cmake: Fix the build on Windows.

src/threads/CMakeLists.txt

@@ -53,73 +53,75 @@ include_directories(
   ${LIBSSH_THREADS_PRIVATE_INCLUDE_DIRS}
 )
 
-add_library(${LIBSSH_THREADS_SHARED_LIBRARY} SHARED ${libssh_threads_SRCS})
+if (libssh_threads_SRCS)
+    add_library(${LIBSSH_THREADS_SHARED_LIBRARY} SHARED ${libssh_threads_SRCS})
 
-target_link_libraries(${LIBSSH_THREADS_SHARED_LIBRARY} ${LIBSSH_THREADS_LINK_LIBRARIES})
+    target_link_libraries(${LIBSSH_THREADS_SHARED_LIBRARY} ${LIBSSH_THREADS_LINK_LIBRARIES})
 
-set_target_properties(
-  ${LIBSSH_THREADS_SHARED_LIBRARY}
-    PROPERTIES
-      VERSION
-        ${LIBRARY_VERSION}
-      SOVERSION
-        ${LIBRARY_SOVERSION}
-      OUTPUT_NAME
-        ssh_threads
-      DEFINE_SYMBOL
-        LIBSSH_EXPORTS
-)
-
-if (WITH_VISIBILITY_HIDDEN)
-  set_target_properties(${LIBSSH_THREADS_SHARED_LIBRARY} PROPERTIES COMPILE_FLAGS "-fvisibility=hidden")
-endif (WITH_VISIBILITY_HIDDEN)
-
-install(
-  TARGETS
-    ${LIBSSH_THREADS_SHARED_LIBRARY}
-  RUNTIME DESTINATION ${BIN_INSTALL_DIR}
-  LIBRARY DESTINATION ${LIB_INSTALL_DIR}
-  ARCHIVE DESTINATION ${LIB_INSTALL_DIR}
-  COMPONENT libraries
-)
-
-if (WITH_STATIC_LIB)
-  add_library(${LIBSSH_THREADS_STATIC_LIBRARY} STATIC ${libssh_threads_SRCS})
-
-  if (MSVC)
-    set(OUTPUT_SUFFIX static)
-  else (MSVC)
-    set(OUTPUT_SUFFIX )
-  endif (MSVC)
-
-  set_target_properties(
-    ${LIBSSH_THREADS_STATIC_LIBRARY}
-      PROPERTIES
-        VERSION
-          ${LIBRARY_VERSION}
-        SOVERSION
-          ${LIBRARY_SOVERSION}
-        OUTPUT_NAME
-          ssh_threads
-        ARCHIVE_OUTPUT_DIRECTORY
-          ${CMAKE_CURRENT_BINARY_DIR}/${OUTPUT_SUFFIX}
-  )
-
-  if (WIN32)
     set_target_properties(
-        ${LIBSSH_THREADS_STATIC_LIBRARY}
-            PROPERTIES
-                COMPILE_FLAGS
-                    "-DLIBSSH_STATIC"
-  )
-  endif (WIN32)
+      ${LIBSSH_THREADS_SHARED_LIBRARY}
+        PROPERTIES
+          VERSION
+            ${LIBRARY_VERSION}
+          SOVERSION
+            ${LIBRARY_SOVERSION}
+          OUTPUT_NAME
+            ssh_threads
+          DEFINE_SYMBOL
+            LIBSSH_EXPORTS
+    )
 
-  install(
-    TARGETS
-      ${LIBSSH_THREADS_STATIC_LIBRARY}
-    DESTINATION
-      ${LIB_INSTALL_DIR}/${OUTPUT_SUFFIX}
-    COMPONENT
-      libraries
-  )
-endif (WITH_STATIC_LIB)
+    if (WITH_VISIBILITY_HIDDEN)
+      set_target_properties(${LIBSSH_THREADS_SHARED_LIBRARY} PROPERTIES COMPILE_FLAGS "-fvisibility=hidden")
+    endif (WITH_VISIBILITY_HIDDEN)
+
+    install(
+      TARGETS
+        ${LIBSSH_THREADS_SHARED_LIBRARY}
+      RUNTIME DESTINATION ${BIN_INSTALL_DIR}
+      LIBRARY DESTINATION ${LIB_INSTALL_DIR}
+      ARCHIVE DESTINATION ${LIB_INSTALL_DIR}
+      COMPONENT libraries
+    )
+
+    if (WITH_STATIC_LIB)
+      add_library(${LIBSSH_THREADS_STATIC_LIBRARY} STATIC ${libssh_threads_SRCS})
+
+      if (MSVC)
+        set(OUTPUT_SUFFIX static)
+      else (MSVC)
+        set(OUTPUT_SUFFIX )
+      endif (MSVC)
+
+      set_target_properties(
+        ${LIBSSH_THREADS_STATIC_LIBRARY}
+          PROPERTIES
+            VERSION
+              ${LIBRARY_VERSION}
+            SOVERSION
+              ${LIBRARY_SOVERSION}
+            OUTPUT_NAME
+              ssh_threads
+            ARCHIVE_OUTPUT_DIRECTORY
+              ${CMAKE_CURRENT_BINARY_DIR}/${OUTPUT_SUFFIX}
+      )
+
+      if (WIN32)
+        set_target_properties(
+            ${LIBSSH_THREADS_STATIC_LIBRARY}
+                PROPERTIES
+                    COMPILE_FLAGS
+                        "-DLIBSSH_STATIC"
+      )
+      endif (WIN32)
+
+      install(
+        TARGETS
+          ${LIBSSH_THREADS_STATIC_LIBRARY}
+        DESTINATION
+          ${LIB_INSTALL_DIR}/${OUTPUT_SUFFIX}
+        COMPONENT
+          libraries
+      )
+    endif (WITH_STATIC_LIB)
+endif (libssh_threads_SRCS)