那就是constexpr修饰的函数，返回值不一定是编译期常量。#It is not a bug, it is a feature.# ...
null statements(plain semicolons) static_assertdeclarations typedefdeclarations andaliasdeclarations that do not define classes or enumerations using declarations using directives if the function is not a constructor, exactly onereturnstatement (until C++14) ...
+ if (TREE_CODE (string) == VIEW_CONVERT_EXPR) + string = TREE_OPERAND (string, 0); + cexpr_str cstr (string); + if (!cstr.type_check (tok->location)) + return error_mark_node; + const char *msg; + int len; + if (!cstr.extract (tok->location, msg, len)) + return e...