temp preprocessed filename

[Michael Morrell]

Here's a smaller testcase:

  typedef int ptrdiff_t;

  namespace std {
    using ::ptrdiff_t;
  }

  void foo() {}

when you run:

  g++ -g -E foo.cpp > foo.ii; g++ -g -c foo.ii

the foo.o produced contains a reference to foo.ii in .debug_line.

  Michael