[swift-users] Generic math macros on Linux

Timothy Chagnon tachagnon at gmail.com
Thu Jan 28 01:23:00 CST 2016

Hi folks,

I ran into this issue (or at least surprise) trying to compile some code
that uses math.h functions on both OSX and Linux.  Here's an example:

#if os(Linux)
  import Glibc
  import Darwin

let x = Float(1.2345)
let y = sin(x)

Compiles and runs fine on OSX, but fails with the following error on Linux:
*MathTest.swift:8:13: error: cannot convert value of type 'Float' to
expected argument type 'Double'*

I think I tracked this down to the fact that Darwin includes the
additional tgmath
style macros
that provide the overloaded sin(x: Float) -> Float swift function. Glibc
only includes plain math.h functions:
double sin(double x);
float sinf(float x);

I can, of course, just use the explicit *f math.h functions on both
platforms.  But I'm curious if this is a bug I should file or if this is
intentional to not have overloaded math functions in Swift.  I couldn't
find much mention of it in the bug tracker.

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