Clippy wrongly reports clippy::large_stack_arrays on static struct

[tokatoka]

Summary

Hello, I have a problem with clippy::large_stack_arrays lint.

Clippy reports clippy::large_stack_arrays on a public static mut struct defined like

/// The global `CmpLog` map for the current `LibAFL` run.
#[no_mangle]
pub static mut libafl_cmplog_map: CmpLogMap = CmpLogMap {
    headers: [CmpLogHeader {
        hits: 0,
        shape: 0,
        kind: 0,
    }; CMPLOG_MAP_W],
    vals: CmpLogVals {
        operands: [[CmpLogInstruction(0, 0); CMPLOG_MAP_H]; CMPLOG_MAP_W],
    },
};

and here's the short output from clippy

error: allocating a local array larger than 512000 bytes
   --> libafl_targets/src/cmplog.rs:165:19
    |
165 |         operands: [[CmpLogInstruction(0, 0); CMPLOG_MAP_H]; CMPLOG_MAP_W],

clippy suggests to put this on heap, but it is not possible because it's a static struct.

Thank you!

Lint Name

clippy::large_stack_arrays

Reproducer

1. Clone this repository: git clone https://github.com/AFLplusplus/LibAFL.git
2. Checkout to: git checkout b86314282907aa77d727e3bb9a1b03b75ad441c0
3. Run clippy: cargo +nightly clippy --all --all-features

Clippy reports

error: allocating a local array larger than 512000 bytes
   --> libafl_targets/src/cmplog.rs:165:19
    |
165 |         operands: [[CmpLogInstruction(0, 0); CMPLOG_MAP_H]; CMPLOG_MAP_W],
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
note: the lint level is defined here
   --> libafl_targets/src/lib.rs:7:9
    |
7   | #![deny(clippy::pedantic)]
    |         ^^^^^^^^^^^^^^^^
    = note: `#[deny(clippy::large_stack_arrays)]` implied by `#[deny(clippy::pedantic)]`
    = help: consider allocating on the heap with `vec![[CmpLogInstruction(0, 0); CMPLOG_MAP_H]; CMPLOG_MAP_W].into_boxed_slice()`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#large_stack_arrays

But, in our code, this is a pub static mutstruct (https://github.com/AFLplusplus/LibAFL/blob/main/libafl_targets/src/cmplog.rs#L158)

/// The global `CmpLog` map for the current `LibAFL` run.
#[no_mangle]
pub static mut libafl_cmplog_map: CmpLogMap = CmpLogMap {
    headers: [CmpLogHeader {
        hits: 0,
        shape: 0,
        kind: 0,
    }; CMPLOG_MAP_W],
    vals: CmpLogVals {
        operands: [[CmpLogInstruction(0, 0); CMPLOG_MAP_H]; CMPLOG_MAP_W],
    },
};

and it is not possible to allocate this on heap

Version

rustc 1.65.0-nightly (1d37ed661 2022-09-09)
binary: rustc
commit-hash: 1d37ed661a6922e7a167609b8cd7eb31e972b19b
commit-date: 2022-09-09
host: aarch64-apple-darwin
release: 1.65.0-nightly
LLVM version: 15.0.0

Additional Labels

No response