Hi Sam, > The configure test in gl_FUNC_FREXP_WORKS within m4/frexp.m4 triggers > a Clang warning/error when Clang is passed > -Werror=incompatible-pointer-types.
Gnulib does not support CC or CPPFLAGS or CFLAGS values with -Werror at configure time. Neither with gcc nor with clang. The reason is that [1] "Many GCC warning options usually don’t point to mistakes in the code; these warnings enforce a certain programming style. It is a project management decision whether you want your code to follow any of these styles. Note that some of these programming styles are conflicting. You cannot have them all; you have to choose among them." For example, there is a warning option that attempts to enforce explicit casts (no implicit conversions), and there is a warning option that attempts to enforce no explicit casts. When you use such a warning option together with -Werror, you are attempting to enforce a certain programming style on the configure tests. Obviously the configure test snippets cannot obey different, conflicting programming styles. > /tmp/foo.c: In function ‘main’: > /tmp/foo.c:59:21: warning: passing argument 2 of ‘memcmp’ discards ‘volatile’ > qualifier from pointer target type [-Wdiscarded-qualifiers] > 59 | if (memcmp (&y, &x, sizeof x)) > | ^~ There is nothing wrong with this code (m4/frexp.m4:159, m4/frexpf.m4:83). We don't want to add a cast here, because — as Paul argues — casts can make code more difficult to maintain in the long run. Bruno [1] https://www.gnu.org/software/gnulib/manual/html_node/manywarnings.html
