CMake: Find librt

Change-Id: Ibc39ba7a385146cd0428b78e12a793f0ddbfae91
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>

cmake/FindWrapRt.cmake

@@ -0,0 +1,27 @@
+include(CheckCXXSourceCompiles)
+
+find_library(LIBRT rt)
+
+set(_libraries "${CMAKE_REQUIRED_LIBRARIES}")
+if(LIBRT_FOUND)
+    list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBRT}")
+endif()
+
+check_cxx_source_compiles("
+#include <unistd.h>
+#include <time.h>
+
+int main(int argc, char *argv[]) {
+    timespec ts; clock_gettime(CLOCK_REALTIME, &ts);
+}" HAVE_GETTIME)
+
+set(CMAKE_REQUIRED_LIBRARIES "${_libraries}")
+unset(_libraries)
+
+add_library(WrapRt INTERFACE)
+if (LIBRT_FOUND)
+    target_link_libraries(WrapRt INTERFACE "${LIBRT}")
+endif()
+
+set(WrapRt_FOUND "${HAVE_GETTIME}")
+

src/corelib/CMakeLists.txt

@@ -231,6 +231,7 @@ add_qt_module(Core
         tools/qvsnprintf.cpp
     LIBRARIES
         WrapDoubleConversion
+        WrapRt
         tinycbor Threads::Threads ZLIB::ZLIB
         QtHarfBuzz
     PUBLIC_LIBRARIES Qt::Platform

src/corelib/configure.cmake

@@ -18,6 +18,8 @@ find_package(Libsystemd)
 set_package_properties(Libsystemd PROPERTIES TYPE OPTIONAL)
 find_package(Atomic)
 set_package_properties(Atomic PROPERTIES TYPE OPTIONAL)
+find_package(WrapRt)
+set_package_properties(WrapRt PROPERTIES TYPE OPTIONAL)
 find_package(PCRE2)
 set_package_properties(PCRE2 PROPERTIES TYPE REQUIRED)
 
@@ -340,7 +342,7 @@ closelog();
 
 qt_feature("clock_gettime" PRIVATE
     LABEL "clock_gettime()"
-    CONDITION UNIX AND libs.librt OR FIXME
+    CONDITION UNIX AND WrapRt_FOUND
 )
 qt_feature("clock_monotonic" PUBLIC
     LABEL "POSIX monotonic clock"

util/cmake/configurejson2cmake.py

@@ -67,6 +67,7 @@ def map_library(lib: str) -> Union[str, LibraryMapping, List[str]]:
        'libpng': 'PNG',
        'libpng': 'PNG',
        'libproxy': 'libproxy',
+       'librt': 'WrapRt',
        'libudev': 'Libudev',
        'opengl': LibraryMapping(package="OpenGL", resultVariable="OpenGL_OpenGL"),
        'openssl_headers': LibraryMapping(package="OpenSSL", resultVariable="OPENSSL_INCLUDE_DIR", appendFoundSuffix=False),