evilgcc.h

#pragma once

#ifndef __GNUC__
#    error This header only works in GCC
#endif

#ifdef __clang__
#    ifndef __ccls__
#        warning This header may not working in clang
#    endif
#endif

// https://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html
#define local_label __label__

// https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
#define scoped(f) __attribute__((cleanup(f)))

#ifndef __cplusplus
#    ifdef __ccls__
#        define defer(...)
#    else
#        define defer(name, ...)                                                                                       \
            __attribute__((always_inline)) inline void defer_##name(void *_) { __VA_ARGS__; };                         \
            struct {                                                                                                   \
            } __defer_##name scoped(defer_##name)
#    endif
#else
template <typename T> struct __defer__ {
    T func;
    ~__defer__() { func(); }
};
template <typename T> __defer__(T t)->__defer__<T>;

#    define defer(name, ...)                                                                                           \
        auto __defer_##name = __defer__ {                                                                              \
            [&]() { __VA_ARGS__; }                                                                                     \
        }
#endif

#define defer_(thing, fn) defer(thing, fn(thing))
#define defer_ref(thing, fn) defer(thing, fn(&thing))

#ifndef __cplusplus
#    ifndef __ccls__
#        define lam(ret, ...)                                                                                          \
            ({                                                                                                         \
                ret __fn__ __VA_ARGS__;                                                                                \
                __fn__;                                                                                                \
            })
#    else
#        define lam(...) (void *) 0
#    endif
#else
#    define lam(ret, ...) +[] __VA_ARGS__
#endif

#define lam0(...) lam(void, __VA_ARGS__)

// https://gcc.gnu.org/onlinedocs/gcc/Alignment.html
#define alignof __alignof__

#ifndef __cplusplus
#    ifndef static_assert
#        define static_assert _Static_assert
#    endif
#    ifndef thread_local
#        define thread_local __thread
#    endif
#    ifndef auto
#        define auto __auto_type
#    endif
#endif

#define DO_PRAGMA(x) _Pragma(#x)
#define TODO(x) DO_PRAGMA(message("TODO - " #x))