There Is Life Before Main in Rust
Disclosures
🧠 This post is 100% human-written. Claude was used for feedback and to assist with the linker symbol diagram. Cursor was used for feedback and to ensure examples were compilable.
The author of this post is deeply interested in the topic of life-before-main: he is the author of the ctor crate, and the creator of the linktime project that we’ll be using in the examples below.
Deriving a Bit-Twiddling Hack: Signed Integer Overflow
As a thin layer on top of assembly language, C’s integer arithmetic APIs have always been minimal, effectively just mapping the underlying assembly opcodes to the C arithmetic operators. In addition, while unsigned arithmetic can safely overflow in C, signed arithmetic overflow is considered undefined behaviour, and UB can end up in heartache for C developers.