[ET Trac] [Einstein Toolkit] #1522: Improve determining make dependencies

[Einstein Toolkit]

#1522: Improve determining make dependencies
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  Reporter:  eschnett     |       Owner:                     
      Type:  enhancement  |      Status:  new                
  Priority:  major        |   Milestone:                     
 Component:  Cactus       |     Version:  development version
Resolution:               |    Keywords:                     
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Comment (by eschnett):

 This simple line does not work if one of the dependencies vanishes.
 Currently, if you have a header file in a thorn, and then remove the
 header file because you don't need it any more, the respective *.d file
 still records the dependency. Cactus will then abort with an error stating
 that it does not know how to generate this header file. A make *-cleandeps
 is required. This is annoying.

 The magic above -- listing the header file without dependencies -- teaches
 make that this is fine, i.e. that the header file does not need to be
 generated. The respective source file will be recompiled (which needs to
 happen), and the correct dependencies be generated.

 This is actually a long-standing and deep problem with Makefiles. I'm sure
 there is a discussion on the web regarding this, but I unfortunately don't
 have a pointer.

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/1522#comment:9>
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