Hello Alex, On 9/5/20 5:14 PM, Alejandro Colomar wrote: > Casting `void *` to `double (*cosine)(double)` is already done > implicitly. > I had doubts about this one, but `gcc -Wall -Wextra` didn't complain > about it. > Explicitly casting can silence warnings when mistakes are made, so it's > better to remove those casts when possible. > > Signed-off-by: Alejandro Colomar <colomar.6.4.3@xxxxxxxxx> > --- > man3/dlopen.3 | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/man3/dlopen.3 b/man3/dlopen.3 > index 8e18f70c0..2de358ea3 100644 > --- a/man3/dlopen.3 > +++ b/man3/dlopen.3 > @@ -581,7 +581,7 @@ main(void) > > dlerror(); /* Clear any existing error */ > > - cosine = (double (*)(double)) dlsym(handle, "cos"); > + cosine = dlsym(handle, "cos"); > > /* According to the ISO C standard, casting between function > pointers and 'void *', as done above, produces undefined results. This cast really is needed. See the comment just below, and also try compiling the code with your patch applied: cc -pedantic -Wall prog.c d.c: In function ‘main’: d.c:21:19: warning: ISO C forbids assignment between function pointer and ‘void *’ [-Wpedantic] 21 | cosine = dlsym(handle, "cos"); | ^ Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/