这是我的CMakeLists.txt：

cmake_minimum_required(VERSION 3.14)

project(testlib C)

set(CMAKE_C_STANDARD 99)


include_directories(/usr/local/include/)
find_library(iconv_lib iconv)
add_executable(testlib  library.c)
target_link_libraries(testlib libiconv.a)

此文件夹/usr/local/include/中的文件：

iconv.h  localcharset.h

CMake报告错误：

====================[ Build | testlib | Debug ]=================================
D:\.CLion2019.2\system\cygwin_cmake\bin\cmake.exe --build /cygdrive/d/project/c/testlib/cmake-build-debug --target testlib -- -j 4
Scanning dependencies of target testlib
[ 50%] Building C object CMakeFiles/testlib.dir/library.c.o
[100%] Linking C executable testlib.exe
/usr/lib/gcc/x86_64-pc-cygwin/7.4.0/../../../../x86_64-pc-cygwin/bin/ld: cannot find -liconv
collect2: error: ld returned 1 exit status
make[3]: *** [CMakeFiles/testlib.dir/build.make:84: testlib.exe] Error 1
make[2]: *** [CMakeFiles/Makefile2:76: CMakeFiles/testlib.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/testlib.dir/rule] Error 2
make: *** [Makefile:118: testlib] Error 2