Re: what's the proper include search path for the cross-gcc?

[Jim Tison <jtison at ntplx dot net>]

And another trick I've leaned on more than once:

   export C_INCLUDE_PATH=dir1:dir2:dir3...:dirN
   export CPLUS_INCLUDE_PATH=dir1:dir2:...:dirN
   ${target}-gcc
You can use either/both of these in conjunction with -nostdinc to 
**completely** change the default search path to one of your absolute 
liking, too. Not being a Fortran/ObjC/Ada/Java kind of guy, I don't know 
if there are comparable variables that support these languages.

You'll see the sysroot being searched as part of the default path if you 
built --with-sysroot.

It pays to read info {gcc,gccint} carefully; but I'm always willing to 
regress to child state to learn ... just ask my wife :-)

Peace,
--Jim--

Kai Ruottu wrote:

> Robert P. J. Day wrote:
>
> >   i'm sure i'm about to embarrass myself here but what is the
> > appropriate include directory search path for the generated cross
> > compiler?
>
>
> The 'rocket science' comes here :
>
> Headers will be used by the "C Pre Processor", 'cpp', so the only one
> which could tell where it searches those headers could be the 'cpp'.
> The other GCC binaries maybe don't care where the headers are.
>
> >   and how can i print out where a header file would be found?  i tried
> > the "-print-search-dirs"
>
>
>  With 'cpp' ?  With 'gcc' ?  With 'cc1' ? With 'cc1plus' ?
>
> > but, while that prints the search sequence
> > for shared libs, it doesn't say anything about how a given header file
> > would be located.
>
>
> One should be like a child with these things :-) Trying everything and
> seeing what happens, can sometimes teach a lot. For instance one has
> learned the '-v' option with 'gcc' and wants to see what it gives with
> the other GCC binaries. It can for instance give the following :
>
> F:\usr\local\lib\gcc-lib\sh-linux-gnu\3.0>cpp0 -v
> GNU CPP version 3.0 20010416 (prerelease) (cpplib) (SH GNU/Linux with 
> ELF)
> #include "..." search starts here:
> #include <...> search starts here:
>  /usr/local/include
>  /usr/local/lib/gcc-lib/sh-linux-gnu/3.0/include
>  /usr/local/sh-linux-gnu/sys-include
>  /usr/local/sh-linux-gnu/include
> End of search list.
> cpp0:  is a block device
>
> F:\usr\local\lib\gcc-lib\sh-linux-gnu\3.0>cc1 -v
> GNU CPP version 3.0 20010416 (prerelease) (cpplib) (SH GNU/Linux with 
> ELF)
>         .file   "stdin"
> #include "..." search starts here:
> #include <...> search starts here:
>  /usr/local/include
>  /usr/local/lib/gcc-lib/sh-linux-gnu/3.0/include
>  /usr/local/sh-linux-gnu/sys-include
>  /usr/local/sh-linux-gnu/include
> End of search list.
> cc1:  is a block device
>         .ident  "GCC: (GNU) 3.0 20010416 (prerelease)"
>
> Execution times (seconds)
>  preprocessing         :   0.00 ( 0%) usr
>  lexical analysis      :   0.00 ( 0%) usr
>  parser                :   0.09 (53%) usr
>  varconst              :   0.00 ( 0%) usr
>  symout                :   0.00 ( 0%) usr
>  TOTAL                 :   0.17
>
> BTW, the last rows were interesting... Maybe some day someone asks how
> one can see how long times the 'compiler' will spend in its 'compile
> phases' !
>
> As seen, the '-v' doesn't say much about the C++ headers... Hmmm, what
> else nice options there could be. Needing help... Is there an option
> giving help? What if one writes 'help' as the option? GNU tools require
> two dashes with a 'long' option, so the option could be '--help' or how?
>
> Trying the '--help' with the 'cpp0' gives some interesting options :
>
>   -lang-c                   Assume that the input sources are in C
>   -lang-c89                 Assume that the input sources are in C89
>   -lang-c++                 Assume that the input sources are in C++
>   -lang-objc                Assume that the input sources are in 
> ObjectiveC
>   -lang-objc++              Assume that the input sources are in 
> ObjectiveC++
>   -lang-asm                 Assume that the input sources are in 
> assembler
>
> What if one tries the '-v' and the '-lang-c++' together :
>
> F:\usr\local\lib\gcc-lib\sh-linux-gnu\3.0>cpp0 -v -lang-c++
> GNU CPP version 3.0 20010416 (prerelease) (cpplib) (SH GNU/Linux with 
> ELF)
> ignoring nonexistent directory "/usr/local/include/g++-v3/sh-linux-gnu"
> #include "..." search starts here:
> #include <...> search starts here:
>  /usr/local/include/g++-v3
>  /usr/local/include
>  /usr/local/lib/gcc-lib/sh-linux-gnu/3.0/include
>  /usr/local/sh-linux-gnu/sys-include
>  /usr/local/sh-linux-gnu/include
> End of search list.
> cpp0:  is a block device
>
> Hey, now it showed some C++ header paths !
>
> >   i'm sure this is trivial stuff, i'm just realizing that maybe i
> > don't understand it as well as i should.
>
>
> Please become a child again and start to toy with the world :-)
>
> Ok, jokes enough... Seeing the headers search paths seems to not be
> standardized in any way, so if one has learned to use the :
>
>   cpp -Wp,-lang-c++,-v
>
> like :
>
> F:\usr\local\bin>cpp-sh-linux-b -Wp,-lang-c++,-v
> GNU CPP version 3.0 20010416 (prerelease) (cpplib) (SH GNU/Linux with 
> ELF)
> ignoring nonexistent directory "f:/usr/local/include/g++-v3/sh-linux-gnu"
> ignoring nonexistent directory "/usr/local/include/g++-v3/sh-linux-gnu"
> #include "..." search starts here:
> #include <...> search starts here:
>  f:/usr/local/include/g++-v3
>  f:/usr/local/lib/gcc-lib/sh-linux-gnu/3.0/include
>  f:/usr/local/sh-linux-gnu/sys-include
>  f:/usr/local/sh-linux-gnu/include
>  /usr/local/include/g++-v3
>  /usr/local/include
>  /usr/local/lib/gcc-lib/sh-linux-gnu/3.0/include
>  /usr/local/sh-linux-gnu/sys-include
>  /usr/local/sh-linux-gnu/include
> End of search list.
> cpp0.exe:  is a block device
>
> this maybe doesn't work any more with the next GCC release :-(
>
> Generally I don't know where people will need the '$target-cpp' which
> will be installed always, into the same place with the '$target-gcc',
> '$target-g++' etc.  But now we know at least one use for that: to try
> to see the headers search paths...
>
> The output with the '-print-search-dirs' can be really surprising :
>
> F:\usr\local\bin>cpp-sh-linux-b -print-search-dirs
> install: /usr/local/lib/gcc-lib/sh-linux-gnu\3.0\
> programs: =f:\usr\local\lib\gcc-lib\sh-linux-gnu\3.0\;
>
> and so on, nothing about those headers!
>
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