NetNews Usenet Archive 1992 #18/NN_1992_18.iso/spool/comp/lang/c/12334

Internet Message Format | 1992-08-14 | 1.9 KB

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From: [e-mail] (Tom Wright)
Newsgroups: comp.lang.c
Subject: need tool to eliminate unused #include's
Message-ID: <[e-mail]>
Date: 14 Aug 92 17:09:26 GMT
Sender: [e-mail] (Tom Wright)
Organization: Megatek Corporation, San Diego, California
Lines: 30

Over time, programmers tend to add #include's but never remove them,
regardless of if they're still needed. It's just too difficult to see
if they're still needed. Ultimately, in a large system, this causes
'make' or 'Imake' to do many needless recompiles if dependencies are
used. Not using dependencies causes many wasted hours of looking for
bugs that aren't really there.

Does anyone know of a tool that figures out if any of the #include's
in a module are no longer needed?

It has been suggested that one could selectively remove #include's and
try recompiling and looking for no errors, but this is unsatisfactory
in that the use of -D on the compile command line could make an #include
that had appeared unneeded in a previous compile now become needed.

I imagine the tool would have to build a list of each thing that I'll
call a symbol that is defined in a #define, a typedef, or a struct (or
a few other things I haven't thought of yet) and which .h it's defined
in (ignoring #ifdef's and #ifndef's). Then it would have to keep track
of which .h's they're used in and which symbols they're used in. Ultimately,
it would check the module source to see what gets used. To create the
final answer, it would need to check all the symbols in each .h to see
if any of them were ultimately used in the source or in a .h that had
a symbol that got used.

Creating such a processor would be non-trivial, but the productivity
gain could be very large. Does anyone have such a thing?

Thanks,
Tom