assert: output more detailed messages

[chqrlie]

• output values of non-literal assert expression comparison operands
• output values of non-literal static_assert operands

[bvdberg]

old:
static_assert(3, 4); // @error{static_assert failed, expected 3, got 4}
new:
static_assert(3, 4); // @error{static_assert failed: 3 == 4}

I think the old message is clearer right? with 3==4 you dont know which was correct?

This patch also grows the c2c binary by 12 KB...

[chqrlie]

old: static_assert(3, 4); // @error{static_assert failed, expected 3, got 4}

new: static_assert(3, 4); // @error{static_assert failed: 3 == 4}

I think the old message is clearer right? with 3==4 you dont know which was correct?

I made the error message consistent with assert(3 == 4). If both arguments are literals, there is no correct argument value, and the assertion that failed is effectively 3 == 4. If you write static_assert(sizeof(S), 4), then the message is static_assert failed: sizeof(S) == 4, got 3, maybe it should be static_assert failed: sizeof(S) == 4, sizeof(S): 3.

With this PR, assert(sizeof(S) == 4); produces a runtime error Assertion failed: sizeof(S) == 4, sizeof(S): 3`

My goal is to make static_assert more consistent with the C and C++ equivalent where the assertion is an expression, not 2 separate arguments and consistent with the assert statement, producing more explicit error messages.

This patch also grows the c2c binary by 12 KB...

The code generated for the 345 assert statements is slightly larger with the explicit sub-expression strings and computed values. I can try and reduce the number of strings generated.