[CMake] Strange behaviour of STREQUAL with a variable containing only "type"

[Nils Gladitz]

On 17.04.2015 13:09, Sylvain Doremus wrote:
> I have a strange output, related to the minimal CMakeLists.txt that I've provided with this email.
> My CMake version is 3.2.1, on Windows Seven SP1, the tested generators are Visual Studio 10 2010 and Visual Studio 10 2010 Win64.
>
> Here is the output I've got:
>
> TestFolder/type
>
> TestFolder
> TestFolder/type
> Configuring done
>
> Is it normal? Or is it a bug?If it is normal, can someone explain me why it is?

It is expected if "type" itself is a variable (set by some module 
evaluated by project()).

e.g. given:
   set(TEST_FOLDER type)

The following if():
   if(${TEST_FOLDER} STREQUAL "")

After expansion:
   if(test STREQUAL "")

If test is a variable set to "" this becomes equivalent to:
   if("" STREQUAL "")

If test is not defined as a variable this is instead equivalent to:
   if("test" STREQUAL "")

Quoting prevents cmake from dereferencing variables like this if CMP0054 
[1] is set to NEW.
CMP0054 is set to NEW for you since you require a cmake version >= 3.1.

Nils

[1] http://www.cmake.org/cmake/help/v3.2/policy/CMP0054.html