Various cmake improvements

Use scripts/version.sh, and set version in project() using its output.
Instead of using a variable to store the definition of
TINYALSA_USES_PLUGINS, and adding it as a compile option, use a
generator expression to define it in target_compile_definitions when the
option is enabled.
Set BUILD_SHARED_LIBS to on by default.
Add options to disable examples and utils.
Instead of using SRCS and HDRS variables, set PUBLIC_HEADER property on
tinyalsa to install the headers along with the target.
Set library version, so the shared library will have version suffixes.
Check that C warning flags are supported instead of adding them
unconditionally.
Use ${CMAKE_DL_LIBS} instead of hardcoding "dl", and add it to
tinyalsa's link interface and link depends, instead of linking it in the
examples and utils.
Add the "include" directory as a PUBLIC include directory to tinyalsa,
instead of making it PRIVATE and adding it to examples and utils as
well, because anything linking the tinyalsa target will need to include
"include".
Instead of using macros for building examples and utils, use a for loop.
Include cmake's GNUInstallDirs to automatically correctly populate
installation dir variables, instead of doing it manually.

CMakeLists.txt

@@ -1,22 +1,19 @@
-cmake_minimum_required(VERSION 3.0.2)
+cmake_minimum_required(VERSION 3.1)
 
-project("TinyALSA" C)
+execute_process(COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/scripts/version.sh -s print
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    OUTPUT_VARIABLE TINYALSA_VERSION)
 
+project("TinyALSA" VERSION ${TINYALSA_VERSION} LANGUAGES C)
+
+# Options
+option(BUILD_SHARED_LIBS "Build shared libraries" ON)
 option(TINYALSA_USES_PLUGINS "Whether or not to build with plugin support" OFF)
+option(TINYALSA_BUILD_EXAMPLES "Build examples" ON)
+option(TINYALSA_BUILD_UTILS "Build utility tools" ON)
 
-if (TINYALSA_USES_PLUGINS)
-    set (plugin_opt -DTINYALSA_USES_PLUGINS=1)
-endif (TINYALSA_USES_PLUGINS)
-
-set (HDRS
-    "include/tinyalsa/attributes.h"
-    "include/tinyalsa/version.h"
-    "include/tinyalsa/asoundlib.h"
-    "include/tinyalsa/pcm.h"
-    "include/tinyalsa/plugin.h"
-    "include/tinyalsa/mixer.h")
-
-set (SRCS
+# Library
+add_library("tinyalsa"
     "src/pcm.c"
     "src/pcm_hw.c"
     "src/pcm_plugin.c"
@@ -25,53 +22,68 @@ set (SRCS
     "src/mixer_hw.c"
     "src/mixer_plugin.c")
 
-add_library("tinyalsa" ${HDRS} ${SRCS})
-target_compile_options("tinyalsa" PRIVATE -Wall -Wextra -Werror -Wfatal-errors ${plugin_opt})
-target_include_directories("tinyalsa" PRIVATE "include")
+set_property(TARGET "tinyalsa" PROPERTY PUBLIC_HEADER
+    "include/tinyalsa/attributes.h"
+    "include/tinyalsa/version.h"
+    "include/tinyalsa/asoundlib.h"
+    "include/tinyalsa/pcm.h"
+    "include/tinyalsa/plugin.h"
+    "include/tinyalsa/mixer.h")
 
-macro(ADD_EXAMPLE EXAMPLE)
-    add_executable(${EXAMPLE} ${ARGN})
-    target_link_libraries(${EXAMPLE} "tinyalsa")
-    target_link_libraries(${EXAMPLE} "dl")
-    target_include_directories(${EXAMPLE} PRIVATE "include")
-endmacro(ADD_EXAMPLE EXAMPLE)
+set_target_properties("tinyalsa" PROPERTIES
+    VERSION ${TinyALSA_VERSION}
+    SOVERSION ${TinyALSA_VERSION_MAJOR})
 
-add_example("pcm-readi" "examples/pcm-readi.c")
-add_example("pcm-writei" "examples/pcm-writei.c")
+target_include_directories("tinyalsa" PUBLIC
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+    $<INSTALL_INTERFACE:include>)
+target_compile_definitions("tinyalsa" PRIVATE
+    $<$<BOOL:${TINYALSA_USES_PLUGINS}>:TINYALSA_USES_PLUGINS>)
+target_link_libraries("tinyalsa" PUBLIC ${CMAKE_DL_LIBS})
 
-macro(ADD_UTIL UTIL)
-    add_executable(${UTIL} ${ARGN})
-    target_link_libraries(${UTIL} PRIVATE "tinyalsa")
-    target_link_libraries(${UTIL} PRIVATE "dl")
-    target_compile_options(${UTIL} PRIVATE -Wall -Wextra -Werror -Wfatal-errors)
-    target_include_directories(${UTIL} PRIVATE "include")
-endmacro(ADD_UTIL UTIL)
+# Examples
+if(TINYALSA_BUILD_EXAMPLES)
+    set(TINYALSA_EXAMPLES pcm-readi pcm-writei)
+else()
+    set(TINYALSA_EXAMPLES)
+endif()
 
-add_util("tinyplay" "utils/tinyplay.c")
-add_util("tinycap" "utils/tinycap.c")
-add_util("tinypcminfo" "utils/tinypcminfo.c")
-add_util("tinymix" "utils/tinymix.c")
-add_util("tinywavinfo" "utils/tinywavinfo.c")
+foreach(EXAMPLE IN LISTS TINYALSA_EXAMPLES)
+    add_executable("${EXAMPLE}" "examples/${EXAMPLE}.c")
+    target_link_libraries("${EXAMPLE}" PRIVATE "tinyalsa")
+endforeach()
 
+# Utilities
+if(TINYALSA_BUILD_UTILS)
+    set(TINYALSA_UTILS tinyplay tinycap tinypcminfo tinymix tinywavinfo)
+else()
+    set(TINYALSA_UTILS)
+endif()
+
+foreach(UTIL IN LISTS TINYALSA_UTILS)
+    add_executable("${UTIL}" "utils/${UTIL}.c")
+    target_link_libraries("${UTIL}" PRIVATE "tinyalsa")
+endforeach()
 target_link_libraries("tinywavinfo" PRIVATE m)
 
-install(FILES ${HDRS}
-    DESTINATION "include/tinyalsa")
+# Add C warning flags
+include(CheckCCompilerFlag)
+foreach(FLAG IN ITEMS -Wall -Wextra -Werror -Wfatal-errors)
+    string(TOUPPER "HAVE${FLAG}" HAVE_VAR)
+    string(REPLACE "-" "_" HAVE_VAR "${HAVE_VAR}")
+    check_c_compiler_flag("${FLAG}" "${HAVE_VAR}")
+    if("${${HAVE_VAR}}")
+        target_compile_options("tinyalsa" PRIVATE "${FLAG}")
+        foreach(UTIL IN LISTS TINYALSA_UTILS)
+            target_compile_options("${UTIL}" PRIVATE "${FLAG}")
+        endforeach()
+    endif()
+endforeach()
 
-if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
-    set(CMAKE_INSTALL_LIBDIR lib)
-endif()
-
-if(NOT DEFINED CMAKE_INSTALL_BINDIR)
-	set(CMAKE_INSTALL_BINDIR bin)
-endif()
-
-install(TARGETS "tinyalsa"
-                "tinyplay"
-                "tinycap"
-                "tinymix"
-                "tinypcminfo"
+# Install
+include(GNUInstallDirs)
+install(TARGETS "tinyalsa" ${TINYALSA_UTILS}
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
-    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR})
-
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})