Say C++17 everywhere the project describes itselfchore/cpp17-descriptions

The move to C++17 left a trail of older claims. The Runner's own
.clang-format still said c++20; the result is byte for byte the same under
either value. Premake and Xmake still compiled the library as C++20 and
the main library as C++14, which meant their CI jobs were not testing the
language the project promises. Both now use C++17 for every target.

The rest is text: the Meson pkg-config description claimed C++14, comments
in the CMake and Meson files explained requirements that no longer exist,
.clang-tidy gave C++14 as the reason for two exclusions, issue templates
asked for C++20 samples, and the example headers named -std=c++14 and
catch2-with-main. The release notes and the migration guide state the
C++17 minimum. Doxygen's brief called the project "Catch2's test API",
which presents it as Catch2. Meson declared only BSL-1.0; it now names both
licenses of the tree. The amalgamated files are regenerated.

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/ExtraTests/CMakeLists.txt b/tests/ExtraTests/CMakeLists.txt
index e6488650..232b86dc 100644
--- a/tests/ExtraTests/CMakeLists.txt
+++ b/tests/ExtraTests/CMakeLists.txt
@@ -430,7 +430,7 @@ add_executable(AmalgamatedTestCompilation
   ${CATCH_DIR}/extras/catch_amalgamated_third_party.hpp
 )
 target_include_directories(AmalgamatedTestCompilation PRIVATE ${CATCH_DIR}/extras)
-# The amalgamated files hold the runner, which needs C++20.
+# The amalgamated files hold the runner, which needs C++17.
 target_compile_features(AmalgamatedTestCompilation PRIVATE cxx_std_17)
 
 add_test(NAME AmalgamatedFileTest COMMAND AmalgamatedTestCompilation --no-history)