__BUILTIN_TYPES_COMPATIBLE_P(3)

💖 __builtin_types_compatible_p(3) — GNU extension to check equivalent types 💖

okay bestie, welcome to the Library Functions Manual — today’s main character is __builtin_types_compatible_p(3), and it’s literally here to check if two types are equivalent. no cap. 💅

---

✨ NAME ✨

__builtin_types_compatible_p — the GNU extension that checks whether two types are equivalent. 🫶

---

🌸 SYNOPSIS 🌸

call it like this, bestie:

int
__builtin_types_compatible_p(type_a, type_b);

---

🦋 DESCRIPTION 🦋

__builtin_types_compatible_p() is a GNU extension for determining whether two types are equivalent. If type_a is equivalent to type_b, you get the value 1. Otherwise, __builtin_types_compatible_p() returns 0. that’s the whole vibe. ✨

The following remarks should be taken into account — think of them as the receipts you gotta keep in mind:

1. The architecture-specific size of the two types does not have an impact on the result. For example, sizeof(char *) and sizeof(int) result the same value on i386, but the types naturally are not equivalent. 😭
2. Type qualifiers are ignored. The function returns the same value for long and const long. 💖
3. The amount of pointer indirection affects the result. For example, double * is not equivalent to double **. 🔥
4. Two types defined with typedef are equivalent if and only if their underlying types are equivalent. 👑
5. The enum type is a special case in that two enum types are not considered equivalent. 💀

---

🎀 EXAMPLES 🎀

The following example combines __builtin_types_compatible_p() and the typeof(3) construct:

             #define __COMPARE_TYPES(v, t)      \
                      __builtin_types_compatible_p(__typeof__(v), t)

             ...

             if (__COMPARE_TYPES(p, double) != 0)
                     err(EX_DATAERR, "invalid type");

---

🌈 SEE ALSO 🌈

go give these a lil scroll too, bestie:

• gcc(1)
• __builtin_constant_p(3)
• typeof(3)

---

⭐ CAVEATS ⭐

Caveat, fr fr: This is a non-standard, compiler-specific extension. 💅

---

Debian • December 21, 2010 • signing off on __builtin_types_compatible_p(3) — mwah, bestie 💖🫶