test failure in SourceManager::getLineNumber()

If I build with ENABLE_EXPENSIVE_CHECKS=1, I get this failure in
Preprocessor/header_lookup1.c. The "are not partitioned" error comes
from the fact that __last is actually pointing not to *just* past the
end of the sorted values, but to one element further on than that.

The attached patch fixes it for me, and I think it's correct, but
there are a lot of ad hoc "+1" and "-1"s in that function that make me
feel a bit uncomfortable (in particular maybe this one could do with a
comment:

  unsigned QueriedFilePos = FilePos+1;

)

Thanks,
Jay.

/usr/include/c++/4.3/bits/stl_algo.h:2082:error: elements in iterator range
    [__first, __last) are not partitioned by the value __val.

Objects involved in the operation:
iterator "__first" @ 0x0xbf859830 {
type = Pj;
}
iterator "__last" @ 0x0xbf859834 {
type = Pj;
}
0 clang-cc 0x091e2c4f
1 clang-cc 0x091e32ee
2 0x4001c400 __kernel_sigreturn + 0
3 libc.so.6 0x4019d018 abort + 392
4 libstdc++.so.6 0x4009f531
__gnu_debug::_Error_formatter::_M_error() const + 529
5 clang-cc 0x0827f584
6 clang-cc 0x085637db
7 clang-cc 0x085638f3
8 clang-cc 0x080d73d9
9 clang-cc 0x080d76af
10 clang-cc 0x080d77bc
11 clang-cc 0x080d7ef7
12 clang-cc 0x0811514c
13 clang-cc 0x081166ec main + 2626
14 libc.so.6 0x40186455 __libc_start_main + 229
15 clang-cc 0x08096561
Stack dump:
0. Program arguments:
/home/foad/llvm/objdir-svn/Debug+Checks/bin/clang-cc -I /usr/include
/home/foad/svn/llvm-project/cfe/trunk/test/Preprocessor/header_lookup1.c
-E

patch.sourcemanager (395 Bytes)

Hi Jay,

I haven't been able to convince myself that the patch is correct (in
the 5 minutes I've taken to stare at the code). LastLineNoResult
should be a valid line number, which I would presume to be a valid
offset into Content->SourceLineCache, so the +1 seems reasonable to
me.

I'd like to chat with Chris about this code but he is gallivanting
about on vacation, so I applied what is I believe an obviously correct
patch which should fix your problem, and added some FIXMEs to the
code, here: http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20090518/017397.html

- Daniel