Revert "Revert "Merge pull request #18403 from lrusak/cpp17""

This reverts commit bd6818f1975ef4665d2319b482460f64aa4ae277.

This also includes a fix for the following:

    CLog: fix SPDLOG_LEVEL_NAMES to allow compiling

    Otherwise the following error occurs:

    xbmc/utils/log.h:12:89: error: ‘constexpr fmt::v8::basic_string_view<Char>::basic_string_view(const Char*) [with Char = char]’ called in a constant expression
       12 | #define SPDLOG_LEVEL_NAMES {"TRACE", "DEBUG", "INFO", "WARNING", "ERROR", "FATAL", "OFF"};
          |                                                                                         ^
    In file included from /usr/include/fmt/format.h:44,
                     from xbmc/utils/StringUtils.h:37,
                     from xbmc/utils/log.h:19,
    /usr/include/fmt/core.h:460:3: note: ‘constexpr fmt::v8::basic_string_view<Char>::basic_string_view(const Char*) [with Char = char]’ is not usable as a ‘constexpr’ function because:
      460 |   basic_string_view(const Char* s) : data_(s) {
          |   ^~~~~~~~~~~~~~~~~
    /usr/include/fmt/core.h:460:3: error: member ‘fmt::v8::basic_string_view<char>::size_’ must be initialized by mem-initializer in ‘constexpr’ constructor
    /usr/include/fmt/core.h:439:10: note: declared here
      439 |   size_t size_;
          |          ^~~~~

5 files changed, 6 insertions, 6 deletions

diff --git a/docs/README.Fedora.md b/docs/README.Fedora.md
index 352010351e..dea6a49f26 100644
--- a/docs/README.Fedora.md
+++ b/docs/README.Fedora.md
@@ -61,7 +61,7 @@ git clone https://github.com/xbmc/xbmc kodi
 ## 3. Install the required packages
 If you get a `package not found` type of message with the below command, remove the offending package(s) from the install list and reissue the command. Take a note of the missing dependencies and, after a successful step completion, **[build the missing dependencies manually](README.Linux.md#31-build-missing-dependencies)**.
 
-**NOTE:** Kodi requires a compiler with C++14 support, i.e. gcc >= 4.9 or clang >= 3.4
+**NOTE:** Kodi requires a compiler with C++17 support, i.e. gcc >= 7 or clang >= 5
 
 Install build dependencies:
 ```
diff --git a/docs/README.FreeBSD.md b/docs/README.FreeBSD.md
index 53a689d46d..8424cc1aa6 100644
--- a/docs/README.FreeBSD.md
+++ b/docs/README.FreeBSD.md
@@ -72,7 +72,7 @@ git clone https://github.com/xbmc/xbmc kodi
 ## 3. Install the required packages
 If you get a `package not found` type of message with the below command, remove the offending package(s) from the install list and reissue the command. Take a note of the missing dependencies and, after a successful step completion, **[build the missing dependencies manually](#31-build-missing-dependencies)**.
 
-**NOTE:** Kodi requires a compiler with C++14 support, i.e. gcc >= 4.9 or clang >= 3.4
+**NOTE:** Kodi requires a compiler with C++17 support, i.e. gcc >= 7 or clang >= 5
 
 Install build dependencies:
 ```
diff --git a/docs/README.Linux.md b/docs/README.Linux.md
index a0016cfbfb..9c9449f8fa 100644
--- a/docs/README.Linux.md
+++ b/docs/README.Linux.md
@@ -72,9 +72,9 @@ git clone https://github.com/xbmc/xbmc kodi
 ## 3. Install the required packages
 The following is the list of packages that are used to build Kodi on Debian/Ubuntu (with all supported external libraries enabled).
 
-**NOTE:** Kodi requires a compiler with C++14 support, i.e. gcc >= 4.9 or clang >= 3.4
+**NOTE:** Kodi requires a compiler with C++17 support, i.e. gcc >= 7 or clang >= 5
 
-* autoconf, automake, autopoint, gettext, autotools-dev, cmake, curl, default-jre | openjdk-6-jre | openjdk-7-jre, gawk, gcc (>= 4.9) | gcc-4.9, g++ (>= 4.9) | g++-4.9, cpp (>= 4.9) | cpp-4.9, flatbuffers, gdc, gperf, libasound2-dev | libasound-dev, libass-dev (>= 0.9.8), libavahi-client-dev, libavahi-common-dev, libbluetooth-dev, libbluray-dev, libbz2-dev, libcdio-dev, libcec4-dev | libcec-dev, libp8-platform-dev, libcrossguid-dev, libcurl4-openssl-dev | libcurl4-gnutls-dev | libcurl-dev, libcwiid-dev, libdbus-1-dev, libegl1-mesa-dev, libenca-dev, libflac-dev, libfontconfig-dev, libfmt3-dev | libfmt-dev, libfreetype6-dev, libfribidi-dev, libfstrcmp-dev, libgcrypt-dev, libgif-dev (>= 5.0.5), libgles2-mesa-dev [armel] | libgl1-mesa-dev | libgl-dev, libglew-dev, libglu1-mesa-dev | libglu-dev, libgnutls-dev | libgnutls28-dev, libgpg-error-dev, libgtest-dev, libiso9660-dev, libjpeg-dev, liblcms2-dev, liblirc-dev, libltdl-dev, liblzo2-dev, libmicrohttpd-dev, libmysqlclient-dev, libnfs-dev, libogg-dev, libomxil-bellagio-dev [armel], libpcre3-dev, libplist-dev, libpng12-dev | libpng-dev, libpulse-dev, libshairplay-dev, libsmbclient-dev, libspdlog-dev, libsqlite3-dev, libssl-dev, libtag1-dev (>= 1.8) | libtag1x8, libtiff5-dev | libtiff-dev | libtiff4-dev, libtinyxml-dev, libtool, libudev-dev, libunistring-dev, libva-dev, libvdpau-dev, libvorbis-dev, libxkbcommon-dev, libxmu-dev, libxrandr-dev, libxslt1-dev | libxslt-dev, libxt-dev, waylandpp-dev | netcat, wayland-protocols | wipe, lsb-release, meson (>= 0.47.0), nasm (>= 2.14), ninja-build, python3-dev, python3-pil | python-imaging, python-support | python3-minimal, rapidjson-dev, swig, unzip, uuid-dev, zip, zlib1g-dev
+* autoconf, automake, autopoint, gettext, autotools-dev, cmake, curl, default-jre | openjdk-6-jre | openjdk-7-jre, gawk, gcc (>= 7) | gcc-7, g++ (>= 7) | g++-7, cpp (>= 7) | cpp-7, flatbuffers, gdc, gperf, libasound2-dev | libasound-dev, libass-dev (>= 0.9.8), libavahi-client-dev, libavahi-common-dev, libbluetooth-dev, libbluray-dev, libbz2-dev, libcdio-dev, libcec4-dev | libcec-dev, libp8-platform-dev, libcrossguid-dev, libcurl4-openssl-dev | libcurl4-gnutls-dev | libcurl-dev, libcwiid-dev, libdbus-1-dev, libegl1-mesa-dev, libenca-dev, libflac-dev, libfontconfig-dev, libfmt3-dev | libfmt-dev, libfreetype6-dev, libfribidi-dev, libfstrcmp-dev, libgcrypt-dev, libgif-dev (>= 5.0.5), libgles2-mesa-dev [armel] | libgl1-mesa-dev | libgl-dev, libglew-dev, libglu1-mesa-dev | libglu-dev, libgnutls-dev | libgnutls28-dev, libgpg-error-dev, libgtest-dev, libiso9660-dev, libjpeg-dev, liblcms2-dev, liblirc-dev, libltdl-dev, liblzo2-dev, libmicrohttpd-dev, libmysqlclient-dev, libnfs-dev, libogg-dev, libomxil-bellagio-dev [armel], libpcre3-dev, libplist-dev, libpng12-dev | libpng-dev, libpulse-dev, libshairplay-dev, libsmbclient-dev, libspdlog-dev, libsqlite3-dev, libssl-dev, libtag1-dev (>= 1.8) | libtag1x8, libtiff5-dev | libtiff-dev | libtiff4-dev, libtinyxml-dev, libtool, libudev-dev, libunistring-dev, libva-dev, libvdpau-dev, libvorbis-dev, libxkbcommon-dev, libxmu-dev, libxrandr-dev, libxslt1-dev | libxslt-dev, libxt-dev, waylandpp-dev | netcat, wayland-protocols | wipe, lsb-release, meson (>= 0.47.0), nasm (>= 2.14), ninja-build, python3-dev, python3-pil | python-imaging, python-support | python3-minimal, rapidjson-dev, swig, unzip, uuid-dev, zip, zlib1g-dev
 
 ### 3.1. Build missing dependencies
 Some packages may be missing or outdated in older distributions. Notably `crossguid`, `libfmt`, `libspdlog`, `waylandpp`, `wayland-protocols`, etc. are known to be outdated or missing. Fortunately there is an easy way to build individual dependencies with **[Kodi's unified depends build system](../tools/depends/README.md)**.
diff --git a/docs/README.Ubuntu.md b/docs/README.Ubuntu.md
index e7e4e94674..3990483d12 100644
--- a/docs/README.Ubuntu.md
+++ b/docs/README.Ubuntu.md
@@ -112,7 +112,7 @@ sudo apt install distcc
 ### 3.2. Get build dependencies manually
 If you get a `package not found` type of message with the below command, remove the offending package(s) from the install list and reissue the command. Take a note of the missing dependencies and, after a successful step completion, **[build the missing dependencies manually](README.Linux.md#31-build-missing-dependencies)**.
 
-**NOTE:** Kodi requires a compiler with C++14 support, i.e. gcc >= 4.9 or clang >= 3.4
+**NOTE:** Kodi requires a compiler with C++17 support, i.e. gcc >= 7 or clang >= 5
 
 Install build dependencies manually:
 ```
diff --git a/docs/README.openSUSE.md b/docs/README.openSUSE.md
index f33975918b..98e8182fce 100644
--- a/docs/README.openSUSE.md
+++ b/docs/README.openSUSE.md
@@ -72,7 +72,7 @@ sudo zypper ref
 
 If you get a `package not found` type of message with the below command, remove the offending package(s) from the install list and reissue the command. Take a note of the missing dependencies and, after a successful step completion, **[build the missing dependencies manually](#31-build-missing-dependencies)**.
 
-**NOTE:** Kodi requires a compiler with C++14 support, i.e. gcc >= 4.9 or clang >= 3.4
+**NOTE:** Kodi requires a compiler with C++17 support, i.e. gcc >= 7 or clang >= 5
 
 Install build dependencies:
 ```