[cfe-dev] -fdiagnostics-format= I have a quesiton about -fshow-column

[Douglas Gregor]

On May 20, 2011, at 9:25 AM, Andrew Fish wrote:

> I updated the -fdiagnostics-format implementation based on the feedback, and added a test case. When adding support for columns for msvc I ran into the issue that -fshow-column was not supported, as implied by the documentation, so I had to also fix that in the patch. I added -fshow-column to the test case, since it was obviously missing.
> 
> The default behavior for -fms-extensions folks is the same as before.
> 
> -fdiagnostics-format=clang/msvc/vi: Changes diagnostic output format to better match IDEs and command line tools.
> This option controls the output format of the filename, line number, and column printed in diagnostic messages. The default for this option is clang. If ifms-extensions is set then the default is changed to msvc and -fno-show-column is also set.
> For example, a format string warning will produce these three renditions based on the setting of this option, the fourth rendition shows default output when -fms-extensions is set:
> 
>   t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int'
>   t.c(3,11) : warning: conversion specifies type 'char *' but the argument has type 'int'  
>   t.c +3:11: warning: conversion specifies type 'char *' but the argument has type 'int' 
>   t.c(3) : warning: conversion specifies type 'char *' but the argument has type 'int'  
> 
> 
> In this code from ParseDiagnosticArgs():
> 
>     if (Args.hasArg(OPT_fms_extensions)) {
>       Opts.Format = DiagnosticOptions::Msvc;
>       Opts.ShowColumn = Args.hasArg(OPT_fshow_column);
>     } else 
>       Opts.Format = DiagnosticOptions::Clang;
> 
> The call to Args.hasArg(OPT_fshow_column) always seems to return 0? Does this mean I did not add -fshow-column correctly?

hasFlag() is far better than hasArg() for what you're doing, since it handles both the positive (-fshow-column) and negative (-fno-show-column) arguments in one command. For example, I switched the ShowColumn computation to this:

  Opts.ShowColumn = Args.hasFlag(OPT_fshow_column,
                                 OPT_fno_show_column,
                                 /*Default=*/true);

I committed a slightly-tweaked version of your patch as Clang r131794, where I also got rid of the dependence on -fms-extensions. Thanks so much for working on this!

	- Doug
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