From 16377d39eafe9b272d718d7936d26fd94b20402e Mon Sep 17 00:00:00 2001
From: Chris Degawa <ccom@randomderp.com>
Date: Tue, 9 Apr 2019 13:18:30 -0500
Subject: [PATCH] mingw-w64 cmake: Don't find libm

mingw-w64 will provide libm symbols by default without -lm and mingw-64's
libm is just a stub.

This is just to make sure that on systems with msys2 and also cygwin, cmake
doesn't find a libm that actually contains math functions.
---
 CMakeLists.txt | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d0285be0..fbc74bbe 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -203,7 +203,9 @@ else()
 endif()
 
 # Find libm, if available
-find_library(M_LIBRARY m)
+if(NOT MINGW)
+  find_library(M_LIBRARY m)
+endif()
 
 check_include_file(assert.h    HAVE_ASSERT_H)
 check_include_file(dlfcn.h     HAVE_DLFCN_H)
@@ -671,7 +673,7 @@ endif()
 
 # Libraries required by libtiff
 set(TIFF_LIBRARY_DEPS)
-if(M_LIBRARY)
+if(NOT MINGW AND M_LIBRARY)
   list(APPEND TIFF_LIBRARY_DEPS ${M_LIBRARY})
 endif()
 if(ZLIB_LIBRARIES)