cpplib: Use translation unit line numbers

[Neil Booth]

Gabriel Dos_Reis wrote:-

> 100% agreed.  I hope to eventually replace those with the 
> non-_with_file_and_line versions.  It seems like your patch will make
> my life eaiser.  Thanks :-)

What do you think we should do with macros for diagnostics?  Each
token now contains the line it was *lexed* on.  So, for example, in

#define foo bar
foo

The token "bar" received by the front ends will contain the line and
column it appeared in the #define line.  Some people claim they would
like diagnostics to be pointed within the macros like this.

However, like #include stack, we should have the source line that the
problem actually occurred on.  e.g.

in file included from file:line:col
in macro MACRO expanded from file:line:col
file:line:col:<message>

There are as many as 3 lines associated with any given token: the line
it is originally lexed on, the line the token is output on in
preprocessed output (different for e.g. escaped newlines and funlike
macro arguments).  If a token comes from a macro expansion, you also
have the line of the macro invocation (which is where diagnostics
currently point).

Juggling these, along with a few lexical and grammatical oddities,
makes this part of cpplib quite a nightmare.

Neil.