From e6736d1baa5836fa4e39bc06e4569df8c1562635 Mon Sep 17 00:00:00 2001
From: Ivan Le Lann <ivan.lelann@gmail.com>
Date: Sat, 2 Oct 2021 15:26:17 +0200
Subject: [PATCH] Support CMake none targets

When trying to import rapidjson with for exemple :
fetchcontent_declare(rapidjson GIT_REPOSITORY https://github.com/Tencent/rapidjson.git)

if your CMake/Clang is "bare metal", exemple given :

set(CMAKE_SYSTEM_NAME none)
set(CMAKE_SYSTEM_PROCESSOR x86_64)
set(CMAKE_C_COMPILER_TARGET x86_64-elf-none)
set(CMAKE_CXX_COMPILER_TARGET x86_64-elf-none)

CMake fails to process CMakeLists.txt because of the switch on UNIX/CYGWIN/WIN32 for install directory.

Error is:

CMake Error at cmake-build-debug-clang/_deps/rapidjson-src/CMakeLists.txt:244 (INSTALL):
  INSTALL FILES given no DESTINATION!
---
 CMakeLists.txt | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index dc2072a9..bdfdd677 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -241,8 +241,10 @@ INSTALL(FILES "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/${PROJECT_NAM
         DESTINATION ${CMAKECONFIG_INSTALL_DIR} )
 
 # Install files
-INSTALL(FILES
-    ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake
-    ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
-    DESTINATION "${CMAKE_INSTALL_DIR}"
-    COMPONENT dev)
+IF(CMAKE_INSTALL_DIR)
+  INSTALL(FILES
+      ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake
+      ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
+      DESTINATION "${CMAKE_INSTALL_DIR}"
+      COMPONENT dev)
+ENDIF()