On Mon, Jan 02, 2017 at 07:15:31PM +0100, Andrea Bolognani wrote:
Clang 3.9 chokes when calling isnan() on a double variable:
util/virxml.c:153:21: error: implicit conversion increases
floating-point precision: 'double' to
'long double' [-Werror,-Wdouble-promotion]
(isnan(obj->floatval))) {
~~~~~~~~~~~^~~~~~~~~
/usr/include/math.h:360:46: note: expanded from macro 'isnan'
# define isnan(x) __MATH_TG ((x), __isnan, (x))
~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/math.h:295:16: note: expanded from macro '__MATH_TG'
: FUNC ## l ARGS)
~~~~~~~~~ ^~~~
Note how the wrong version of isnan() is being called: isnanl()
is for 'long double's, but obj->floatval is a double and a
suitable version should be called instead.
I don't know where do you see that ^^. Good eyes, I guess =)
Cast the value to 'long double' to make the compiler happy. --- Clang seems to be tripping on the specific way the isnan() macro is defined in recent glibc versions; more specifically, if I replace the current definition in <math.h> with the one that predates the introduction of the __MATH_TG() macro, I can get the current code to compile. I was not able to find anything wrong with the __MATH_TG() macro though.
This sounds like a glibc <=> clang problem that we shoudn't introduce more complexity for. Also *I* don't see this error, for a change =) Martin
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