Re: CPP indentation bikeshed (was: Emacs master build failing on RHEL 6.8)

[Paul Eggert]

Stefan Monnier wrote:
> CPP doesn't know anything about C's
> syntactic structure (such as {...} nesting)

That's going a bit too far, as cpp does knows about C's comments and about C's 
parentheses and commas. True, cpp pays no special attention to { and }.

My own feeling is that in cases like these, utility trumps philosophical 
consistency. When an '#if' is required but otherwise has the function of a plain 
'if', the code is clearer when indented consistently with plain 'if' as this 
gives the reader a simple and helpful visual cue: an indented "#" means that the 
preprocessor code is following the normal C syntactic structure, whereas an 
unindented "#" means the preprocessor code is unusual and is breaking the normal 
C structure. Always shoving the "#" to the left loses this useful information 
and forces the reader to work harder.