isnan() function is evidently not present on <math.h> on Windows before Visual Studio 2013. We define it on win32_port.h using _isnan(). However _isnan() is also not present. It is on <float.h>. The patch is attached to include this from win32_port.h.
Thanks to Thomas Munro for point this out to me [1]. It is hard to notice this issue without testing the changes on Windows. [1] https://www.postgresql.org/message-id/CAEepm%3D3dE0w%3D_dOcELpPum6suze2NZwc%3DAV4T_xYrDUoHbZJvA%40mail.gmail.com
win32_port_float_h_v00.patch
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