riscv{32,64}-unknown-linux-musl runtime error

[calvin2021y]

import core.stdc.stdio;
extern(C) int main(int argc, char** argv){
    printf("argc=%d\n", argc);
	return 0;   
}

ldc2 -betterC -mtriple=riscv32-unknown-linux-musl test.d

/ldc/bin/../import/core/stdc/stdio.d(1464): Error: `pragma(printf)` function `vfprintf` must have signature `int vfprintf([parameters...], const(char)*, va_list)`
/ldc/bin/../import/core/stdc/stdio.d(1467): Error: `pragma(scanf)` function `vfscanf` must have signature `int vfscanf([parameters...], const(char)*, va_list)`
/ldc/bin/../import/core/stdc/stdio.d(1470): Error: `pragma(printf)` function `vsprintf` must have signature `int vsprintf([parameters...], const(char)*, va_list)`
/ldc/bin/../import/core/stdc/stdio.d(1473): Error: `pragma(scanf)` function `vsscanf` must have signature `int vsscanf([parameters...], const(char)*, va_list)`
/ldc/bin/../import/core/stdc/stdio.d(1476): Error: `pragma(printf)` function `vprintf` must have signature `int vprintf([parameters...], const(char)*, va_list)`
/ldc/bin/../import/core/stdc/stdio.d(1479): Error: `pragma(scanf)` function `vscanf` must have signature `int vscanf([parameters...], const(char)*, va_list)`
/ldc/bin/../import/core/stdc/stdio.d(1979): Error: `pragma(printf)` function `vsnprintf` must have signature `int vsnprintf([parameters...], const(char)*, va_list)`

ldc2 -betterC -mtriple=riscv64-unknown-linux-musl -c core/sys/posix/signal.d

/ldc/import/core/sys/posix/signal.d(2767): Error: static assert:  "unimplemented"
        static assert(0, "unimplemented");

[calvin2021y]

https://github.com/ldc-developers/ldc/issues/4920