[CMake] Make the bindir and libdir arguments to set_output_directory optional

[john.brawn]

Summary

When building a plugin against an installed LLVM toolchain using add_llvm_loadable_module (in the documented manner) doesn't work as nothing sets the *_OUTPUT_INTDIR variables causing an error when set_output_directory is called. Making those arguments optional (causing the default output directory to be used) fixes this.

[beanz]

cmake/modules/AddLLVM.cmake

206

I think that a better way to do this would be to use cmake_parse_arguments and make output and bind directory be single value options. Then if one isn't specified it is ignored.

I also think it would be cleaner if set_target_properties were only called if the corresponding value is set.

[chapuni]

LGTM, as a step.

That said, I think set_output_directory may be rewritten.
It may be dedicated to set outdir along LLVM_*_OUTPUT_INTDIR, or reset outdir.

[john.brawn]

cmake/modules/AddLLVM.cmake

206

I had thought of using cmake_parse_arguments, but decided against it as it would involve changing how set_output_directory is called. It's only called in three places though, so actually that won't be too much trouble. I'll give it a go.

[john.brawn]

I've gone with the suggestion of using cmake_parse_arguments. I haven't gone for calling set_target_properties is the argument is set, instead of the check at the start, mainly as I'm not sure how moddir would be handled if that were done.

[beanz]

I think all you need to do for handling unset values is something like this:

diff --git a/cmake/modules/AddLLVM.cmake b/cmake/modules/AddLLVM.cmake
index 993bc35..63047e6 100644
--- a/cmake/modules/AddLLVM.cmake
+++ b/cmake/modules/AddLLVM.cmake
@@ -211,17 +211,33 @@ function(set_output_directory target)
   if(NOT "${CMAKE_CFG_INTDIR}" STREQUAL ".")
     foreach(build_mode ${CMAKE_CONFIGURATION_TYPES})
       string(TOUPPER "${build_mode}" CONFIG_SUFFIX)
-      string(REPLACE ${CMAKE_CFG_INTDIR} ${build_mode} bi ${ARG_BINDIR})
-      string(REPLACE ${CMAKE_CFG_INTDIR} ${build_mode} li ${ARG_LIBDIR})
-      string(REPLACE ${CMAKE_CFG_INTDIR} ${build_mode} mi ${moddir})
-      set_target_properties(${target} PROPERTIES "RUNTIME_OUTPUT_DIRECTORY_${CONFIG_SUFFIX}" ${bi})
-      set_target_properties(${target} PROPERTIES "ARCHIVE_OUTPUT_DIRECTORY_${CONFIG_SUFFIX}" ${li})
-      set_target_properties(${target} PROPERTIES "LIBRARY_OUTPUT_DIRECTORY_${CONFIG_SUFFIX}" ${mi})
+      if(ARG_BINDIR)
+        string(REPLACE ${CMAKE_CFG_INTDIR} ${build_mode} bi ${ARG_BINDIR})
+        set_target_properties(${target} PROPERTIES "RUNTIME_OUTPUT_DIRECTORY_${CONFIG_SUFFIX}" ${bi})
+      endif()
+
+      if(ARG_LIBDIR)
+        string(REPLACE ${CMAKE_CFG_INTDIR} ${build_mode} li ${ARG_LIBDIR})
+        set_target_properties(${target} PROPERTIES "ARCHIVE_OUTPUT_DIRECTORY_${CONFIG_SUFFIX}" ${li})
+      endif()
+
+      if(moddir)
+        string(REPLACE ${CMAKE_CFG_INTDIR} ${build_mode} mi ${moddir})
+        set_target_properties(${target} PROPERTIES "LIBRARY_OUTPUT_DIRECTORY_${CONFIG_SUFFIX}" ${mi})
+      endif()
     endforeach()
   else()
-    set_target_properties(${target} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${ARG_BINDIR})
-    set_target_properties(${target} PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${ARG_LIBDIR})
-    set_target_properties(${target} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${moddir})
+    if(ARG_BINDIR)
+      set_target_properties(${target} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${ARG_BINDIR})
+    endif()
+
+    if(ARG_LIBDIR)
+      set_target_properties(${target} PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${ARG_LIBDIR})
+    endif()
+
+    if(moddir)
+      set_target_properties(${target} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${moddir})
+    endif()
   endif()
 endfunction()

I have one other comment below.

Thanks,
-Chris

cmake/modules/AddLLVM.cmake

197

Two things here.

1. You need another empty string before ${ARGN} otherwise the first argument from ARGN will be treated as your multi-variable option list.

2. Maybe make the options more explicitly worded now that they are externally facing. I'd suggest BINARY_DIR and LIBRARY_DIR.

[john.brawn]

Made the suggested changes to the handling of unset arguments.

[beanz]

LGTM. Thanks!

-Chris

cmake/modules/AddLLVM.cmake

if(NOT LLVM_NO_DEAD_STRIP)
       endif()
     endif()
   endif()
 endfunction(add_link_opts)
 
 # Set each output directory according to ${CMAKE_CONFIGURATION_TYPES}.
 # Note: Don't set variables CMAKE_*_OUTPUT_DIRECTORY any more,
 # or a certain builder, for eaxample, msbuild.exe, would be confused.
-function(set_output_directory target bindir libdir)
+function(set_output_directory target)
+  # This function takes bindir and libdir arguments but allows them to be unset,
+  # in which case the default output directory is used (this is useful when
+  # using AddLLVM.cmake from an installed LLVM toolchain as they will end up
+  # being unset in that case). This is done by leaving those arguments off the
+  # argument list and instead getting them from ARGV.
+  if(${ARGC} LESS 3)
+    return()
+  endif()
+  set(bindir ${ARGV1})
+  set(libdir ${ARGV2})
   # Do nothing if *_OUTPUT_INTDIR is empty.
   if("${bindir}" STREQUAL "")
     return()
   endif()
 
   # moddir -- corresponding to LIBRARY_OUTPUT_DIRECTORY.
   # It affects output of add_library(MODULE).
   if(WIN32 OR CYGWIN)