`@trusted pragma(printf)` function is only safe to call if it has `...` parameter

[ntrel]

pragma(printf) allows a va_list parameter, not just ...:

import core.stdc.stdarg;

extern(C) pragma(printf) int vprintf(const char*, va_list) @trusted;

void f() @safe
{
    va_list args;
    vprintf("%d", args); // allowed, should error
}

PR incoming.

[ntrel]

Although vprintf is trusted, its signature is wrong by definition. It cannot have a safe interface.