[PATCH v1] man/man3/dlopen.3: EXAMPLES: Simplify use of dlsym(3)

The cast is entirely unnecessary.  Conversion from/to void* and function
pointers is implicit, and it's guaranteed by POSIX.  ISO C is irrelevant
here, because dlsym(3) requires POSIX, which provides the stronger
guarantees that we need.

And even before POSIX standardized these guarantees about void* and
function pointers, and system implementing dlsym(3) would have to
support them anyway, as otherwise dlsym(3) couldn't work at all.

Reported-by: Bruno Haible <[email protected]>
Suggested-by: Martin Uecker <[email protected]>
Cc: Walter Harms <[email protected]>
Signed-off-by: Alejandro Colomar <[email protected]>
---
 man/man3/dlopen.3 | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/man/man3/dlopen.3 b/man/man3/dlopen.3
index 482af099..d9be7502 100644
--- a/man/man3/dlopen.3
+++ b/man/man3/dlopen.3
@@ -567,23 +567,11 @@ .SS Program source
 \&
     dlerror();    /* Clear any existing error */
 \&
-    cosine = (typeof(double (double)) *) dlsym(handle, "cos");
+    cosine = dlsym(handle, "cos");
 \&
-    /* According to the ISO C standard, casting between function
-       pointers and \[aq]void *\[aq], as done above, produces undefined results.
-       POSIX.1\-2001 and POSIX.1\-2008 accepted this state of affairs and
-       proposed the following workaround:
-\&
-           *(void **) &cosine = dlsym(handle, "cos");
-\&
-       This (clumsy) cast conforms with the ISO C standard and will
-       avoid any compiler warnings.
-\&
-       The 2013 Technical Corrigendum 1 to POSIX.1\-2008 improved matters
-       by requiring that conforming implementations support casting
-       \[aq]void *\[aq] to a function pointer.  Nevertheless, some compilers
-       (e.g., gcc with the \[aq]\-pedantic\[aq] option) may complain about the
-       cast used in this program.  */
+    /* The 2013 Technical Corrigendum 1 to POSIX.1\-2008
+       required that conforming implementations support
+       converting \[aq]void *\[aq] to a function pointer.  */
 .\" http://pubs.opengroup.org/onlinepubs/009695399/functions/dlsym.html#tag_03_112_08
 .\" http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlsym.html#tag_16_96_07
 .\" http://austingroupbugs.net/view.php?id=74

Range-diff against v0:
-:  -------- > 1:  508bb497 man/man3/dlopen.3: EXAMPLES: Simplify use of dlsym(3)
-- 
2.53.0