🐛 [sizeof] Wknd to support GCC >= 10

Problem:
- GCC >=10 doesn't compile with `array[0]` trick to make SML as small as possible.

Solution:
- Remove the zero sized array trick for GCC >= 10.
- Disable sizeof verifcation for GCC >= 10.

Note:
- Another solution has to be considered/implemented.

include/boost/sml.hpp

@@ -36,7 +36,11 @@
 #define __BOOST_SML_UNUSED __attribute__((unused))
 #define __BOOST_SML_VT_INIT \
   {}
+#if (__GNUC__ < 10)
 #define __BOOST_SML_ZERO_SIZE_ARRAY(...) __VA_ARGS__ _[0]
+#else
+#define __BOOST_SML_ZERO_SIZE_ARRAY(...)
+#endif
 #define __BOOST_SML_ZERO_SIZE_ARRAY_CREATE(...) __VA_ARGS__ ? __VA_ARGS__ : 1
 #define __BOOST_SML_TEMPLATE_KEYWORD template
 #pragma GCC diagnostic push

test/ft/sizeof.cpp

@@ -206,7 +206,9 @@ test sm_sizeof_no_capture = [] {
       // clang-format on
     }
   };
+#if defined(__clang__) or (__GNUC__ < 10)
   static_expect(1 /*current_state=1*/ == sizeof(sml::sm<no_capture_transition>));
+#endif
 };
 
 test sm_sizeof_more_than_256_transitions = [] {
@@ -476,6 +478,8 @@ test sm_sizeof_more_than_256_transitions = [] {
       // clang-format on
     }
   };
+#if defined(__clang__) or (__GNUC__ < 10)
   static_expect(2 /*current_state=2*/ == sizeof(sml::sm<c>));
+#endif
 };
 #endif

tools/pph.sh

@@ -37,7 +37,11 @@ pph() {
   echo "#endif"
   echo "#define __BOOST_SML_UNUSED __attribute__((unused))"
   echo "#define __BOOST_SML_VT_INIT {}"
+  echo "#if (__GNUC__ < 10)"
   echo "#define __BOOST_SML_ZERO_SIZE_ARRAY(...) __VA_ARGS__ _[0]"
+  echo "#else"
+  echo "#define __BOOST_SML_ZERO_SIZE_ARRAY(...)"
+  echo "#endif"
   echo "#define __BOOST_SML_ZERO_SIZE_ARRAY_CREATE(...) __VA_ARGS__ ? __VA_ARGS__ : 1"
   echo "#define __BOOST_SML_TEMPLATE_KEYWORD template"
   echo "#pragma GCC diagnostic push"