What is the purpose of 'warning: no newline at end of file'?

[Jonathan Turkanis]

[Sorry Neo, I think I sent you personal email accidentally]

Neo Anderson wrote:

 > So, what is the purpose of this warning? What possible 'damages' does this 
warning protect against?


I believe this language was added to the standard because at the time some 
systems were not able to handle files properly if they didn't end in a newline. 
This wording made it possible to provide conforming C++ implementations for 
those platforms.

I'm not sure if there still are any such systems, but because the standard has 
given implementations to freedom to do whatever they want (that's what undefined 
behavior means) if you tell them to process a file not ending in a newline, be 
warned that if you try to compile your code on another system, the compiler may 
refuse. I know, for example, that Comeau in strict mode won't compile it. For 
that matter, neither will gcc with -pedantic-errors.

Jonathan

 > And, what is the 'the behavior'?
 >
 > ----Original Message Follows----
 > From: Jonathan Turkanis <technews@kangaroologic.com>
 > To: gcc-help@gcc.gnu.org
 > Subject: Re: What is the purpose of 'warning: no newline at end of file'?
 > Date: Wed, 06 Jul 2005 21:41:20 -0600
 >
 > Neo Anderson wrote:
 >
 >> I don't even think it's a problem. Why do I need (or better have) a line ending?
 >
 >
 >
 > The C++ standard says: If a source file that is not empty does not end in a 
newline character, or ends in a newline character immediately preceded by a 
backslash character, the behavior is undefined. (2.1/1)
 >
 > Jonathan
 >
 >
 >
 >