Refactor: derive pkg-config info to link static libraries (#1998)

Author: xshthkr

src/CMakeLists.txt

@@ -62,13 +62,11 @@ endif(HAVE_LIB_RT)
 # We need extra libraries on Windows
 if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
   target_link_libraries(benchmark PRIVATE shlwapi)
-  set(BENCHMARK_PRIVATE_LINK_LIBRARIES -lShlwapi)
 endif()
 
 # We need extra libraries on Solaris
 if(${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
   target_link_libraries(benchmark PRIVATE kstat)
-  set(BENCHMARK_PRIVATE_LINK_LIBRARIES -lkstat)
 endif()
 
 if (NOT BUILD_SHARED_LIBS)
@@ -110,6 +108,20 @@ write_basic_package_version_file(
   "${version_config}" VERSION ${GENERIC_LIB_VERSION} COMPATIBILITY SameMajorVersion
 )
 
+# Derive private link libraries from target
+if(NOT BUILD_SHARED_LIBS)
+  get_target_property(LINK_LIBS benchmark LINK_LIBRARIES)
+  if(LINK_LIBS)
+    set(BENCHMARK_PRIVATE_LINK_LIBRARIES "")
+    foreach(LIB IN LISTS LINK_LIBS)
+      if(NOT TARGET "${LIB}" AND LIB MATCHES "^[a-zA-Z0-9_.-]+$")
+        list(APPEND BENCHMARK_PRIVATE_LINK_LIBRARIES "-l${LIB}")
+      endif()
+    endforeach()
+    string(JOIN " " BENCHMARK_PRIVATE_LINK_LIBRARIES ${BENCHMARK_PRIVATE_LINK_LIBRARIES})
+  endif()
+endif()
+
 configure_file("${PROJECT_SOURCE_DIR}/cmake/benchmark.pc.in" "${pkg_config}" @ONLY)
 configure_file("${PROJECT_SOURCE_DIR}/cmake/benchmark_main.pc.in" "${pkg_config_main}" @ONLY)