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Remove unnecessary const and volatile qualifiers from __fp_type_select()

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Since https://github.com/llvm/llvm-project/commit/ca75ac5f04f2, clang 15
has a new warning about _Generic selection expressions, such as used in
math.h:

    lib/libc/gdtoa/_ldtoa.c:82:10: error: due to lvalue conversion of the controlling expression, association of type 'volatile float' will never be selected because it is qualified [-Werror,-Wunreachable-code-generic-assoc]
            switch (fpclassify(u.e)) {
                    ^
    lib/msun/src/math.h:109:2: note: expanded from macro 'fpclassify'
            __fp_type_select(x, __fpclassifyf, __fpclassifyd, __fpclassifyl)
            ^
    lib/msun/src/math.h:85:14: note: expanded from macro '__fp_type_select'
        volatile float: f(x),                                               \
                 ^

This is because the controlling expression always undergoes lvalue
conversion first, dropping any cv-qualifiers. The 'const', 'volatile',
and 'volatile const' associations will therefore never be used.

MFC after:	1 week
Reviewed by:	theraven
Differential Revision: https://reviews.freebsd.org/D35815
This commit is contained in:
Dimitry Andric 2022-07-14 13:20:52 +02:00
parent 01c58e7e4f
commit e50027e38d
1 changed files with 1 additions and 10 deletions
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11
lib/msun/src/math.h
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@ -81,16 +81,7 @@ extern const union __nan_un {
#define __fp_type_select(x, f, d, ld) __extension__ _Generic((x), \
float: f(x), \
double: d(x), \
long double: ld(x), \
volatile float: f(x), \
volatile double: d(x), \
volatile long double: ld(x), \
volatile const float: f(x), \
volatile const double: d(x), \
volatile const long double: ld(x), \
const float: f(x), \
const double: d(x), \
const long double: ld(x))
long double: ld(x))
#elif __GNUC_PREREQ__(3, 1) && !defined(__cplusplus)
#define __fp_type_select(x, f, d, ld) __builtin_choose_expr( \
__builtin_types_compatible_p(__typeof(x), long double), ld(x), \