[LLVMdev] [PATCH] A "very verbose" mode for FileCheck

[Dmitri Gribenko]

On Wed, Jan 16, 2013 at 9:24 PM, Chris Lattner <clattner at apple.com> wrote:
>
> On Jan 16, 2013, at 10:32 AM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
>
>> Hello,
>>
>> When someone breaks a FileCheck-based test on some buildbot, sometimes
>> it may not be obvious *why* did it fail.  If the failure can not be
>> reproduced locally, it can be very hard to fix.
>>
>> I propose adding a "very verbose" mode to FileCheck.  In this mode
>> FileCheck will dump the input file in case of failure.  This mode will
>> be enabled by an environment variable "FILECHECK_VERY_VERBOSE".  If we
>> chose a command line option, we would have to edit all FileCheck-based
>> tests to use %FileCheck.
>
> I think that this idea is good, but I'd prefer it be implemented a different way:
>
>  - Filecheck should take a new flag -dump-input-on-error that causes it to... dump the input file on error.
>  - Lit should be the thing that checks the environment (or perhaps add a new option to lit), and adds the flag to FileCheck invocations.
>
> I don't like it when the behavior of such a low-level tool like this changes based on environment variables.  It isn't discoverable in --help.  If for some reason, it is bad for lit to implicitly pass the option, I'd rather have a standard FILECHECK_COMMANDLINE environment variable, and have filecheck parse arbitrary options out of it using the cl::ParseEnvironmentOptions function.

I agree that a command line option would be better.  But in that case
all tests should be updated.  It is not an issue for me -- it is
mostly mechanical.  So should I change tests to use %FileCheck?

Dmitri

-- 
main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
(j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/