[cfe-dev] Creating 'clang-mutate' for clang-tools-extra

[Piotr Padlewski via cfe-dev]

That is interesting idea. The other mistake that would be easy to change is
finding +1 errors like

for (int i = 0 ; i < n ; i++ )
=>
for (int i = 0 ; i <= n ; i++)

or changing ++it to it++ in the cases where the result goes to other expr.

Piotr

2016-08-09 8:47 GMT-07:00 David Blaikie via cfe-dev <cfe-dev at lists.llvm.org>
:

> Haven't heard of anyone working on it (& don't have time myself) - but
> I've been looking forward to/wanting to see such a tool in LLVM/Clang for a
> while now. (if you could have it running on a buildbot or similar that
> tracked LLVM changes so we could vet code change test coverage... that'd be
> so awesome)
>
> I'd always pictured such a tool as more like a sanitizer/run at the LLVM
> IR level rather than as source transformations - but I've not thought about
> it too much & maybe it makes more sense as a real source transformation
> (easier to communicate to the user "this change is not caught by test
> coverage").
>
> (idle thought: Presumably it'd be easier to just add a ! at the top of the
> boolean expression, so transforming "if (date > expiry)" into "if (!(date >
> expiry))")
>
> On Tue, Aug 9, 2016 at 3:02 AM Jonathan Coe via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> I'd like a tool that applies plausible edits to code so I can check if
>> tests pick up the change or not.
>>
>> I think I can do this with a clang-tidy-like framework with a list of
>> mutations (rather than checks).
>>
>> The tool would produce a large list of single-change 'fixes' for
>> clang-apply-fixes to make use of and to be set up as a series of mutated
>> branches for a CI system. Applying mutations to only new code should keep
>> the set manageable.
>>
>> An example mutation would invert `<` in conditionals:
>>
>> `if(date > expiry ) { return 0.0; }`
>>
>> is mutated to
>>
>> `if(date < expiry ) { return 0.0; }`
>>
>> If our tests don't spot this, we have a gap.
>>
>> Is anyone working on, or interested in collaborating on a similar tool?
>>
>> regards,
>>
>> Jon
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>
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