Obtained from:	https://github.com/json-c/json-c/commit/8b511c402b73d1d8b195991891c8d44859cb57ec
		https://github.com/json-c/json-c/commit/22870ac2bd4cfdd135887ecc8cbbe02e7ef0c34e
		https://github.com/json-c/json-c/commit/4f43a077a497f94214645ce9763247ec085e2094

--- CMakeLists.txt.orig	2020-04-19 03:39:09 UTC
+++ CMakeLists.txt
@@ -65,6 +65,7 @@ include(GNUInstallDirs)
 include(CMakePackageConfigHelpers)
 
 option(BUILD_SHARED_LIBS  "Default to building shared libraries" ON)
+option(BUILD_STATIC_LIBS  "Default to building static libraries" ON)
 
 # Generate a release merge and test it to verify the correctness of republishing the package.
 ADD_CUSTOM_TARGET(distcheck
@@ -299,7 +300,7 @@ if ($ENV{VALGRIND})
 endif()
 
 set(JSON_C_PUBLIC_HEADERS
-    ${PROJECT_BINARY_DIR}/config.h
+    # Note: config.h is _not_ included here
     ${PROJECT_BINARY_DIR}/json_config.h
 
     ${PROJECT_SOURCE_DIR}/json.h
@@ -383,7 +384,7 @@ add_library(${PROJECT_NAME}
 set_target_properties(${PROJECT_NAME} PROPERTIES
     VERSION 5.0.0
     SOVERSION 5)
-
+list(APPEND CMAKE_TARGETS ${PROJECT_NAME})
 # If json-c is used as subroject it set to target correct interface -I flags and allow
 # to build external target without extra include_directories(...)
 target_include_directories(${PROJECT_NAME}
@@ -392,7 +393,22 @@ target_include_directories(${PROJECT_NAME}
         $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}>
 )
 
-install(TARGETS ${PROJECT_NAME}
+# Allow to build static and shared libraries at the same time
+if (BUILD_STATIC_LIBS AND BUILD_SHARED_LIBS)
+    set(STATIC_LIB ${PROJECT_NAME}-static)
+    add_library(${STATIC_LIB} STATIC
+        ${JSON_C_SOURCES}
+        ${JSON_C_HEADERS}
+    )
+
+    # rename the static library
+    set_target_properties(${STATIC_LIB} PROPERTIES
+        OUTPUT_NAME ${PROJECT_NAME}
+    )
+    list(APPEND CMAKE_TARGETS ${STATIC_LIB})
+endif ()
+
+install(TARGETS ${CMAKE_TARGETS}
     EXPORT ${PROJECT_NAME}-targets
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}