-E from stdin loses standard include paths?

[Phil Edwards]

Forgive me if this is normal behavior, but I just ran into something strange.

This works:

    fenric 69% echo '#include <string>' > p.cc
    fenric 70% g++ -E p.cc
    [many lines of code on stdout, all good]

This doesn't:

    fenric 71% echo '#include <string>' | g++ -E -
    # 1 "<stdin>"
    # 1 "<built-in>"
    # 1 "<command line>"
    # 1 "<stdin>"
    <stdin>:1:18: string: No such file or directory
    fenric 72%

This strikes me as non-intuitive.


-- 
I would therefore like to posit that computing's central challenge, viz. "How
not to make a mess of it," has /not/ been met.
                                                 - Edsger Dijkstra, 1930-2002