Change CMake from linking dynamic library to static library [duplicate] - cmake

Question

I want to statically link the libraries listed below:
set_target_properties(exec PROPERTIES LINK_SEARCH_START_STATIC 1)
set_target_properties(exec PROPERTIES LINK_SEARCH_END_STATIC 1)
set(CMAKE_FIND_LIBRARY_SUFFIXES .a ${CMAKE_FIND_LIBRARY_SUFFIXES})
find_library(SODIUM_LIB libsodium.a REQUIRED)
find_library(SSL_LIB libssl.a REQUIRED)
find_library(CRYPTO_LIB libcrypto.a REQUIRED)
find_library(DL_LIB libdl.a REQUIRED)
message(${SODIUM_LIB})
message(${SSL_LIB})
message(${CRYPTO_LIB})
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libgcc -static-libstdc++")
target_link_libraries(
exec
${SODIUM_LIB}
${SSL_LIB}
${CRYPTO_LIB}
${DL_LIB}
I do not want to add -static to CMAKE_EXE_LINKER_FLAGS, because in that case everything is linked static. CMake finds the static libraries:
/usr/local/lib/libsodium.a
/usr/lib/x86_64-linux-gnu/libssl.a
/usr/lib/x86_64-linux-gnu/libcrypto.a
and it seems that everything is linked statically except libcrypto:
readelf -d exec
0x0000000000000001 (NEEDED) Shared library: [libcrypto.so.1.0.0]
0x0000000000000001 (NEEDED) Shared library: [libc.so.6]
0x0000000000000001 (NEEDED) Shared library: [ld-linux-x86-64.so.2]
How can I link libcrypto statically to my executable?

Answer 1

The CMake documentation starting with version 3.4 on the FindOpenSSL page says:
Set OPENSSL_USE_STATIC_LIBS to TRUE to look for static libraries.
(Assuming if they are found they will be used)
Example:
cmake_minimum_required(VERSION 3.4)
project(Foo)
set(SOURCE_FILES main.cpp)
set(OPENSSL_USE_STATIC_LIBS TRUE)
find_package(OpenSSL REQUIRED)
add_executable(${PROJECT_NAME} ${SOURCE_FILES})
target_link_libraries(${PROJECT_NAME} OpenSSL::Crypto)