Re: compile errors from gcc

[Kai Ruottu <karuottu at mbnet dot fi>]

D Macean wrote:
> It has always been a mystery to me where the header files come from
Maybe this is a mystery for many GCC users, at least "how to get GCC to tell
where it will search the headers as default" is a question which is hard 
to answer....

The somehow-known "-print-search-dirs" GCC option only shows the "programs"
(cc1*, collect2, as, ld etc) and libraries search paths,  but the clue 
here is "which
component of GCC would need the headers?"   Of course it is the "C 
preprocessor"
aka "cpp", not "gcc" or "g++" in C++ case.  So one should experiment 
with the 'cpp'
command !  The obvious 'cpp -print-search-dirs' however is a 
disappointment but
the quite common '-v' should give a better result, but stopping during 
its run and then
waiting some input from the keyboard (stdin) :-(   A Ctrl-C helps...

Nowadays the "real cpp" is moved into those 'cc1' and 'cc1plus' programs 
and if
one tries them directly, also they should tell those headers search 
paths with the
'-v' option... And will stop in their output.

When only that 'cpp' is available, it could be expected that there is 
some "standard"
way to see the headers search paths with it...  But surprisingly there 
isn't :-(

In old GCCs giving commands to the preprocessor via the '-Wp,<command>' was
the way and a :

 gcc -Wp,-v

worked with C and a :

 gcc -Wp,-v,-lang-c++

worked with C++ --  to give those headers search paths without really 
"compiling"
anything... Nowadays when knowing that 'cc1plus' will also be the 
"preprocessor"
with C++, one can try something like :

  `gcc -print-prog-name=cc1plus` -v

in order to get the 'cc1plus' associated with the 'gcc' (whereever it 
then is) to be run
with that needed '-v' option and then it telling the C++ and C headers 
search paths...

Complicated, could someone say :-(  These things could really be easier...

Of course during a real compile with 'gcc' or 'g++' using a '-v' will 
give its verbose
output, including the headers search paths but something similar with the :

  gcc -print-search-dirs

option could be expected also for the headers and the :

 cpp -print-search-dirs

could be the chosen command for the headers....