compiling with clang sanitizer signals undefined behavior in rand module

[ttytm]

Describe the bug

// file.v
import rand as _

❯ v -cc clang -cflags -fsanitize=undefined run file.v
runtime error: call to function rand__wyrand__WyRandRNG_free through pointer to incorrect function type 'void (*)(void *)'
# ...
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior in... 

Reproduction Steps

above

Expected Behavior

no error

Current Behavior

runtime error about undefined behavior.

Possible Solution

No response

Additional Information/Context

Spreads to other vlib modules that import the rand module.

V version

v0.4.5

Environment details (OS name and version, etc.)

linux amd64

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[felipensp]

What clang version are you using?

[ttytm]

What clang version are you using?

Good question. 17.

I tried to do a quick repro with 14 and 15, but didn't run into the error.

[medvednikov]

Good, they keep improving the sanitizer. Perhaps we can switch to a newer version of wyrand?

[ttytm]

Good, they keep improving the sanitizer. Perhaps we can switch to a newer version of wyrand?

Yes, might be the way.

Regarding the update of the wyrand implementation, I checked out the rand module's code related to the error before reporting the issue. I was wondering about the approach of using a global for the seed and providing a public API to update the global, e.g. whether it's really is thread-safe.

v/vlib/rand/rand.v

Line 490 in 27833e0

__global default_rng &PRNG

With other wyrand implementations I've found, a seed is created on demand without using globals. Of course, without having looked deeply or used the module extensively, I may be missing the bigger picture and the advantages of the current implementation.