cmake: separate installing and building (again)

CMakeLists.txt

@@ -1017,9 +1017,9 @@ if("${ZIG_EXECUTABLE}" STREQUAL "")
     WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
   )
   if (WIN32)
-    set(ZIG_EXECUTABLE "${zig2_BINARY_DIR}/zig2.exe")
+    set(ZIG_EXECUTABLE "${CMAKE_BINARY_DIR}/zig2.exe")
   else()
-    set(ZIG_EXECUTABLE "${zig2_BINARY_DIR}/zig2")
+    set(ZIG_EXECUTABLE "${CMAKE_BINARY_DIR}/zig2")
   endif()
 else()
   add_custom_command(
@@ -1045,15 +1045,8 @@ elseif(MINGW)
   target_link_libraries(zig2 ntdll)
 endif()
 
-# Dummy install command so that the "install" target is not missing.
-# This is redundant from the "stage3" custom target below.
-if(NOT ZIG_SKIP_INSTALL_LIB_FILES)
-  install(FILES "lib/compiler_rt.zig" DESTINATION "lib/zig")
-endif()
-
-set(ZIG_INSTALL_ARGS "build"
+set(ZIG_BUILD_ARGS "build"
     --zig-lib-dir "${CMAKE_SOURCE_DIR}/lib"
-    --prefix "${CMAKE_INSTALL_PREFIX}"
     "-Dconfig_h=${ZIG_CONFIG_H_OUT}"
     "-Denable-llvm"
     "-Denable-stage1"
@@ -1067,8 +1060,14 @@ set(ZIG_INSTALL_ARGS "build"
 )
 
 add_custom_target(stage3 ALL
-    COMMAND zig2 ${ZIG_INSTALL_ARGS}
+    COMMAND zig2 ${ZIG_BUILD_ARGS}
     DEPENDS zig2
     COMMENT STATUS "Building stage3"
     WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
 )
+
+install(CODE "set(ZIG_EXECUTABLE \"${ZIG_EXECUTABLE}\")")
+install(CODE "set(ZIG_BUILD_ARGS \"${ZIG_BUILD_ARGS}\")")
+install(CODE "set(CMAKE_INSTALL_PREFIX \"${CMAKE_INSTALL_PREFIX}\")")
+install(CODE "set(CMAKE_SOURCE_DIR \"${CMAKE_SOURCE_DIR}\")")
+install(SCRIPT "${CMAKE_SOURCE_DIR}/cmake/install.cmake")

cmake/install.cmake

@@ -0,0 +1,24 @@
+set(ZIG_INSTALL_ARGS ${ZIG_BUILD_ARGS} --prefix "${CMAKE_INSTALL_PREFIX}")
+execute_process(COMMAND "${ZIG_EXECUTABLE}" ${ZIG_INSTALL_ARGS} WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}" RESULT_VARIABLE _result)
+
+if(_result)
+    message("::")
+    message(":: ERROR: ${_result}")
+    message(":: (execute_process)")
+
+    list(JOIN ZIG_INSTALL_ARGS " " s_INSTALL_LIBSTAGE2_ARGS)
+    message("::")
+    message(":: argv: ${ZIG_EXECUTABLE} ${s_INSTALL_LIBSTAGE2_ARGS}")
+
+    set(_args ${ZIG_EXECUTABLE} ${ZIG_INSTALL_ARGS})
+    list(LENGTH _args _len)
+    math(EXPR _len "${_len} - 1")
+    message("::")
+    foreach(_i RANGE 0 ${_len})
+        list(GET _args ${_i} _arg)
+        message(":: argv[${_i}]: ${_arg}")
+    endforeach()
+
+    message("::")
+    message(FATAL_ERROR)
+endif()