[cfe-dev] VarDecl hierarchy (Re: Objective-C tidy up)

[Steve Naroff]

On Jun 9, 2008, at 9:00 AM, David Chisnall wrote:

>
> On 8 Jun 2008, at 18:42, Chris Lattner wrote:
>
>> On Jun 8, 2008, at 10:30 AM, David Chisnall wrote:
>>>>> It should be working now (does for me, at least...).  Assignments
>>>>> to self were failing because implicit params are not valdecls and
>>>>> I missed a test.
>>>>
>>>> Getting closer!  We now just have the NSString.m failure:
>>>>
>>>> /Users/sabre/llvm/tools/clang/lib/Analysis/../../include/clang/
>>>> Analysis/Visitors/CFGRecStmtDeclVisitor.h:66: failed assertion
>>>> `false && "Subtype of ScopedDecl not handled."'
>>>
>>> I think this is fixed, but since this test only runs on OS X I
>>> can't test it...
>>
>> Thanks!  This gets it onto the next assertion:
>>
>> /Users/sabre/llvm/tools/clang/lib/Analysis/../../include/clang/
>> Analysis/Support/ExprDeclBitVector.h:41: failed assertion `isValid()'
>>
>> Here's a .mi file.  Run with -checker-cfref -verify.
>>
>> <NSString.mi.gz>
>>
>>
>> It would probably be useful to grep for other uses of VarDecl and
>> ParamVarDecl to see if the code applies to self as well.  There may
>> be other codepaths not being exercised by the testsuite.
>
> It seems that there are a lot of bits of the analyses that assume
> VarDecls.  This is a bit messy, since ParmVarDecls, as VarDecl
> subclasses, store a SClass which is always None and their Init pointer
> is always 0.
>

I don't believe this is true. For example, "register" is a legal  
storage class for parms.

In addition, the Init pointer will come in handy for C++ (default  
arguments).

snaroff

> This makes me wonder why ParmVarDecls are VarDecl subclasses, since
> they never actually use any of the extra state declared in VarDecl as
> far as I can see.
>
> I'm not sure what the best approach here is.  I could make
> ImplicitParamDecl a subclass of VarDecl, which would waste a bit of
> space in every one (the same space that's wasted in ParmVarDecls).
> Changing every bit of code in the analyses that thinks it wants a
> VarDecl to expect a ValueDecl and dyn_cast it to a VarDecl when it
> actually wanted to use it as one would require some quite invasive
> changes to the code.
>
> Suggestions?
>
> David
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