>>...The reason for my question is that reacently I've try to build some application and It did not compiled without command-line
>>options, but did compile (and link) when I used some of these switches.

A GCC compiler always requires a set of some options. I also checked my docs for these switches:

-gcc-name
-gcc-version
-gxx-name
-cxxlib=dir
-cxxlib-nostd
-no-cxxlib

and I haven't found anything (!). Did you read descriptions for these switches on some web site?

icc and icpc are only compilers.They use the GNU tools on the system. So for example, they use the GNU header files like stdio.h and GNU linker and libraries. For these reasons the compiler has to be compatible with GNU -- for example if you have GNU version 4.6 on your system, icc/icpc tries to act just like GNU 4.6 (with the same features and bugs). 

So the compiler will try to figure out which version of GNU you have installed by looking at the gcc or g++ in your PATH. You can override this behaviour by using some of the -gcc switches above.

The cxxlib switches have to do with linking in the GNU C++ library libcxx.

Please read the documentation and if you have a specific question please ask. Do an icpc -help for documentation. 

Judy

In an upcoming release of the compiler, we expect that the -gcc-version option is going to be deprecated, and we'll recommend that it not be used.  There are 2 ways to select your desired version of gcc, one is through establishing your environment (path variable) and the other is by using the option -gcc-name.  Can you give more background about what you're trying to find out?

ok let me try to start to answer your questions...

The -gcc-version flag can effect the compilation in hundreds of ways. For example, if you specify -gcc-version=340 the compiler will try to act just like GNU version 3.4. If you specify -gcc-version=460 the compiler will try to act like GNU version 4.6. This can effect name lookup, function matching, which C99 or c++11 features or GNU features are enabled, to name just a few of the hundreds of differences. So it's not suprising to hear the a program can be successfully compiled or not depending on the value of the switch. -gcc-version only effects the behavior of the compiler itself, it does not effect what GNU headers or libraries are used. It affects both C and C++ so there is no need for a different switch called -gxx-version.

The gcc-name will tell the compiler which gcc to use (instead of the one found in your PATH) and then the compiler will figure out from that which version of gcc is being used (by doing a gcc -v) and implicitly set the right gcc-version for the compiler. In particular the C++ standard library files that are shipped with say GNU version 4.6, are unlikely to compile if you specify -gcc-version=340. So you either shouldn't specify -gcc-version or you should make sure that the -gcc-version you specify matches the version of the GNU header files and libraries that you are using.

None of these switches are necessary -- as I said the default behaviour of icc or icpc is to look at the first gcc or g++ it finds in your PATH. Then it will figure out which gcc version and set it automatically. If you set both -gcc-name and -gcc-version then you are probably doing something wrong, since the compiler will figure out -gcc-version by looking at the gcc that you've pointed at. Note that -gcc-name and -gxx-name will not only implicitly set -gcc-version for the compiler but will also affect where the GNU headers and GNU libraries are used.

The reason -cxxlib requires a directory argument is it indicates where all the GNU headers, binaries, and libraries are going to be used. i.e. there are multiple libraries libcxxstdc++, libmudflap, libomp, etc. For example let's says you had a GNU 4.5 distribution that was located here:

sptxl8-123> ls /rdrive/ref/gcc/4.5.0/rhel50/x86
bin  include  lib  libexec  share
sptxl8-124> icpc -cxxlib=/rdrive/ref/gcc/4.5.0/rhel50/x86 x.cpp

The switch will cause the compiler use the include files from include and use the libraries from lib in //. The compiler should also set -gcc-version to 450 automatically. You could do the same thing by specifying -gxx-name=/rdrive/ref/4.5.0/rhel50/x86/bin/icpc.

-cxxlib-nostd only effects the C++ standard library. It tells the compiler to not search the C++ system include directories so for exampe #include <iostream> will not compile but #include <stdio.h> will. It also prevents linking of  libcxxstd since the driver leaves off the -lcxxstd option.

-no-cxxlib is more general, it will also affect the linking of all C++ runtime libraries, not just libcxxstd. So a program that only uses printf, for example, will not link with -no-cxxlib option but will link with the -cxxlib-nostd option.

Not sure why there is nothing equivalent for the standard C library, my guess is noone has ever asked for such a thing.

If you set both gcc-name and gxx-name then gcc-name will be used whey you say "icc" and gxx-name will be used when you say "icpc".

I'm sure I haven't answered all your questions but I hope this is a start. If you want to experiment with these options yourself to see what the driver is doing you can add the -dryrun option and the compiler will show you the compile and link commands it would use if it was doing an actual compilation.

Judy

Just as a comment, libc isn't supplied as part of gcc.   On linux, it's a version of glibc, typically a fixed version for a given distribution, and gcc can be upgraded without changing gblic.  It's typically necessary to build on a platform which has the oldest libc version installed which you want to support, as binaries built for a given glibc are compatible at least with the following major version.

There is a libgcc2 which comes with gcc, generally containing functions such as double to unsigned int casts, but I haven't a case where it is a critical choice for icc.

libstdc++ does have to be kept consistent with the g++ version in use.  In the past, there were more versions of Intel C++ which gave you a choice between their own Dinkumware STL and libstdc++ than there are now, so the libstdc++ found on the current g++ path is the default on the usual platforms where g++ is available.

Yes I think your summary is correct. The -gcc-name option is also useful if for some reason you need to use different versions of GNU on one system. We have actually deprecated the -gcc-version option in our development compiler since it seems to just cause problems with users who use it incorrectly (and wonder why they are having problem compiling the GNU headers).

I submitted your documentation request in our bug tracking system as tDPD200240972. I was actually thinking the same thing as I started answering your questions...

thanks, Judy