Add a "fork" of musl as //fusl.

fusl/include/tgmath.h

+#ifndef _TGMATH_H
+#define _TGMATH_H
+
+/*
+the return types are only correct with gcc (__GNUC__)
+otherwise they are long double or long double complex
+
+the long double version of a function is never chosen when
+sizeof(double) == sizeof(long double)
+(but the return type is set correctly with gcc)
+*/
+
+#include <math.h>
+#include <complex.h>
+
+#define __IS_FP(x) (sizeof((x)+1ULL) == sizeof((x)+1.0f))
+#define __IS_CX(x) (__IS_FP(x) && sizeof(x) == sizeof((x)+I))
+#define __IS_REAL(x) (__IS_FP(x) && 2*sizeof(x) == sizeof((x)+I))
+
+#define __FLT(x) (__IS_REAL(x) && sizeof(x) == sizeof(float))
+#define __LDBL(x) (__IS_REAL(x) && sizeof(x) == sizeof(long double) && sizeof(long double) != sizeof(double))
+
+#define __FLTCX(x) (__IS_CX(x) && sizeof(x) == sizeof(float complex))
+#define __DBLCX(x) (__IS_CX(x) && sizeof(x) == sizeof(double complex))
+#define __LDBLCX(x) (__IS_CX(x) && sizeof(x) == sizeof(long double complex) && sizeof(long double) != sizeof(double))
+
+/* return type */
+
+#ifdef __GNUC__
+/*
+the result must be casted to the right type
+(otherwise the result type is determined by the conversion
+rules applied to all the function return types so it is long
+double or long double complex except for integral functions)
+
+this cannot be done in c99, so the typeof gcc extension is
+used and that the type of ?: depends on wether an operand is
+a null pointer constant or not
+(in c11 _Generic can be used)
+
+the c arguments below must be integer constant expressions
+so they can be in null pointer constants
+(__IS_FP above was carefully chosen this way)
+*/
+/* if c then t else void */
+#define __type1(c,t) __typeof__(*(0?(t*)0:(void*)!(c)))
+/* if c then t1 else t2 */
+#define __type2(c,t1,t2) __typeof__(*(0?(__type1(c,t1)*)0:(__type1(!(c),t2)*)0))
+/* cast to double when x is integral, otherwise use typeof(x) */
+#define __RETCAST(x) ( \
+        __type2(__IS_FP(x), __typeof__(x), double))
+/* 2 args case, should work for complex types (cpow) */
+#define __RETCAST_2(x, y) ( \
+        __type2(__IS_FP(x) && __IS_FP(y), \
+                __typeof__((x)+(y)), \
+                __typeof__((x)+(y)+1.0)))
+/* 3 args case (fma only) */
+#define __RETCAST_3(x, y, z) ( \
+        __type2(__IS_FP(x) && __IS_FP(y) && __IS_FP(z), \
+                __typeof__((x)+(y)+(z)), \
+                __typeof__((x)+(y)+(z)+1.0)))
+/* drop complex from the type of x */
+/* TODO: wrong when sizeof(long double)==sizeof(double) */
+#define __RETCAST_REAL(x) (  \
+        __type2(__IS_FP(x) && sizeof((x)+I) == sizeof(float complex), float, \
+        __type2(sizeof((x)+1.0+I) == sizeof(double complex), double, \
+                long double)))
+/* add complex to the type of x */
+#define __RETCAST_CX(x) (__typeof__(__RETCAST(x)0+I))
+#else
+#define __RETCAST(x)
+#define __RETCAST_2(x, y)
+#define __RETCAST_3(x, y, z)
+#define __RETCAST_REAL(x)
+#define __RETCAST_CX(x)
+#endif
+
+/* function selection */
+
+#define __tg_real_nocast(fun, x) ( \
+        __FLT(x) ? fun ## f (x) : \
+        __LDBL(x) ? fun ## l (x) : \
+        fun(x) )
+
+#define __tg_real(fun, x) (__RETCAST(x)__tg_real_nocast(fun, x))
+
+#define __tg_real_2_1(fun, x, y) (__RETCAST(x)( \
+        __FLT(x) ? fun ## f (x, y) : \
+        __LDBL(x) ? fun ## l (x, y) : \
+        fun(x, y) ))
+
+#define __tg_real_2(fun, x, y) (__RETCAST_2(x, y)( \
+        __FLT(x) && __FLT(y) ? fun ## f (x, y) : \
+        __LDBL((x)+(y)) ? fun ## l (x, y) : \
+        fun(x, y) ))
+
+#define __tg_complex(fun, x) (__RETCAST_CX(x)( \
+        __FLTCX((x)+I) && __IS_FP(x) ? fun ## f (x) : \
+        __LDBLCX((x)+I) ? fun ## l (x) : \
+        fun(x) ))
+
+#define __tg_complex_retreal(fun, x) (__RETCAST_REAL(x)( \
+        __FLTCX((x)+I) && __IS_FP(x) ? fun ## f (x) : \
+        __LDBLCX((x)+I) ? fun ## l (x) : \
+        fun(x) ))
+
+#define __tg_real_complex(fun, x) (__RETCAST(x)( \
+        __FLTCX(x) ? c ## fun ## f (x) : \
+        __DBLCX(x) ? c ## fun (x) : \
+        __LDBLCX(x) ? c ## fun ## l (x) : \
+        __FLT(x) ? fun ## f (x) : \
+        __LDBL(x) ? fun ## l (x) : \
+        fun(x) ))
+
+/* special cases */
+
+#define __tg_real_remquo(x, y, z) (__RETCAST_2(x, y)( \
+        __FLT(x) && __FLT(y) ? remquof(x, y, z) : \
+        __LDBL((x)+(y)) ? remquol(x, y, z) : \
+        remquo(x, y, z) ))
+
+#define __tg_real_fma(x, y, z) (__RETCAST_3(x, y, z)( \
+        __FLT(x) && __FLT(y) && __FLT(z) ? fmaf(x, y, z) : \
+        __LDBL((x)+(y)+(z)) ? fmal(x, y, z) : \
+        fma(x, y, z) ))
+
+#define __tg_real_complex_pow(x, y) (__RETCAST_2(x, y)( \
+        __FLTCX((x)+(y)) && __IS_FP(x) && __IS_FP(y) ? cpowf(x, y) : \
+        __FLTCX((x)+(y)) ? cpow(x, y) : \
+        __DBLCX((x)+(y)) ? cpow(x, y) : \
+        __LDBLCX((x)+(y)) ? cpowl(x, y) : \
+        __FLT(x) && __FLT(y) ? powf(x, y) : \
+        __LDBL((x)+(y)) ? powl(x, y) : \
+        pow(x, y) ))
+
+#define __tg_real_complex_fabs(x) (__RETCAST_REAL(x)( \
+        __FLTCX(x) ? cabsf(x) : \
+        __DBLCX(x) ? cabs(x) : \
+        __LDBLCX(x) ? cabsl(x) : \
+        __FLT(x) ? fabsf(x) : \
+        __LDBL(x) ? fabsl(x) : \
+        fabs(x) ))
+
+/* suppress any macros in math.h or complex.h */
+
+#undef acos
+#undef acosh
+#undef asin
+#undef asinh
+#undef atan
+#undef atan2
+#undef atanh
+#undef carg
+#undef cbrt
+#undef ceil
+#undef cimag
+#undef conj
+#undef copysign
+#undef cos
+#undef cosh
+#undef cproj
+#undef creal
+#undef erf
+#undef erfc
+#undef exp
+#undef exp2
+#undef expm1
+#undef fabs
+#undef fdim
+#undef floor
+#undef fma
+#undef fmax
+#undef fmin
+#undef fmod
+#undef frexp
+#undef hypot
+#undef ilogb
+#undef ldexp
+#undef lgamma
+#undef llrint
+#undef llround
+#undef log
+#undef log10
+#undef log1p
+#undef log2
+#undef logb
+#undef lrint
+#undef lround
+#undef nearbyint
+#undef nextafter
+#undef nexttoward
+#undef pow
+#undef remainder
+#undef remquo
+#undef rint
+#undef round
+#undef scalbln
+#undef scalbn
+#undef sin
+#undef sinh
+#undef sqrt
+#undef tan
+#undef tanh
+#undef tgamma
+#undef trunc
+
+/* tg functions */
+
+#define acos(x)         __tg_real_complex(acos, (x))
+#define acosh(x)        __tg_real_complex(acosh, (x))
+#define asin(x)         __tg_real_complex(asin, (x))
+#define asinh(x)        __tg_real_complex(asinh, (x))
+#define atan(x)         __tg_real_complex(atan, (x))
+#define atan2(x,y)      __tg_real_2(atan2, (x), (y))
+#define atanh(x)        __tg_real_complex(atanh, (x))
+#define carg(x)         __tg_complex_retreal(carg, (x))
+#define cbrt(x)         __tg_real(cbrt, (x))
+#define ceil(x)         __tg_real(ceil, (x))
+#define cimag(x)        __tg_complex_retreal(cimag, (x))
+#define conj(x)         __tg_complex(conj, (x))
+#define copysign(x,y)   __tg_real_2(copysign, (x), (y))
+#define cos(x)          __tg_real_complex(cos, (x))
+#define cosh(x)         __tg_real_complex(cosh, (x))
+#define cproj(x)        __tg_complex(cproj, (x))
+#define creal(x)        __tg_complex_retreal(creal, (x))
+#define erf(x)          __tg_real(erf, (x))
+#define erfc(x)         __tg_real(erfc, (x))
+#define exp(x)          __tg_real_complex(exp, (x))
+#define exp2(x)         __tg_real(exp2, (x))
+#define expm1(x)        __tg_real(expm1, (x))
+#define fabs(x)         __tg_real_complex_fabs(x)
+#define fdim(x,y)       __tg_real_2(fdim, (x), (y))
+#define floor(x)        __tg_real(floor, (x))
+#define fma(x,y,z)      __tg_real_fma((x), (y), (z))
+#define fmax(x,y)       __tg_real_2(fmax, (x), (y))
+#define fmin(x,y)       __tg_real_2(fmin, (x), (y))
+#define fmod(x,y)       __tg_real_2(fmod, (x), (y))
+#define frexp(x,y)      __tg_real_2_1(frexp, (x), (y))
+#define hypot(x,y)      __tg_real_2(hypot, (x), (y))
+#define ilogb(x)        __tg_real_nocast(ilogb, (x))
+#define ldexp(x,y)      __tg_real_2_1(ldexp, (x), (y))
+#define lgamma(x)       __tg_real(lgamma, (x))
+#define llrint(x)       __tg_real_nocast(llrint, (x))
+#define llround(x)      __tg_real_nocast(llround, (x))
+#define log(x)          __tg_real_complex(log, (x))
+#define log10(x)        __tg_real(log10, (x))
+#define log1p(x)        __tg_real(log1p, (x))
+#define log2(x)         __tg_real(log2, (x))
+#define logb(x)         __tg_real(logb, (x))
+#define lrint(x)        __tg_real_nocast(lrint, (x))
+#define lround(x)       __tg_real_nocast(lround, (x))
+#define nearbyint(x)    __tg_real(nearbyint, (x))
+#define nextafter(x,y)  __tg_real_2(nextafter, (x), (y))
+#define nexttoward(x,y) __tg_real_2(nexttoward, (x), (y))
+#define pow(x,y)        __tg_real_complex_pow((x), (y))
+#define remainder(x,y)  __tg_real_2(remainder, (x), (y))
+#define remquo(x,y,z)   __tg_real_remquo((x), (y), (z))
+#define rint(x)         __tg_real(rint, (x))
+#define round(x)        __tg_real(round, (x))
+#define scalbln(x,y)    __tg_real_2_1(scalbln, (x), (y))
+#define scalbn(x,y)     __tg_real_2_1(scalbn, (x), (y))
+#define sin(x)          __tg_real_complex(sin, (x))
+#define sinh(x)         __tg_real_complex(sinh, (x))
+#define sqrt(x)         __tg_real_complex(sqrt, (x))
+#define tan(x)          __tg_real_complex(tan, (x))
+#define tanh(x)         __tg_real_complex(tanh, (x))
+#define tgamma(x)       __tg_real(tgamma, (x))
+#define trunc(x)        __tg_real(trunc, (x))
+
+#endif