finding FFTW in the env build with apt

Author: mrodrig6

toolchain/cmake/regular/FindFFTW.cmake

@@ -1,39 +1,54 @@
-# Attempt to find FFTW
-# URL:  https://www.fftw.org/
-# DOCS: https://cmake.org/cmake/help/latest/command/find_library.html
-#       https://cmake.org/cmake/help/latest/module/FindPackageHandleStandardArgs.html
+# FindFFTW.cmake — Enhanced to support apt installs, env hints, and pkg-config
 
-include(FindPackageHandleStandardArgs)
+# Try pkg-config first (if available)
+find_package(PkgConfig QUIET)
+if(PkgConfig_FOUND)
+  pkg_check_modules(PC_FFTW QUIET fftw3)
+endif()
 
+# Build include + lib search paths
+set(FFTW_HINTED_INCLUDE
+  $ENV{FFTW_INCLUDE_DIR}
+  ${PC_FFTW_INCLUDE_DIRS}
+  /usr/include
+  /usr/local/include
+)
+
+set(FFTW_HINTED_LIBRARY
+  $ENV{FFTW_LIBRARY}
+  ${PC_FFTW_LIBRARY_DIRS}
+  /usr/lib
+  /usr/lib64
+  /usr/local/lib
+  /usr/lib/x86_64-linux-gnu
+)
 
+# Locate fftw3.h and libfftw3.so
 find_path(FFTW_INCLUDE_DIR
-    NAMES         fftw3.h
-    PATH_SUFFIXES fftw fftw3
+  NAMES fftw3.h
+  HINTS ${FFTW_HINTED_INCLUDE}
 )
 
 find_library(FFTW_LIBRARY
-    NAMES         fftw3
-    PATH_SUFFIXES fftw fftw3
-    NAMES_PER_DIR
+  NAMES fftw3
+  HINTS ${FFTW_HINTED_LIBRARY}
 )
 
-
-FIND_PACKAGE_HANDLE_STANDARD_ARGS(
-    FFTW
-    REQUIRED_VARS
-        FFTW_LIBRARY
-        FFTW_INCLUDE_DIR
+# Required FFTW_FOUND logic
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(FFTW
+  REQUIRED_VARS FFTW_LIBRARY FFTW_INCLUDE_DIR
+  VERSION_VAR PC_FFTW_VERSION
 )
 
+mark_as_advanced(FFTW_INCLUDE_DIR FFTW_LIBRARY)
 
-if (FFTW_FOUND AND NOT TARGET FFTW::FFTW)
-    set(FFTW_LIBRARIES    "${FFTW_LIBRARY}")
-    set(FFTW_INCLUDE_DIRS "${FFTW_INCLUDE_DIR}")
-
-    add_library(FFTW::FFTW UNKNOWN IMPORTED)
-
-    set_target_properties(FFTW::FFTW PROPERTIES
-        IMPORTED_LOCATION             "${FFTW_LIBRARIES}"
-        INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
-    )
+# Define an imported target (optional but modern)
+if(FFTW_FOUND AND NOT TARGET FFTW::FFTW)
+  add_library(FFTW::FFTW UNKNOWN IMPORTED)
+  set_target_properties(FFTW::FFTW PROPERTIES
+    IMPORTED_LOCATION "${FFTW_LIBRARY}"
+    INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIR}"
+  )
 endif()
+

toolchain/cmake/regular/FindFFTW_legacy.cmake

@@ -0,0 +1,39 @@
+# Attempt to find FFTW
+# URL:  https://www.fftw.org/
+# DOCS: https://cmake.org/cmake/help/latest/command/find_library.html
+#       https://cmake.org/cmake/help/latest/module/FindPackageHandleStandardArgs.html
+
+include(FindPackageHandleStandardArgs)
+
+
+find_path(FFTW_INCLUDE_DIR
+    NAMES         fftw3.h
+    PATH_SUFFIXES fftw fftw3
+)
+
+find_library(FFTW_LIBRARY
+    NAMES         fftw3
+    PATH_SUFFIXES fftw fftw3
+    NAMES_PER_DIR
+)
+
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(
+    FFTW
+    REQUIRED_VARS
+        FFTW_LIBRARY
+        FFTW_INCLUDE_DIR
+)
+
+
+if (FFTW_FOUND AND NOT TARGET FFTW::FFTW)
+    set(FFTW_LIBRARIES    "${FFTW_LIBRARY}")
+    set(FFTW_INCLUDE_DIRS "${FFTW_INCLUDE_DIR}")
+
+    add_library(FFTW::FFTW UNKNOWN IMPORTED)
+
+    set_target_properties(FFTW::FFTW PROPERTIES
+        IMPORTED_LOCATION             "${FFTW_LIBRARIES}"
+        INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+    )
+endif()