blosc/CMakeLists.txt: Update Lz4 handling

blosc/CMakeLists.txt

@@ -88,7 +88,7 @@ endif(WIN32)
 
 if(NOT DEACTIVATE_LZ4)
     if(LZ4_FOUND)
-        set(LIBS ${LIBS} ${LZ4_LIBRARY})
+       set(LIBS ${LZ4_LIBRARIES}) 
     else(LZ4_FOUND)
         file(GLOB LZ4_FILES ${LZ4_LOCAL_DIR}/*.c)
         set(SOURCES ${SOURCES} ${LZ4_FILES})

cmake/FindLZ4.cmake

@@ -1,12 +1,91 @@
+[==[
+Find LZ4
+Seaches system for both static and shared Lz4 binaries and headers
+If successful, sets LZ4 targets LZ4::lz4_shared and LZ4::lz4_static
+as relevant if one or both are found, and LZ4_INCLUDE_DIR.
+LZ4_LIBRARIES is also set to a generator expression containing
+one or both of the LZ4 library targets that will selectively
+use the correct type based on the library you're building.
+]==]
+# Find the lz4 include dirs
 find_path(LZ4_INCLUDE_DIR lz4.h)
 
+# Find static lz4
 # On Windows, the lz4 library is called liblz4.lib, which is not
 # found by using the lz4 name.
-find_library(LZ4_LIBRARY NAMES lz4 liblz4)
+# On native Windows lz4_static, on Darwin liblz4.a, on Linux liblz4.a
+# cache default find library suffixes so subsequent find calls behave normally
+set(ORIG_CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
+set(CMAKE_FIND_LIBRARY_SUFFIXES .lib .a)
+find_library(LZ4_STATIC_LIBRARY NAMES lz4 lz4_static liblz4)
 
-if (LZ4_INCLUDE_DIR AND LZ4_LIBRARY)
-    set(LZ4_FOUND TRUE)
-    message(STATUS "Found LZ4 library: ${LZ4_LIBRARY}")
-else ()
-    message(STATUS "No LZ4 library found.  Using internal sources.")
+# Find shared lz4
+# On Windows lz4.lib, On Darwin lz4.dylib, On Linux, lz4.so
+set(CMAKE_FIND_LIBRARY_SUFFIXES .lib .so .dylib)
+find_library(LZ4_SHARED_LIBRARY NAMES lz4 liblz4)
+if(WIN32)
+    set(CMAKE_FIND_LIBRARY_SUFFIXES .dll)
+    find_library(LZ4_DLL NAMES lz4)
+endif()
+# restore original find library behavior
+set(CMAKE_FIND_LIBRARY_SUFFIXES ${ORIG_CMAKE_FIND_LIBRARY_SUFFIXES})
+
+set(LZ4_FOUND_LIBRARIES)
+if (LZ4_STATIC_LIBRARY OR LZ4_SHARED_LIBRARY)
+    if(LZ4_STATIC_LIBRARY)
+        set(LZ4_FOUND_LIBRARIES ${LZ4_FOUND_LIBRARIES} ${LZ4_STATIC_LIBRARY})
+    endif()
+    if(LZ4_SHARED_LIBRARY)
+        set(LZ4_FOUND_LIBRARIES ${LZ4_FOUND_LIBRARIES} ${LZ4_SHARED_LIBRARY})
+    endif()
+    message(STATUS "Found LZ4 library: ${LZ4_FOUND_LIBRARIES}")
 endif ()
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(
+    LZ4
+    REQUIRED_VARS LZ4_FOUND_LIBRARIES LZ4_INCLUDE_DIR
+    REASON_FAILURE_MESSAGE "No LZ4 library found.  Using internal sources."
+)
+
+# Check if LZ4 was detected from a conig
+# module first
+if(NOT TARGET LZ4::lz4_shared)
+    add_library(LZ4::lz4_shared SHARED IMPORTED)
+    set_target_properties(LZ4::lz4_shared
+        INTERFACE_INCLUDE_DIRECTORIES ${LZ4_INCLUDE_DIR}
+    )
+    if(WIN32)
+        set_target_properties(LZ4::lz4_shared
+            IMPORTED_IMPLIB ${LZ4_SHARED_LIBRARY}
+            IMPORTED_LOCATION ${LZ4_DLL}
+        )
+    else()
+        set_target_properties(LZ4::lz4_shared
+            IMPORTED_LOCATION ${LZ4_SHARED_LIBRARY}
+        )
+    endif()
+endif()
+if(NOT TARGET LZ4::lz4_static)
+    add_library(LZ4::lz4_static STATIC IMPORTED)
+    set_target_properties(LZ4::lz4_static
+        INTERFACE_INCLUDE_DIRECTORIES ${LZ4_INCLUDE_DIR}
+        IMPORTED_LINK_INTERFACE_LANGUAGES_RELEASE "C"
+        IMPORTED_LOCATION ${LZ4_STATIC_LIBRARY}
+    )
+endif()
+
+# Set a genex to match the appropriate library type respective to the
+# type of the LZ4 library
+set(LZ4_LIBRARIES)
+if(TARGET LZ4::lz4_shared)
+    set(LZ4_LIBRARIES
+        ${LZ4_LIBRARIES}
+        $<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,SHARED_LIBRARY>:LZ4::lz4_shared>
+    )
+endif()
+if(TARGET LZ4::lz4_static)
+    set(LZ4_LIBRARIES
+        ${LZ4_LIBRARIES}
+        $<$<NOT:$<STREQUAL:$<TARGET_PROPERTY:TYPE>,SHARED_LIBRARY>>:LZ4::lz4_static>
+    )
+endif()