[cmake-developers] [CMake 0014701]: check_include_file never re-runs because it use the variable as cache

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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http://public.kitware.com/Bug/view.php?id=14701 
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Reported By:                Andreas Pakulat
Assigned To:                
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Project:                    CMake
Issue ID:                   14701
Category:                   CMake
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
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Date Submitted:             2014-01-15 05:17 EST
Last Modified:              2014-01-15 05:17 EST
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Summary:                    check_include_file never re-runs because it use the
variable as cache
Description: 
When using check_include_file to verify a certain header can be used, the result
of the try_compile is cached by check_include_file using the same variable that
is passed in to check_include_file. This means a second run of cmake will not
run the try-compile again because the variable is already defined and hence the
check at the top of check_include_file goes into the else branch.

This breaks the common idiom of running cmake for a project to find out which
dependencies might be missing, then installing needed dependencies and simply
re-run cmake (without deleting the build directory). In addition this is rather
hard to debug for someone that just uses a project and is not overly familiar
with CMake.
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Issue History 
Date Modified    Username       Field                    Change               
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2014-01-15 05:17 Andreas PakulatNew Issue                                    
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