Commit 052079c99455d01312d377d72fa1b8b5c0b22aad surfaced two issues with
the generated C code:
- renderInt128() contained a seemingly unnecessary assertion to verify
that the high 64 bits of the number were nonzero, dating back to
9bf1681990fe87a6b2e5fc644a89f1aece304579. I removed it.
- renderValue() didn't have any special handling for undefined structs,
falling back to printing "{}" which generated invalid expressions
such as "return {}" for functions returning structs, whereas
"return (S){}" is the correct form. I changed it accordingly.
At the same time I'm reenabling the relevant tests.
* Identify the ones that are passing and stop skipping them.
* Flatten out the main behavior.zig file and have each individual test
disable itself if it is not passing.
Instead use the standarized option for communicating the
zig compiler backend at comptime, which is `zig_backend`. This was
introduced in commit 1c24ef0d0b09a12a1fe98056f2fc04de78a82df3.
-add additional test cases that were found to be passing
-add basic int128 test cases which previously did not pass but weren't covered
-most test cases in cast.zig now pass
-i128/u128 or smaller int constants can now be rendered
-unsigned int constants are now always suffixed with 'u' to prevent random compile errors
-pointers with a val tag of 'zero' now just emit a 0 constant which coerces to the pointer type and fixes some warnings with ordered comparisons
-pointers with a val tag of 'one' are now casted back to the pointer type
-support pointers with a u64 val
-fix bug where rendering an array's type will emit more indirection than is needed
-render uint128_t/int128_t manually when needed
-implement ptr_add/sub AIR handlers manually so they manually cast to int types which avoids UB if the result or ptr operand is NULL
-implement airPtrElemVal/Ptr
-airAlloc for arrays will not allocate a ref as the local for the array is already a reference/pointer to the array itself
-fix airPtrToInt by casting to the int type
