[PATCH] Postpone __LINE__ evaluation to the end of #line directives

[Joseph S. Myers]

On Wed, 27 Nov 2013, mtewoodbury@gmail.com wrote:

> Copyright 2013 assigned to the Free Software Foundation.

FWIW I don't see this in copyright.list yet.  If you sent the paperwork 
(whether paper mail or scans) to the FSF over a week ago and haven't had 
it acknowledged, please chase up assign@gnu.org, and keep chasing them up 
weekly until it's acknowledged and a maintainer confirms it's now listed 
in copyright.list.

> diff --git a/gcc/testsuite/gcc.dg/cpp/line4.c b/gcc/testsuite/gcc.dg/cpp/line4.c

I think it's best to leave this test as-is and add a new test line9.c 
specifically for this case of "#line __LINE__".  Changing existing tests 
unnecessarily complicates establishing whether a newly seen failure is a 
regression or not.

I think it would be worth including tests where the __LINE__ expansion 
(which as you note should be the line number of the line *after* the 
directive) is involved in concatenation or stringized, e.g.

#define xstr(x) #x
#define str(x) xstr(x)
#line 1 str(__LINE__)

which should set __FILE__ to be the stringized number of the line after 
the directive.  (I hope these cases will just work given your patch, so 
this is just a matter of adding more to the testcase.)

-- 
Joseph S. Myers
joseph@codesourcery.com