r207696 - PR19601: std::remove_if does not really remove the elements.

Thu May 1 07:47:50 PDT 2014

I modified the test so that it now catches all cases:

   - no remove_if (and thus no erase) : fail
   - remove_if : fail
   - remove_if + erase : pass

The test is however not robust in face of appending more options in the
stripPositionalArgs : for now it has the minimal number of
'-no-integrated-as' to catch the issues we have had, and we could add some
more to have a reasonnable margin. Thoughts ?

Cheers,
--
Arnaud

On Thu, May 1, 2014 at 2:57 AM, Richard Smith <richard at metafoo.co.uk> wrote:

> On Wed, Apr 30, 2014 at 4:31 PM, Arnaud Allard de Grandmaison <
> arnaud.adegm at gmail.com> wrote:
>
>> Dumping Args before & after the remove_if shows that Jordan is right:
>>  - before: Args: clang-tool -target x86_64 -no-integrated-as -c -v -c
>> placeholder.cpp
>>  - after: Args: clang-tool -target x86_64 -c -v -c placeholder.cpp
>> placeholder.cpp
>> and later on, _all_ input files are dropped. So we were just lucky.
>>
>> The code in stripPositionalArgs appends some arguments (-c
>> placeholder.cpp), so I can not force -no-integrated-as to be last from the
>> command line.
>>
>>  This would require to adapt stripPositionalArgs so that it prepends its
>> arguments and we can test for the missing erase. Do we still want a
>> testcase for that ? It seems a bit like an overshoot to me, but I aggree
>> that there as been several incorrect commits in the same place.
>>
>
> Easier test: add -no-integrated-as *repeatedly*. If you add it enough
> times, it'll be in the tail of unchanged elements left behind by remove_if.
>
>
>> On Thu, May 1, 2014 at 12:46 AM, Richard Smith <richard at metafoo.co.uk>wrote:
>>
>>> On Wed, Apr 30, 2014 at 3:40 PM, Arnaud Allard de Grandmaison <
>>> arnaud.adegm at gmail.com> wrote:
>>>
>>>> I have not been able to come up with a testcase which does better than
>>>> what test/Tooling/multi-jobs.cpp already does.
>>>>
>>>> The current test status:
>>>>  1. no remove_if (and thus no erase) : multi-jobs fails
>>>>  2. remove_if : multi-jobs pass
>>>>  3. remove_if + erase : multi-jobs pass
>>>>
>>>> Invoking clang-check with '-v' shows that in cases 2 & 3 the
>>>> -no-integrated-as has been dropped. I feel a bit like hunting a red herring
>>>> there : depending on the argument position, it gets dropped or not.
>>>> Jordan's hypothesis is probably right.
>>>>
>>>
>>> Try putting it at the end of the command line.
>>>
>>>
>>>>  Cheers,
>>>> --
>>>> Arnaud
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Wed, Apr 30, 2014 at 11:30 PM, Jordan Rose <jordan_rose at apple.com>wrote:
>>>>
>>>>> My hypothesis for how this was working: std::remove_if reorders
>>>>> elements using std::move, so we were getting lucky that -no-integrated-as
>>>>> wasn't the last argument and something else got moved on top of it. We'd
>>>>> have duplicates of the last few arguments (because they got moved earlier),
>>>>> but that wouldn't show -no-integrated-as.
>>>>>
>>>>> Jordan
>>>>>
>>>>>
>>>>> On Apr 30, 2014, at 14:09, Richard Smith <richard at metafoo.co.uk>
>>>>> wrote:
>>>>>
>>>>> This needs a test case. This code has already been committed,
>>>>> incorrectly, twice before this revision; the existing test case clearly
>>>>> doesn't actually cover it properly.
>>>>>
>>>>>
>>>>> On Wed, Apr 30, 2014 at 12:59 PM, Arnaud A. de Grandmaison <
>>>>> arnaud.adegm at gmail.com> wrote:
>>>>>
>>>>>> Author: aadg
>>>>>> Date: Wed Apr 30 14:59:22 2014
>>>>>> New Revision: 207696
>>>>>>
>>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=207696&view=rev
>>>>>> Log:
>>>>>> PR19601: std::remove_if does not really remove the elements.
>>>>>>
>>>>>> It moves them at the end of the range instead, so an extra erase is
>>>>>> needed.
>>>>>>
>>>>>> It is strange that this code works without the erase. On the other
>>>>>> hand, removing the remove_if will make fail some tests.
>>>>>>
>>>>>> Modified:
>>>>>>     cfe/trunk/lib/Tooling/CompilationDatabase.cpp
>>>>>>
>>>>>> Modified: cfe/trunk/lib/Tooling/CompilationDatabase.cpp
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Tooling/CompilationDatabase.cpp?rev=207696&r1=207695&r2=207696&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- cfe/trunk/lib/Tooling/CompilationDatabase.cpp (original)
>>>>>> +++ cfe/trunk/lib/Tooling/CompilationDatabase.cpp Wed Apr 30 14:59:22
>>>>>> 2014
>>>>>> @@ -238,8 +238,9 @@ static bool stripPositionalArgs(std::vec
>>>>>>
>>>>>>    // Remove -no-integrated-as; it's not used for syntax checking,
>>>>>>    // and it confuses targets which don't support this option.
>>>>>> -  std::remove_if(Args.begin(), Args.end(),
>>>>>> -                 MatchesAny(std::string("-no-integrated-as")));
>>>>>> +  Args.erase(std::remove_if(Args.begin(), Args.end(),
>>>>>> +
>>>>>>  MatchesAny(std::string("-no-integrated-as"))),
>>>>>> +             Args.end());
>>>>>>
>>>>>>    const std::unique_ptr<driver::Compilation> Compilation(
>>>>>>        NewDriver->BuildCompilation(Args));
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> cfe-commits mailing list
>>>>>> cfe-commits at cs.uiuc.edu
>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
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