From 49366d0455a78f8be7b1c16569c04d53e6e264a1 Mon Sep 17 00:00:00 2001
From: Bill Somerville <bill@classdesign.com>
Date: Sat, 22 Aug 2020 02:40:33 +0100
Subject: [PATCH] CMake 3.17 compatibility

---
 CMake/Modules/FindFFTW3.cmake | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/CMake/Modules/FindFFTW3.cmake b/CMake/Modules/FindFFTW3.cmake
index 10349cb69..3bcfd88c3 100644
--- a/CMake/Modules/FindFFTW3.cmake
+++ b/CMake/Modules/FindFFTW3.cmake
@@ -34,6 +34,12 @@
 #
 # $Id: FindFFTW3.cmake 15918 2010-06-25 11:12:42Z loose $
 
+# Compatibily with old style MinGW packages with no .dll.a files
+# needed since CMake v3.17 because of fix for #20019
+if (MINGW)
+  set (CMAKE_FIND_LIBRARY_SUFFIXES ".dll" ".dll.a" ".a" ".lib")
+endif ()
+
 # Use double precision by default.
 if (FFTW3_FIND_COMPONENTS MATCHES "^$")
   set (_components double)
@@ -75,7 +81,7 @@ set (_check_list)
 foreach (_lib ${_libraries})
   string (TOUPPER ${_lib} _LIB)
   find_library (${_LIB}_LIBRARY NAMES ${_lib} ${_lib}-3
-    HINTS ${FFTW3_ROOT_DIR} PATH_SUFFIXES lib)
+    PATH_SUFFIXES lib)
   mark_as_advanced (${_LIB}_LIBRARY)
   list (APPEND FFTW3_LIBRARIES ${${_LIB}_LIBRARY})
   list (APPEND _check_list ${_LIB}_LIBRARY)