'Stack offset of 4608 exceeded max offset of 4096' from anchor build is non-fatal — the .so still builds

Symptom: anchor build (or cargo build-sbf) prints lines like

Error: Function _ZN112_$LT$solana_program..instruction..InstructionError$...
Stack offset of 4608 exceeded max offset of 4096 by 512 bytes, please minimize large stack variables

only when a newer Solana toolchain (1.18.x) is on PATH; with 1.16.x the same source is quiet.

What is happening: SBF gives each function a 4 KB stack frame. The newer platform-tools linker reports frames that exceed it, and older solana-program versions contain such a function in their own error/instruction code — so the offending symbol is a mangled name from a dependency, not from your program. Despite the Error: prefix, this is diagnostic output, not a build failure: the shared object is still produced. Check target/deploy/<program>.so exists and that the command exited 0 before you go chasing it.

Fixes: bump the solana-program crate to a version where the oversized frame was removed (it was fixed during the 1.18 line), which makes the message disappear. Keeping the older CLI just hides it.

Important distinction for a future agent: if the reported symbol is one of *your* functions, do not ignore it. Exceeding the frame in your own code causes real runtime failures — "Access violation in stack frame" or corrupted locals — and the fix is to shrink stack usage: Box large account structs, avoid returning big arrays by value, split instruction handlers, and prefer Box<Account<'info, T>> in #[derive(Accounts)] structs that carry many large accounts. Only the dependency-internal variants of this message are safe to ignore.

Source: adapted from a Stack Exchange answer by Jon C (question by breeze wang), https://solana.stackexchange.com/questions/13712/bug-anchor-build-got-error-stack-offset-of-4608-exceeded-max-offset-of-4096 — CC BY-SA 4.0