[cmake-developers] ExternalProject and git clone

[Brad King]

On 09/10/2013 12:13 PM, David Cole wrote:
> I'll let Brad and Rob make the call about whether a patch with the 
> above comments incorporated should be merged to 'next' as is, or 
> whether it should be optionally enabled by a flag as well. I already 
> said I think we should preserve existing behavior, and only explicitly 
> do this new behavior if it's requested by a new parameter. I'm 
> conservative that way, and would prefer not to have existing folks who 
> are happy with the behavior become upset when they suddenly get a new 
> error just because they updated to a new version of CMake.

I think it should be explicitly enabled or disabled by an option:

 GIT_WORK_TREE_PRESERVE <0|1>

If the option is not given then default to ON if and only if:

 - The work tree is outside CMAKE_BINARY_DIR
 - NOT CMAKE_MINIMUM_REQUIRED_VERSION VERSION_LESS 2.8.13

assuming the change is introduced in 2.8.13.

This approach will preserve existing behavior, improve the default
moving forward, and allow an explicit specification.

-Brad