static_assert(9)

💅 static_assert(9) — like, the kernel API manual, bestie

okay so picture this: it's Kernel API Manual o'clock and we're talking about static_assert(9). no cap, she's that girl.

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✨ NAME ✨

static_assert — check an integer constant expression at build time 🛠️✨

like… she checks ur math before the code ever even runs. queen behavior.

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🎀 SYNOPSIS 🎀

static_assert (expr , ... );

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🌸 ARGUMENTS 🌸

• expr — the expression to be checked 👀 that's the whole vibe. this is the thing getting vibe-checked at build time.
• ... — variable arguments 🫶 yes bestie, the varargs are just there, doing their little varargs thing.

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🦋 DESCRIPTION 🦋

okay so static_assert is literally a wrapper for the C11 _Static_assert, but with a lil macro magic sprinkled on top ✨ — the magic exists so the message is optional, and when you don't give one it defaults to the stringification of the tested expression. cute, right? 💅

now, contrary to BUILD_BUG_ON, static_assert can be used at global scope 🌍 — which, slay — but it requires the expression to be an integer constant expression. and i cannot stress this enough: it is not enough that __builtin_constant_p is true for expr. like, that is not the bar. the bar is an integer constant expression. periodt. 💀

also note the flip, because this is the part that gets people 🙈: BUILD_BUG_ON fails the build if the condition is true, while static_assert fails the build if the expression is false. opposite girls! mirrored icons! don't mix them up fr fr 😭

⚠️ warning bestie: get the polarity backwards and ur build will fail for the exact wrong reason. lowkey iconic, highkey painful.

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🔥 SEE ALSO 🔥

• Kernel file ./tools/include/linux/build_bug.h 📁
• BUILD_BUG_ON_MSG(9)
• BUILD_BUG_ON(9)
• BUILD_BUG(9)

go read those too, iykyk 🧚💜

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and that's the whole page, bestie 🎀🌸 — sourced straight from ./tools/include/linux, dated October 2026, with all my love and zero cap 🫶💖