 +7,9 @@
 [![Documentation Status](https://readthedocs.org/projects/fastgltf/badge/?version=latest)](https://fastgltf.readthedocs.io/latest/?badge=latest)
 
 
-**fastgltf** is a speed and usability focused glTF 2.0 library written in modern C++17 with minimal dependencies.
+**fastgltf** is a speed and usability focused glTF 2.0 library written in modern C++20 with minimal dependencies.
 It uses SIMD in various areas to decrease the time the application spends parsing and loading glTF data.
-By taking advantage of modern C++17 (and optionally C++20) it also provides easy and safe access to the properties and data.
+By taking advantage of modern C++20 it also provides easy and safe access to the properties and data.
 It is also available as a C++20 [named module](https://en.cppreference.com/w/cpp/language/modules).
 
 The library supports the entirety of glTF 2.0 specification, including many extensions.
@@ -19,6 +19,9 @@ including accessor tools, the ability to directly write to mapped GPU buffers, a
 
 To learn more about fastgltf, its features, performance and API you can read [the docs](https://fastgltf.readthedocs.io/).
 
+> [!NOTE]  
+> For C++17 compatibility, please use v0.9.x. Later versions require C++20.
+
 ## Examples and real-world usage
 
 You can find some examples in the `examples/` directory of this repository on how to use fastgltf in a 3D renderer to load glTF files.

docs/index.rst

@@ -1,15 +1,18 @@
 fastgltf
 ========
 
-**fastgltf** is a speed and usability focused glTF 2.0 library written in modern C++17 with minimal dependencies.
+**fastgltf** is a speed and usability focused glTF 2.0 library written in modern C++20 with minimal dependencies.
 It uses SIMD in various areas to decrease the time the application spends parsing and loading glTF data.
-By taking advantage of modern C++17 (and optionally C++20) it also provides easy and safe access to the properties and data.
+By taking advantage of modern C++20 it also provides easy and safe access to the properties and data.
+It is also available as a C++20 `named module <https://en.cppreference.com/w/cpp/language/modules>`_.
 
 The library supports the entirety of glTF 2.0 specification, including many extensions.
 By default, fastgltf will only do the absolute minimum to work with a glTF model.
 However, it brings many additional features to ease working with the data,
 including accessor tools, the ability to directly write to mapped GPU buffers, and decomposing transform matrices.
 
+.. note::
+   For C++17 compatibility, please use v0.9.x. Later versions require C++20.
 
 Indices and tables
 ------------------

docs/options.rst

@@ -40,13 +40,6 @@ This allocator allocates fixed-size blocks of memory as needed and divides them
 All of this functionality can be disabled using this flag.
 All types will then be normal ``std`` containers and use standard heap allocation with new and malloc.
 
-``FASTGLTF_COMPILE_AS_CPP20``
------------------------------
-
-This ``BOOL`` option controls the C++ standard the library is compiled as. When ``NO`` fastgltf is always compiled as C++17.
-When ``YES`` fastgltf is compiled as C++20, including the tests. This might allow the compiler to perform certain optimisations,
-since fastgltf then uses some specialized stdlib functions instead.
-
 ``FASTGLTF_ENABLE_CPP_MODULES``
 -------------------------------
 

docs/overview.rst

@@ -4,16 +4,18 @@ Overview
 
 .. contents:: Table of Contents
 
-**fastgltf** is a speed and usability focused glTF 2.0 library written in modern C++17 with minimal dependencies.
+**fastgltf** is a speed and usability focused glTF 2.0 library written in modern C++20 with minimal dependencies.
 It uses SIMD in various areas to decrease the time the application spends parsing and loading glTF data.
-By taking advantage of modern C++17 (and optionally C++20) it also provides easy and safe access to the properties and data.
+By taking advantage of modern C++20 it also provides easy and safe access to the properties and data.
 It is also available as a C++20 `named module <https://en.cppreference.com/w/cpp/language/modules>`_.
 
 The library supports the entirety of glTF 2.0 specification, including many extensions.
 By default, **fastgltf** will only do the absolute minimum to work with a glTF model.
 However, it brings many additional features to ease working with the data,
 including accessor tools, the ability to directly write to mapped GPU buffers, and decomposing transform matrices.
 
+.. note::
+   For C++17 compatibility, please use v0.9.x. Later versions require C++20.
 
 .. _why:
 
@@ -110,7 +112,7 @@ Usage
 .. _vcpkg: https://github.com/microsoft/vcpkg
 .. _conan: https://conan.io/
 
-**fastgltf** is a pure C++17 library and only depends on simdjson.
+**fastgltf** is a C++20 library and only depends on simdjson.
 By using the included CMake 3.11 script, simdjson is automatically downloaded while configuring by default.
 The library is tested on GCC 9, GCC 10, Clang 13, and MSVC 14 (Visual Studio 2022) using CI.
 **fastgltf** is also available from vcpkg_ and conan_.