FindFLEX: Add policy CMP0098 to run flex in build tree

1 files changed, 54 insertions, 19 deletions

diff --git a/Modules/FindFLEX.cmake b/Modules/FindFLEX.cmake
index d22b7ec..90e5f86 100644
--- a/Modules/FindFLEX.cmake
+++ b/Modules/FindFLEX.cmake
@@ -142,8 +142,6 @@ if(FLEX_EXECUTABLE)
   #============================================================
   #
   macro(FLEX_TARGET Name Input Output)
-    set(FLEX_TARGET_outputs "${Output}")
-    set(FLEX_EXECUTABLE_opts "")
 
     set(FLEX_TARGET_PARAM_OPTIONS)
     set(FLEX_TARGET_PARAM_ONE_VALUE_KEYWORDS
@@ -165,31 +163,68 @@ if(FLEX_EXECUTABLE)
     if(NOT "${FLEX_TARGET_ARG_UNPARSED_ARGUMENTS}" STREQUAL "")
       message(SEND_ERROR ${FLEX_TARGET_usage})
     else()
+
+      cmake_policy(GET CMP0098 _flex_CMP0098
+          PARENT_SCOPE # undocumented, do not use outside of CMake
+        )
+      set(_flex_INPUT "${Input}")
+      if("x${_flex_CMP0098}x" STREQUAL "xNEWx")
+        set(_flex_WORKING_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+        if(NOT IS_ABSOLUTE "${_flex_INPUT}")
+          set(_flex_INPUT "${CMAKE_CURRENT_SOURCE_DIR}/${_flex_INPUT}")
+        endif()
+      else()
+        set(_flex_WORKING_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+      endif()
+      unset(_flex_CMP0098)
+
+      set(_flex_OUTPUT "${Output}")
+      if(NOT IS_ABSOLUTE ${_flex_OUTPUT})
+        set(_flex_OUTPUT "${_flex_WORKING_DIR}/${_flex_OUTPUT}")
+      endif()
+      set(_flex_TARGET_OUTPUTS "${_flex_OUTPUT}")
+
+      set(_flex_EXE_OPTS "")
       if(NOT "${FLEX_TARGET_ARG_COMPILE_FLAGS}" STREQUAL "")
-        set(FLEX_EXECUTABLE_opts "${FLEX_TARGET_ARG_COMPILE_FLAGS}")
-        separate_arguments(FLEX_EXECUTABLE_opts)
+        set(_flex_EXE_OPTS "${FLEX_TARGET_ARG_COMPILE_FLAGS}")
+        separate_arguments(_flex_EXE_OPTS)
       endif()
+
+      set(_flex_OUTPUT_HEADER "")
       if(NOT "${FLEX_TARGET_ARG_DEFINES_FILE}" STREQUAL "")
-        list(APPEND FLEX_TARGET_outputs "${FLEX_TARGET_ARG_DEFINES_FILE}")
-        list(APPEND FLEX_EXECUTABLE_opts --header-file=${FLEX_TARGET_ARG_DEFINES_FILE})
+        set(_flex_OUTPUT_HEADER "${FLEX_TARGET_ARG_DEFINES_FILE}")
+        if(IS_ABSOLUTE "${_flex_OUTPUT_HEADER}")
+          set(_flex_OUTPUT_HEADER_ABS "${_flex_OUTPUT_HEADER}")
+        else()
+          set(_flex_OUTPUT_HEADER_ABS "${_flex_WORKING_DIR}/${_flex_OUTPUT_HEADER}")
+        endif()
+        list(APPEND _flex_TARGET_OUTPUTS "${_flex_OUTPUT_HEADER_ABS}")
+        list(APPEND _flex_EXE_OPTS --header-file=${_flex_OUTPUT_HEADER_ABS})
       endif()
 
-      add_custom_command(OUTPUT ${FLEX_TARGET_outputs}
-        COMMAND ${FLEX_EXECUTABLE} ${FLEX_EXECUTABLE_opts} -o${Output} ${Input}
+      get_filename_component(_flex_EXE_NAME_WE "${FLEX_EXECUTABLE}" NAME_WE)
+      add_custom_command(OUTPUT ${_flex_TARGET_OUTPUTS}
+        COMMAND ${FLEX_EXECUTABLE} ${_flex_EXE_OPTS} -o${_flex_OUTPUT} ${_flex_INPUT}
         VERBATIM
-        DEPENDS ${Input}
-        COMMENT "[FLEX][${Name}] Building scanner with flex ${FLEX_VERSION}"
-        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+        DEPENDS ${_flex_INPUT}
+        COMMENT "[FLEX][${Name}] Building scanner with ${_flex_EXE_NAME_WE} ${FLEX_VERSION}"
+        WORKING_DIRECTORY ${_flex_WORKING_DIR})
 
       set(FLEX_${Name}_DEFINED TRUE)
-      set(FLEX_${Name}_OUTPUTS ${Output})
-      set(FLEX_${Name}_INPUT ${Input})
-      set(FLEX_${Name}_COMPILE_FLAGS ${FLEX_EXECUTABLE_opts})
-      if("${FLEX_TARGET_ARG_DEFINES_FILE}" STREQUAL "")
-        set(FLEX_${Name}_OUTPUT_HEADER "")
-      else()
-        set(FLEX_${Name}_OUTPUT_HEADER ${FLEX_TARGET_ARG_DEFINES_FILE})
-      endif()
+      set(FLEX_${Name}_OUTPUTS ${_flex_TARGET_OUTPUTS})
+      set(FLEX_${Name}_INPUT ${_flex_INPUT})
+      set(FLEX_${Name}_COMPILE_FLAGS ${_flex_EXE_OPTS})
+      set(FLEX_${Name}_OUTPUT_HEADER ${_flex_OUTPUT_HEADER})
+
+      unset(_flex_EXE_NAME_WE)
+      unset(_flex_EXE_OPTS)
+      unset(_flex_INPUT)
+      unset(_flex_OUTPUT)
+      unset(_flex_OUTPUT_HEADER)
+      unset(_flex_OUTPUT_HEADER_ABS)
+      unset(_flex_TARGET_OUTPUTS)
+      unset(_flex_WORKING_DIR)
+
     endif()
   endmacro()
   #============================================================