[cfe-dev] Distinguish in the AST constant array declarations which size is set directly and by the initializer.

[Paolo Bolzoni]

On Wed, 18 Feb 2009 01:28:50 -0800
Eli Friedman <eli.friedman at gmail.com> wrote:

> On Wed, Feb 18, 2009 at 12:59 AM, Paolo Bolzoni <bolzoni at cs.unipr.it> wrote:
> > Visiting the clang AST, is there a way to distinguish between the arrays
> > a1 and a2 and the two unnamed objects whose address will be stored in p1
> > and p2?
> 
> No, we don't distinguish those cases at the moment.  Patches welcome,
> I guess, but I'm not sure where the best place to note it would be.
> -Eli

About arrays, I noticed there was still one free bit pattern (2 bit
allocated, 3 possible size modifiers) so I added NormalImplicit
size modifier that has the same meaning of Normal but indicates that the size
was implicitly defined by the initialiser.

When Sema::AddInitializerToDecl notices the change of type from VariableArray
to ConstantArray it creates a new array type with NormalImplicit as size
modifier.

Here is code:

if (ConstantArrayType* T = cast<ConstantArrayType>(DclT.getTypePtr())) {
  if(isa<IncompleteArrayType>(SavT.getTypePtr())) {
    assert(T-> getSizeModifier() == ArrayType::Normal);
    DclT = Context.getConstantArrayType(T->getElementType(),
                                        T->getSize(),
                                        ArrayType::NormalImplicit,
                                        T->getIndexTypeQualifier());
    ConstantArrayType* T1 = cast<ConstantArrayType>(DclT.getTypePtr());
    assert(T1-> getSizeModifier() == ArrayType::NormalImplicit);
  }
}

Unfortunately, it happens that the second assert fails because
getConstantArrayType returns the previous QualType instead of a new one.
This is caused by the fact that two constant array types are considered
identical no matter the storage class.

I enclosed a patch to this message, it should work using patch -p0 in
the llvm directory.


A real code example where you can see the problem is this one:

void f(int b[5][static 5]);
int a[5][5];

the size storage `static' appears also in the latter array definition.

Thanks,
pb
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