Modern CMake syntax in giflib

Modernized the CMake syntax to align more with the modern CMake.

giflib/CMakeLists.txt

@@ -1,18 +1,17 @@
-PROJECT(giflib C)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.5 FATAL_ERROR)
 
-SET(TARGET_LIB giflib)
+FILE(READ ${GIFLIB_SOURCE_DIR}/lib/gif_lib.h _gif_lib_h_contents)
+STRING(REGEX REPLACE ".*#define[ \t]+GIFLIB_MAJOR[ \t]+([0-9]+).*" "\\1" GIFLIB_MAJOR_VERSION ${_gif_lib_h_contents})
+STRING(REGEX REPLACE ".*#define[ \t]+GIFLIB_MINOR[ \t]+([0-9]+).*" "\\1" GIFLIB_MINOR_VERSION ${_gif_lib_h_contents})
+STRING(REGEX REPLACE ".*#define[ \t]+GIFLIB_RELEASE[ \t]+([0-9]+).*" "\\1" GIFLIB_RELEASE_VERSION ${_gif_lib_h_contents})
 
-SET(GIFLIB_VERSION_FILE "${GIFLIB_SOURCE_DIR}/lib/gif_lib.h")
-
-IF(EXISTS "${GIFLIB_VERSION_FILE}") 
-  FILE(STRINGS "${GIFLIB_VERSION_FILE}" GIFLIB_VERSION_FILE_CONTENTS REGEX "#define GIFLIB_[A-Z]+[ \t]+[0-9]+")
+PROJECT(giflib VERSION "${GIFLIB_MAJOR_VERSION}.${GIFLIB_MINOR_VERSION}.${GIFLIB_RELEASE_VERSION}" LANGUAGES C)
+
+
+# Use GNUInstallDirs to install libraries into correct
+# locations on all platforms.
+INCLUDE(GNUInstallDirs)
 
-  STRING(REGEX REPLACE ".*#define GIFLIB_MAJOR[ \t]+([0-9]+).*" "\\1" GIFLIB_VERSION_MAJOR ${GIFLIB_VERSION_FILE_CONTENTS})
-  STRING(REGEX REPLACE ".*#define GIFLIB_MINOR[ \t]+([0-9]+).*" "\\1" GIFLIB_VERSION_MINOR ${GIFLIB_VERSION_FILE_CONTENTS})
-  STRING(REGEX REPLACE ".*#define GIFLIB_RELEASE[ \t]+([0-9]+).*" "\\1" GIFLIB_VERSION_RELEASE ${GIFLIB_VERSION_FILE_CONTENTS})
-
-  SET(GIFLIB_VERSION "${GIFLIB_VERSION_MAJOR}.${GIFLIB_VERSION_MINOR}.${GIFLIB_VERSION_RELEASE}")
-ENDIF()
 
 SET(GIFLIB_PUBLIC_HEADERS
   ${GIFLIB_SOURCE_DIR}/lib/gif_lib.h
@@ -31,16 +30,8 @@ SET(GIFLIB_SRCS
   ${GIFLIB_SOURCE_DIR}/lib/gif_hash.c
   ${GIFLIB_SOURCE_DIR}/lib/gifalloc.c
   ${GIFLIB_SOURCE_DIR}/lib/quantize.c
-)
-
-# Add openbsd-reallocarray from 5.1.2 and up
-IF(NOT GIFLIB_VERSION VERSION_LESS 5.1.2)
-  SET(GIFLIB_SRCS
-    ${GIFLIB_SRCS}
-    ${GIFLIB_SOURCE_DIR}/lib/openbsd-reallocarray.c
+  ${GIFLIB_SOURCE_DIR}/lib/openbsd-reallocarray.c
   )
-ENDIF()
-
 
 IF(MSVC)
   # Create file to avoid include file name collision on other platforms
@@ -67,36 +58,61 @@ IF(MSVC)
   )
 ENDIF(MSVC)
 
-
-# Dependent include files
-INCLUDE_DIRECTORIES(${GIFLIB_SOURCE_DIR} ${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_BINARY_DIR})
-
 IF(MSVC)
-  SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4018 /wd4028 /wd4244 /wd4996")
-  ADD_DEFINITIONS(-D_CRT_SECURE_NO_WARNINGS -D_LIB -DWIN32)
+  LIST(APPEND PRIVATE_DEFINITIONS -D_CRT_SECURE_NO_WARNINGS) # Disable warnings for unsecure CRT functions
+  LIST(APPEND PRIVATE_DEFINITIONS -D_LIB) # 
+  LIST(APPEND PRIVATE_DEFINITIONS -DWIN32) # 
+
+  # Supress warnings
+  LIST(APPEND PRIVATE_OPTIONS /wd4018) # expression' : signed/unsigned mismatch
+  LIST(APPEND PRIVATE_OPTIONS /wd4028) # formal parameter 'number' different from declaration
+  LIST(APPEND PRIVATE_OPTIONS /wd4244) # conversion' conversion from 'type1' to 'type2', possible loss of data
+  LIST(APPEND PRIVATE_OPTIONS /wd4996) # The compiler encountered a deprecated declaration.
+
+
   SET(CMAKE_DEBUG_POSTFIX "d")
 ENDIF(MSVC)
 
+
 IF(MINGW)
-  ADD_DEFINITIONS(-D_CRT_SECURE_NO_WARNINGS -D_LIB)
+  LIST(APPEND PRIVATE_DEFINITIONS -D_CRT_SECURE_NO_WARNINGS) # Disable warnings for unsecure CRT functions
+  LIST(APPEND PRIVATE_DEFINITIONS -D_LIB) # 
 ENDIF(MINGW)
 
-ADD_LIBRARY(${TARGET_LIB} STATIC ${GIFLIB_SRCS} ${GIFLIB_PRIVATE_HEADERS} ${GIFLIB_PUBLIC_HEADERS})
+ADD_LIBRARY(giflib STATIC ${GIFLIB_SRCS} ${GIFLIB_PUBLIC_HEADERS} ${GIFLIB_PRIVATE_HEADERS})
+
+# Dependent include files
+TARGET_INCLUDE_DIRECTORIES(giflib PUBLIC 
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}> 
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+  $<INSTALL_INTERFACE:include>
+  )
+
+TARGET_COMPILE_DEFINITIONS(giflib
+  PRIVATE ${PRIVATE_DEFINITIONS}
+  )
+
+
+TARGET_COMPILE_OPTIONS(giflib 
+  PRIVATE ${PRIVATE_OPTIONS}
+  )
 
 IF(MINGW)
   SET_TARGET_PROPERTIES(${TARGET_LIB} PROPERTIES OUTPUT_NAME gif)
 ENDIF()
 
-# Runtime equals DLL-files
-# Archive equals static libraries
-# Library equals module libraries
-IF(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
-  INSTALL(TARGETS ${TARGET_LIB}
-    RUNTIME DESTINATION ${EXECUTABLE_OUTPUT_PATH}
-    LIBRARY DESTINATION ${LIBRARY_OUTPUT_PATH}
-    ARCHIVE DESTINATION ${ARCHIVE_OUTPUT_PATH})
-ENDIF()
 
-IF(NOT SKIP_INSTALL_HEADERS AND NOT SKIP_INSTALL_ALL )
-  INSTALL(FILES ${GIFLIB_PUBLIC_HEADERS} DESTINATION ${INCLUDE_OUTPUT_PATH})
-ENDIF()
+# INSTALL
+INSTALL(TARGETS giflib EXPORT giflib_export
+  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+  )
+
+INSTALL(FILES 
+  ${GIFLIB_PUBLIC_HEADERS} 
+  DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+  )
+
+