omit unnecessary casts in static arrays

[spernsteiner]

c2rust-transpile currently inserts excessive casts when translating large static arrays. For example:

static const uint8_t iv_256[32] = {
    0x6a, 0x09, 0xe6, 0x67, 0xbb, 0x67, 0xae, 0x85,
    0x3c, 0x6e, 0xf3, 0x72, 0xa5, 0x4f, 0xf5, 0x3a,
    0x51, 0x0e, 0x52, 0x7f, 0x9b, 0x05, 0x68, 0x8c,
    0x1f, 0x83, 0xd9, 0xab, 0x5b, 0xe0, 0xcd, 0x19
};

static mut IV_256: [crate::stdlib::Uint8T_0; 32] = [
    0x6a as ::core::ffi::c_int as crate::stdlib::Uint8T_0,
    0x9 as ::core::ffi::c_int as crate::stdlib::Uint8T_0,
    0xe6 as ::core::ffi::c_int as crate::stdlib::Uint8T_0,
    0x67 as ::core::ffi::c_int as crate::stdlib::Uint8T_0,
    // 28 more lines ...
];

These casts are unnecessary because the type of each literal is constrained by the declared type of the static. Removing them would make the code much less verbose and more readable. This could likely be done as a postprocessing pass in c2rust-refactor.

[ahomescu]

remove_redundant_casts already does some of this (even better if followed up by remove_literal_suffixes). I'm not sure we enabled it by default, did you try running it manually?

[spernsteiner]

I haven't tried it. I added a note to GaloisInc/Tractor-Crisp#84 for whoever ends up taking that on.