Re: Target C++ header file location rationale?

[Jonathan Larmour <jifl at eCosCentric dot com>]

Jonathan Larmour wrote:
> Hi all,
>
> Since the list archive is still off-line ( "Unable to read word database 
> file '/sourceware/htdig/gcc/db/db.words.db'" ) I may as well ask direct...
>
> In a cross-compilation build with 3.2.1, target headers get installed in 
> $(prefix)/include with target-specific additions going under the bits/ 
> subdir therein. What is the rationale for them living here for cross 
> builds?
>
> By installing in $(prefix)/include they get mixed up with a bunch of 
> host header files in a complete toolchain like, say, tcl.h (if you were 
> configuring a full toolchain that included gdb and insight, say). This 
> can cause confusion since that is associated with the host, and there is 
> no tcl port for the target.
>
> Less relevant to me but significant is that the same applies in reverse 
> - if you wanted to include that directory on the host, header files only 
> really appropriate for the target could be pulled in. This could be 
> relevant if this directory was ahead of others on the include path.
>
> As you know, they used to be installed in $(prefix)/$(target)/include, 
> and that still makes sense.
This is, of course, completely b*llocks. I was misremembering. It's always 
been like this, even for libstdc++-v2. I'd still appreciate an answer if 
possible? Particularly to the question below if nothing else.

Thanks,

Jifl



> What if we configure with 
> --with-gxx-include-dir=$(prefix)/$(target)/include, is there any 
> potential for things to go wrong now, or in the future? Is that 
> something we can use without fear?
>
> Now while in general I think it's better to go with whatever the 
> defaults are, it's difficult to see why in this case, especially when 
> there are disadvantages.
>
> Ta for any insights,
>
> Jifl

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