support newer compilers

.github/workflows/build-and-release.yml

@@ -16,7 +16,7 @@ jobs:
 
           tag=${{ github.ref_name }}
 
-          g++ -O3 -DNDEBUG -DVERSION=$tag -flto -fno-rtti -std=gnu++17 -o "Release/trilangle-${tag}-ubuntu"
+          g++ -O3 -DNDEBUG -DVERSION=$tag -flto -fno-rtti -std=gnu++23 -o "Release/trilangle-${tag}-ubuntu"
           src/*.cpp
       - uses: actions/upload-artifact@v4
         with:
@@ -39,7 +39,7 @@ jobs:
 
           tag=${{ github.ref_name }}
 
-          clang++ -O3 -DNDEBUG -DVERSION=$tag -flto -fno-rtti -std=gnu++20 -target "$(clang -dumpmachine | sed -E
+          clang++ -O3 -DNDEBUG -DVERSION=$tag -flto -fno-rtti -std=gnu++23 -target "$(clang -dumpmachine | sed -E
           's/^\w+-/${{ matrix.arch }}-/')" -o "Release/trilangle-${tag}-macos-${{ matrix.arch }}" src/*.cpp
       - uses: actions/upload-artifact@v4
         with:

clitest.sh

@@ -4,7 +4,7 @@ set -ex
 
 # Some of the examples (particularly the Qdeql truth machine) run very slowly
 # if I/O buffering is enabled.
-g++ -Og -DNO_BUFFER -std=gnu++17 src/*.cpp -o trilangle
+g++ -Og -DNO_BUFFER -std=gnu++23 src/*.cpp -o trilangle
 
 for script in tests/cli/*/index.sh
 do

src/compat.hh

@@ -15,6 +15,7 @@
 
 #if __has_include(<stdfloat>)
 #include <stdfloat>
+#define _INCLUDED_STDFLOAT
 #endif
 
 #if __has_include(<version>)
@@ -44,17 +45,19 @@ constexpr int EX_NOINPUT = 66;
 #endif
 
 
-#ifdef __STDCPP_FLOAT16_T__
+#if defined(_INCLUDED_STDFLOAT) && defined(__STDCPP_FLOAT16_T__)
 // The smallest supported float type.
 typedef std::float16_t small_float;
-#elif defined(__STDCPP_BFLOAT16_T__)
+#elif defined(_INCLUDED_STDFLOAT) && defined(__STDCPP_BFLOAT16_T__)
 // The smallest supported float type.
 typedef std::bfloat16_t small_float;
 #else
 // The smallest supported float type.
 typedef float small_float;
 #endif
 
+#undef _INCLUDED_STDFLOAT
+
 
 #if !defined(__GNUC__) && defined(_MSC_VER)
 // 1 if the compiler is really MSVC, and not clang pretending to be MSVC. 0 for clang and GCC.