[cmake-developers] [CMake 0016133]: NO_DEFAULT_PATH is taken as a path when specified after the PATHS option.

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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https://public.kitware.com/Bug/view.php?id=16133 
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Reported By:                Alexis Wilke
Assigned To:                
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Project:                    CMake
Issue ID:                   16133
Category:                   CMake
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
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Date Submitted:             2016-05-31 20:27 EDT
Last Modified:              2016-05-31 20:27 EDT
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Summary:                    NO_DEFAULT_PATH is taken as a path when specified
after the PATHS option.
Description: 
I wanted to make sure that I could get a header from my environment (i.e. source
tree) first, then from the system if no specific version in the environment was
defined there. For this purpose, I used the NO_DEFAULT_PATH option as defined in
the documentation:

https://cmake.org/cmake/help/v3.5/command/find_path.html

However, the code would always return path "/usr/include" when I expect (in my
specific case) to see path "...path-to-source.../contrib/catch"

I found that by putting the NO_DEFAULT_PATH before the PATHS option, it worked
as I first expected. It seems to me, though, that it is not correct. There
should be a check and if a path defined after the PATHS option looks like a
flag, it should be taken as such and see it as the end of the list of PATHS or
HINTS.

Steps to Reproduce: 
The failing search looks like this:

FIND_PATH(CATCH_INCLUDE_DIR
    catch.hpp
    PATHS
        ${CMAKE_SOURCE_DIR}/contrib/catch 
        ${CMAKE_SOURCE_DIR}/contrib
    NO_DEFAULT_PATH
)

IF(NOT CATCH_INCLUDE_DIR)
    # Try again with default paths as per cmake
    FIND_PATH(CATCH_INCLUDE_DIR
        catch.hpp
    )
ENDIF()


My Ubuntu installation includes a catch.hpp under /usr/include. This is because
I have the catch package already installed:

apt-get install catch

My source directory includes a contrib/catch/catch.hpp file.

Adding a MESSAGE("Found Path? ")(${CATCH_INCLUDE_DIR}) before the IF() shows us
that the CATCH_INCLUDE_DIR is already set and it is "/usr/include" instead of
the expected "${CMAKE_SOURCE_DIR}/contrib/catch".



Additional Information: 
There is a work around, which makes me think that the problem is that PATHS (and
probably HINTS) does not properly recognize NO_DEFAULT_PATH as a flag and no see
it as a path...

All I have to do is to put the NO_DEFAULT_PATH ahead of the PATHS specification.

FIND_PATH(CATCH_INCLUDE_DIR
    catch.hpp
    NO_DEFAULT_PATH
    PATHS
        ${CMAKE_SOURCE_DIR}/contrib/catch 
        ${CMAKE_SOURCE_DIR}/contrib
)

See also my Stackoverflow.com entry here:

http://stackoverflow.com/questions/37534142/how-do-i-get-cmake-to-choose-the-header-found-in-my-contrib-directory/37534160#37534160
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Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2016-05-31 20:27 Alexis Wilke   New Issue                                    
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