[cfe-dev] matcher acting wierd,imho

[Aaron Ballman via cfe-dev]

On Mon, Nov 7, 2016 at 4:02 PM, Farzad Sadeghi <thabogre at gmail.com> wrote:
> thank you. that actually solves my problem but still doesnt explain
> why the matcher i wrote wasnt matching anything at all.
> hasDescendant(ifStmt()) is true for the first "if".
> hasElse(anything()) is also true and unless(hasAncestor(ifStmt())) is
> also true. and theyre all arguments to a "allOf()" so technically the
> first "if" should be matched and binded by root. am i mistaken
> somewhere?

I've not checked out the behavior of your matcher in the debugger, but
what I am guessing is:

ifStmt( allOf( hasDescendant(ifStmt()), hasElse(anything()),
unless(hasAncestor(ifStmt())) ) )

I think that this does not match the top-level if statement because
hasDescendant(ifStmt()) will not be satisfied -- the top-level if
statement has no sub statements that are also an if statement. It
does, however, have a sub statement that is an else statement. I
notice that the matcher does match the top-level if statement when you
remove the hasDescendant() bit from the query, FWIW.

~Aaron

>
> On 11/7/16, Aaron Ballman <aaron at aaronballman.com> wrote:
>> On Mon, Nov 7, 2016 at 4:03 AM, Farzad Sadeghi via cfe-dev
>> <cfe-dev at lists.llvm.org> wrote:
>>> I have  a simple `if-else if` code I'm trying to match but clang-query
>>> or clang itself match nothing.
>>> here's the C code:
>>> void myfunc (void)
>>> {
>>>         int a = 0U;
>>>         int b = 10U;
>>>
>>>         if (a == b)
>>>         {
>>>                 a++;
>>>         }
>>>         else if (a > b )
>>>         {
>>>                 b++;
>>>         }
>>>
>>> }
>>>
>>> and this is my matcher:
>>> ifStmt( allOf( hasDescendant(ifStmt()), hasElse(anything()) ,
>>> unless(hasAncestor(ifStmt())) ) )
>>>
>>> clang-query and clang don't match anything. Am i assuming wrong that I
>>> should get one match or I'm misunderstanding something here?
>>
>> I think the matcher you may want is:
>>
>> clang-query> m ifStmt(hasElse(ifStmt().bind("else if")))
>>
>> Match #1:
>>
>> E:\Desktop\test.c:10:14: note: "else if" binds here
>>         else if (a > b )
>>              ^~~~~~~~~~~
>> E:\Desktop\test.c:6:9: note: "root" binds here
>>         if (a == b)
>>         ^~~~~~~~~~~
>> 1 match.
>>
>> However, it depends on what code pattern you're trying to match. This
>> matcher assumes you're looking for else if statements (which "else if"
>> binds to, while "root" binds to the if statement that the else
>> statement matches).
>>
>> ~Aaron
>>
>>>
>>> --
>>> Farzad Sadeghi
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>
>
> --
> Farzad Sadeghi