[llvm] r242120 - [CMake] Unbreak add_llvm_external_project when external projects are specified.

[Brad King]

On 07/14/2015 11:57 AM, Chris Bieneman wrote:
> If PATH does have some impact on how the value is expanded

There is a subtle case where it does affect the value that was only
documented recently:

 http://www.cmake.org/cmake/help/v3.3/command/set.html
 "It is possible for the cache entry to exist prior to the call but
  have no type set if it was created on the cmake(1) command line
  by a user through the -D<var>=<value> option without specifying a
  type. In this case the set command will add the type.
  Furthermore, if the <type> is PATH or FILEPATH and the
  <value> provided on the command line is a relative path, then the
  set command will treat the path as relative to the current
  working directory and convert it to an absolute path."

It has been that way for a long time and is implemented here:

 http://www.cmake.org/gitweb?p=cmake.git;a=blob;f=Source/cmMakefile.cxx;hb=v3.3.0-rc4#l1754

but the above documentation was only added as of 3.3.

-Brad