builtin, cgen: improve the assert informations (related #22666)

[yuyi98]

This PR improve the assert informations (related #22666).

type Sum = int | string

fn main() {
	assert Sum(1) == Sum(2)
}

PS D:\Test\v\tt1> v run .    
.\\tt1.v:4: FAIL: fn main.main: assert main.Sum(1) == main.Sum(2)
  left value: main.Sum(1)
  right value: main.Sum(2)
V panic: Assertion failed...
v hash: 14b1a14
C:/Users/yuyi9/AppData/Local/Temp/v_0/tt1.01JB6ZGGR5EPG0CM0FD2MRVCFX.tmp.c:7314: at _v_panic: Backtrace
C:/Users/yuyi9/AppData/Local/Temp/v_0/tt1.01JB6ZGGR5EPG0CM0FD2MRVCFX.tmp.c:13684: by main__main
C:/Users/yuyi9/AppData/Local/Temp/v_0/tt1.01JB6ZGGR5EPG0CM0FD2MRVCFX.tmp.c:13721: by wmain
00466ea8 : by ???
0046700b : by ???
7ffe207e259d : by ???

_{Huly®: V_0.6-21117}

[enghitalo]

Great!!!

[spytheman]

Excellent work.

Please add a .vv/.out pair too in vlib/v/slow_tests/inout/ (include only the system independent part before the panic in the .out file; see ./vlib/v/slow_tests/inout/panic_on_fixed_array_slice.out for example) and it will be good to merge.

The _test.vv/.run.out pair is better to be placed in vlib/v/tests/skip_unused/, see below.

[spytheman]

vlib/v/tests/skip_unused/assert_of_sumtype_values_works_test.vv with:

type Sum = int | string

fn test_ab() {
        a,b := Sum(1), Sum(2)
        assert a == b
}

fn test_sumtype_literals() {
        assert Sum(1) == Sum(2)
}

can be tested by vlib/v/tests/skip_unused/assert_of_sumtype_values_works_test.run.out:

vlib/v/tests/skip_unused/assert_of_sumtype_values_works_test.vv:5: fn test_ab
   > assert a == b
     Left value (len: 6): `Sum(1)`
    Right value (len: 6): `Sum(2)`

vlib/v/tests/skip_unused/assert_of_sumtype_values_works_test.vv:9: fn test_sumtype_literals
   > assert main.Sum(1) == main.Sum(2)
     Left value (len: 11): `main.Sum(1)`
    Right value (len: 11): `main.Sum(2)`
    

Can we remove the main. prefix, so that it is the same as the test_ab failure?

[spytheman]

I've added the test pair.
You can test locally with VTEST_ONLY=assert_of_sumtype_values_works VAUTOFIX=1 ./v vlib/v/compiler_errors_test.v