[cfe-dev] check whether a `case` statement has a `break` statement?

[Matthieu Monrocq]

On Wed, Jan 2, 2013 at 11:23 PM, Nikola Smiljanic <popizdeh at gmail.com>wrote:

> I was under the impression that he's trying to verify that every case has
> an explicit break in order to enforce a coding standard that
> forbids fall-through. But I might be wrong.
>
>
I suppose so too, and I can assure you that `return` does not allow a
fall-through to ensue.

-- Matthieu


> On Thu, Jan 3, 2013 at 4:36 AM, Matthieu Monrocq <
> matthieu.monrocq at gmail.com> wrote:
>
>> You do realize that if someone used a "return" or a "throw" then you will
>> miss this ?
>>
>> -- Matthieu
>>
>> On Wed, Jan 2, 2013 at 10:15 AM, kevinlynx <kevinlynx at gmail.com> wrote:
>>
>>> I only want to know if there's a break between two cases (or between a
>>> case and default). I dump a CastStmt AST, but not found a BreakStmt. That's
>>> why i asked for help here.
>>>
>>>
>>> ------------------ Original ------------------
>>> *From: * "Alexander Kornienko"<alexfh at google.com>;
>>> *Date: * Wed, Jan 2, 2013 10:17 AM
>>> *To: * "kevinlynx"<kevinlynx at gmail.com>; **
>>> *Cc: * "cfe-dev"<cfe-dev at cs.uiuc.edu>; **
>>> *Subject: * Re: [cfe-dev] check whether a `case` statement has a
>>> `break` statement?
>>>
>>> I guess you're trying to do something similar to -Wimplicit-fallthrough
>>> diagnostics. If this is the case, take a look at
>>> http://llvm.org/svn/llvm-project/cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp,
>>> DiagnoseSwitchLabelsFallthrough function. In short: you can use CFG
>>> (control-flow graph) to reason about execution paths, and, for example,
>>> detect if there's an execution path between two case labels.
>>>
>>> If you need something simpler, and just detect if there's any 'break'
>>> somewhere between two case labels (I'm not sure I understand why you would
>>> need this, though), you can just use RecursiveASTVisitor and handle
>>> SwitchStmt, SwitchCase (which can be either CaseStmt or DefaultStmt)and BreakStmt.
>>>
>>> On Tue, Jan 1, 2013 at 3:30 PM, kevinlynx <kevinlynx at gmail.com> wrote:
>>>
>>>> In my parser, I get a `SwitchStmt`, and I can traverse all `case`
>>>> statements of it. I want to check whether a `case` statement has a `break`
>>>> statement.. But i can not figure it out. Here is my codes:
>>>>
>>>>
>>>> for (SwitchCase *c = stmt->getSwitchCaseList(); c != NULL; c =
>>>> c->getNextSwitchCase()) {
>>>> if (isa<CaseStmt>(c)) {
>>>> CaseStmt *caseStmt = cast<CaseStmt>(c)
>>>> // I do not know how to check `CaseStmt` has a `BreakStmt`
>>>> }
>>>> }
>>>>
>>>> Thanks.
>>>>
>>>> BTW, I'm writing a static c code analyzer recently, this tool will
>>>> check a number of c coding style rules for c codes. And because I'm a
>>>> newbie to clang, so there will be more newbie questions coming, i'm sorry
>>>> if i bother you guys.
>>>>
>>>>
>>>
>>> --
>>> Regards,
>>> Alexander Kornienko
>>>
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>>
>>>
>>
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