I tried compiling a test file with the -v -H flags.
This is what I got:

E:\temp>g++ -v -H main.cpp
Using built-in specs.
Target: mingw32
Configured with: ../gcc-4.1.1 /configure --with-gcc --with-gnu-ld --with-gnu-as --host=mingw32 --target=mingw32
--prefix=/mingw --enable-threads --disable-nls --enable-languages=c,c++ --disable-win32-registry --disable-sh
ared --without-x
Thread model: win32
gcc version 4.1.1
c:/mingw/bin/../libexec/gcc/mingw32/4.1.1/cc1plus.exe -quiet -v -iprefix c:\mingw\bin\../lib/gcc/mingw32/4.1.
1/ -H main.cpp -quiet -dumpbase main.cpp -auxbase main -version -o C:\DOCUME~1\Do\LOCALS~1\Temp/ccqWaaaa.s
ignoring nonexistent directory "/mingw/include"
ignoring nonexistent directory "C:/MinGW/mingw32/include"
ignoring nonexistent directory "/mingw/include"
#include "..." search starts here:
#include <...> search starts here:
c:/mingw/bin/../lib/gcc/mingw32/4.1.1/include
C:/MinGW/include/c++/4.1.1
C:/MinGW/include/c++/4.1.1/mingw32
C:/MinGW/include/c++/4.1.1/backward
C:/MinGW/include
C:/MinGW/lib/gcc/mingw32/4.1.1/include
End of search list.

As you can see it does search first gcc system float.h. I have a few questions regarding that.
how do I change the order of files to search?
why doesn't gcc recognize the relative search path "/mingw/include",
and why is it included twice?
 
dave

On 10/17/06, Danny Smith < dannysmith@clear.net.nz> wrote:

>
> I suspect that include path is picking up the gcc system float.h before
> the /mingw/include/float.h.
>
> What does adding -v to compile flags tell you?
> What does adding -H to compile flags tell you?
>
> Danny
>
>