[cfe-dev] Assert in SourceManager::getFileIDSlow()

[Alexei Svitkine]

Why would FD->getTypeSpecStartLoc() be invalid?

-Alexei

On Wed, Aug 26, 2009 at 2:32 AM, Chris Lattner<clattner at apple.com> wrote:
> On Aug 25, 2009, at 12:30 PM, Alexei Svitkine wrote:
>
>> Some more details:
>>
>> The input being parsed doesn't have to start with a function
>> declaration to trigger this assert.
>>
>> Also, removing the assert in question makes ccons work correctly. Any
>> chance this could be fixed?
>>
>> (If it could also be added to the clang 1.0 branch, that would be
>> really appreciated.)
>>
>> Thanks! (Patch is attached.)
>
> Alexei, I don't follow why this is safe or how you're triggering it.  The
> SourceManager sets up the "Source Location namespace" very carefully and "0"
> is not a valid "offset".  0 is a sentinel that indicates a default
> constructed source location.  I think you need to change your client to
> something like this:
>
>
>>>     clang::SourceLocation Loc = FD->getTypeSpecStartLoc();
>>>     if (Loc.isValid() && SM->isFromMainFile(Loc)) {
>
> -Chris
>
>
>>
>> -Alexei
>>
>> On Tue, Aug 25, 2009 at 2:00 PM, Alexei
>> Svitkine<alexei.svitkine at gmail.com> wrote:
>>>
>>> Hi,
>>>
>>> My code is triggering the assert:
>>>
>>>  assert(SLocOffset && "Invalid FileID");
>>>
>>> In SourceManager::getFileIDSlow().
>>>
>>> It happens as a result of calling SM->isFromMainFile(Loc) in some
>>> ASTConsumer code that looks like:
>>>
>>> void HandleTopLevelDecl(clang::DeclGroupRef D) {
>>>  for (clang::DeclGroupRef::iterator I = D.begin(), E = D.end(); I != E;
>>> ++I) {
>>>   if (clang::FunctionDecl *FD = dyn_cast<clang::FunctionDecl>(*I)) {
>>>     clang::SourceLocation Loc = FD->getTypeSpecStartLoc();
>>>     if (SM->isFromMainFile(Loc)) {
>>>       // ...
>>>     }
>>>   }
>>>  }
>>> }
>>>
>>> (The input that is being parsed begins with a function declaration.)
>>>
>>> I am not sure how old this issue is, but it makes ccons unusable
>>> (which is quite a shame, since I hoped ccons could work fine with the
>>> clang 1.0 release). Any advice would be appreciated.
>>>
>>> -Alexei
>>>
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>