`-nan + 0 = +nan` on riscv64

As stated in the riscv reference here: https://docs.riscv.org/reference/isa/unpriv/f-st-ext.html#21-1-3-nan-generation-and-propagation > Except when otherwise stated, if the result of a floating-point operation is NaN, it is the canonical NaN. The canonical NaN has a positive sign and all significand bits clear except the MSB, a.k.a. the quiet bit. With relevance to awk, since awk uses `double`-precision floats for numbers, canonical NaN translates to `+nan = 7ff8000000000000`. In https://github.com/onetrueawk/awk/blob/5739fd79bcfc75ba7526773d0cf634521f8aca3c/bugs-fixed/inf-nan-torture.in#L1, line 4 asserts that `-nan + 0 = -nan`, but this is NOT true on riscv64. Here's a minimal repro that shows the issue on both gcc and clang on riscv64: ```c #include <inttypes.h> #include <math.h> #include <stdio.h> #include <stdint.h> #include <string.h> #define myprint(d) do { \ double _d = (d); \ uint64_t _u; \ memcpy(&_u, &_d, sizeof(_d)); \ printf("%s = %f %" PRIx64 "\n", #d, _d, _u); \ } while (0) int main(void) { double f = -NAN; double g = 0; myprint(f); myprint(g); myprint(-NAN + 0); myprint(f + g); } ``` Thus, that testcase is not portable. Downstream, we can see the test failure on FreeBSD in CI here: https://ci.freebsd.org/job/FreeBSD-main-riscv64-test/16606/testReport/usr.bin.awk.bugs-fixed/bug_fix_test/inf_nan_torture/