[ET Trac] [Einstein Toolkit] #1345: Cactus shouldn't mess with some flags after they have been setup.

[Einstein Toolkit]

#1345: Cactus shouldn't mess with some flags after they have been setup.
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 Reporter:  knarf   |       Owner:                     
     Type:  defect  |      Status:  new                
 Priority:  major   |   Milestone:  ET_2013_11         
Component:  Other   |     Version:  development version
 Keywords:          |  
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 Currently Cactus sets up flags like CPPFLAGS or CFLAGS by adding e.g.
 CPP_OPENMP_FLAGS. However, later it overwrites these again by their
 original value in sbin/ProcessConfiguration.pl (search for FIXME).

 The attached patch implements what the 'FIXME' suggests - accepting the
 drawbacks that are mentioned there: that configuration settings not
 originating from a thorn might not be forwarded from e.g., a
 .cactus/config file. MPI was one of these, but this is now handled
 differently anyway. With this patch, we would need to be aware of these
 and might need to add them to @allowed_opts in the future.

 Without the patch however, compilation might fail for perfectly valid
 setups. One of these is when using openmp, setting all the corresponding
 *_OPENMP_FLAGS, but not setting CPPFLAGS (only CPP_OPENMP_FLAGS). In this
 case ProcessConfiguration.pl will set CFLAGS to the version in the config
 file (*without* the -openmp), but it will leave CPPFLAGS to the version
 *with* -openmp. This later leads to a linker error in external libraries,
 since compilation there uses CPPFLAGS (with openmp), but the linker
 doesn't (It correctly uses CFLAGS, but this doesn't have openmp flags
 here).

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1345>
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