commit c64797fa94de29ef3f5f9c940273036c9ebf64ee
author Brad King <brad.king@kitware.com> Tue Oct 09 08:25:16 2018 -0400
committer Brad King <brad.king@kitware.com> Tue Oct 09 08:55:54 2018 -0400
tree 8d87ddb1739d2adb3fbcd0a179ce577bfabf5edc
parent fd02538974dd952a8639d371c2c0067d30d5469a

FindBISON: Fix "multiple rules generate" error on VERBOSE output

When `BISON_TARGET` is called with both

    VERBOSE <extra-file> REPORT_FILE <file>

we add a custom command to copy `<file>` to `<extra-file>`.  The change
in commit v3.7.1~10^2 (FindBISON: Do not rebuild every time when not
VERBOSE, 2016-11-14) incorrectly listed the extra file as an output of
the main bison invocation custom command, but it is actually produced by
the separate copy command.  Fix the logic to always generate `<file>` as
an output of the bison command and `<extra-file>` as an output of the
copy command.

Fixes: #18433

Modules/FindBISON.cmake

diff --git a/Modules/FindBISON.cmake b/Modules/FindBISON.cmake
index d684ccd..2000f7f 100644
--- a/Modules/FindBISON.cmake
+++ b/Modules/FindBISON.cmake
@@ -149,17 +149,25 @@
       set(BISON_TARGET_verbose_file "${ReportFile}")
       list(APPEND BISON_TARGET_cmdopt "--report-file=${BISON_TARGET_verbose_file}")
     endif()
+    if(NOT IS_ABSOLUTE "${BISON_TARGET_verbose_file}")
+      set(BISON_TARGET_verbose_file "${CMAKE_CURRENT_SOURCE_DIR}/${BISON_TARGET_verbose_file}")
+    endif()
   endmacro()
 
   # internal macro
   # adds a custom command and sets
-  #   BISON_TARGET_cmdopt, BISON_TARGET_verbose_file, BISON_TARGET_extraoutputs
+  #   BISON_TARGET_cmdopt, BISON_TARGET_extraoutputs
   macro(BISON_TARGET_option_verbose Name BisonOutput filename)
     list(APPEND BISON_TARGET_cmdopt "--verbose")
-    list(APPEND BISON_TARGET_extraoutputs
+    list(APPEND BISON_TARGET_outputs
       "${BISON_TARGET_verbose_file}")
     if (NOT "${filename}" STREQUAL "")
-      add_custom_command(OUTPUT ${filename}
+      if(IS_ABSOLUTE "${filename}")
+        set(BISON_TARGET_verbose_extra_file "${filename}")
+      else()
+        set(BISON_TARGET_verbose_extra_file "${CMAKE_CURRENT_SOURCE_DIR}/${filename}")
+      endif()
+      add_custom_command(OUTPUT ${BISON_TARGET_verbose_extra_file}
         COMMAND ${CMAKE_COMMAND} -E copy
         "${BISON_TARGET_verbose_file}"
         "${filename}"
@@ -167,10 +175,10 @@
         DEPENDS
         "${BISON_TARGET_verbose_file}"
         COMMENT "[BISON][${Name}] Copying bison verbose table to ${filename}"
-        WORKING_DIRECTORY ${CMAKE_SOURCE_DIR})
-      set(BISON_${Name}_VERBOSE_FILE ${filename})
+        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
       list(APPEND BISON_TARGET_extraoutputs
-        "${filename}")
+        "${BISON_TARGET_verbose_extra_file}")
+      unset(BISON_TARGET_verbose_extra_file)
     endif()
   endmacro()
 
@@ -226,7 +234,6 @@
       list(APPEND BISON_TARGET_outputs "${BISON_TARGET_output_header}")
 
       add_custom_command(OUTPUT ${BISON_TARGET_outputs}
-        ${BISON_TARGET_extraoutputs}
         COMMAND ${BISON_EXECUTABLE} ${BISON_TARGET_cmdopt} -o ${BisonOutput} ${BisonInput}
         VERBATIM
         DEPENDS ${BisonInput}