Iterating over AST node objects


If I dump() a clang::Type object, I can see this AST representation -

ConstantArrayType 0x555562830ea0 ‘const char **const [0]’ 0
-QualType 0x555562830c81 'const char **const' const -PointerType 0x555562830c80 ‘const char **’
-PointerType 0x5555627ed2a0 'const char *' -QualType 0x5555627ec7d1 ‘const char’ const
`-BuiltinType 0x5555627ec7d0 ‘char’

Is there a way to use the ASTContext to iterate over each node? (Do each of those lines represent a node?)

My motivation is to get the inner most PointerType object.


Yes those lines represent nodes. You do not necessarily need ASTContext to look at a node’s descendants: you can just use the node’s methods.

Were these sugar (= syntax-only) type nodes, you could iterate over the child of each successive node via desugar(), and successively desugar while searching for a Type subclass T via getAs<T>().

But pointee types/array element types are of course not sugar: they are distinct semantic entities, so desugar/getAs won’t will not pass through them. Hence your problem.

Fortunately there seems to be a getPointeeOrArrayElementType() to help peel off the semantic layers you want to look through, analogous to desugar() — but unfortunately there is not a getAs analog for this case, so you have to write the search manually.

Something like this should work (not tested):

PointerType *getInnermostPointerType(const Type *T) {
const PointerType *res = nullptr;

while (true) {
const Type *pointeeOrElement = T->getPointeeOrArrayElementType();
if (pointeeOrElement == T)
// T is neither a pointer nor array type: we’re done.

// T is a pointer or array type.
if (isa<PointerType>(T))
res = cast<PointerType>(T);

// iterate T, keep looking
T = pointeeOrElement;
return res;