[cfe-commits] [PATCH] Correct first-line indentation in preprocessor output

[Hal Finkel]

----- Original Message -----
> From: "Eli Friedman" <eli.friedman at gmail.com>
> To: "Hal Finkel" <hfinkel at anl.gov>
> Cc: "llvm cfe" <cfe-commits at cs.uiuc.edu>
> Sent: Wednesday, January 9, 2013 4:40:18 PM
> Subject: Re: [cfe-commits] [PATCH] Correct first-line indentation in preprocessor output
> 
> On Wed, Jan 9, 2013 at 2:20 PM, Hal Finkel <hfinkel at anl.gov> wrote:
> > Currently, the -E output from clang does not produce the correct
> > indentation on the first line. This is because MoveToLine returns
> > false, and when this happens, the regular process for producing
> > initial indentation is skipped. This patch makes sure this does
> > not happen on the first line -- it is not clear to me whether
> > there are other circumstances where the current logic could be
> > problematic.
> >
> > It looks like calling SourceManager::getPresumedLoc is a relatively
> > expensive operation, so however this is fixed, I assume that we
> > want to minimize calls to that function.
> >
> > Please review.
> 
> --- a/lib/Frontend/PrintPreprocessedOutput.cpp
> +++ b/lib/Frontend/PrintPreprocessedOutput.cpp
> @@ -139,10 +139,13 @@ public:
>                                  diag::Mapping Map, StringRef Str);
> 
>    bool HandleFirstTokOnLine(Token &Tok);
> -  bool MoveToLine(SourceLocation Loc) {
> +  bool MoveToLine(SourceLocation Loc, bool *FirstLine = 0) {
>      PresumedLoc PLoc = SM.getPresumedLoc(Loc);
> -    if (PLoc.isInvalid())
> +    if (PLoc.isInvalid()) {
> +      if (FirstLine) *FirstLine = false;
>        return false;
> +    }
> +    if (FirstLine) *FirstLine = PLoc.getLine() == 1;
>      return MoveToLine(PLoc.getLine());
>    }
>    bool MoveToLine(unsigned LineNo);
> 
> There is precisely one user of the return value of MoveToLine: the
> one
> you're modifying.  Why do we need an extra out parameter?

Good point, thanks! Revised patch attached -- which now changes one source line ;)

 -Hal

> 
> -Eli
> 

-- 
Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory
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