[cfe-dev] Few questions related to type checking in clang

[Reid Kleckner]

On Tue, Sep 2, 2014 at 11:30 PM, Amila Jayasekara <thejaka.amila at gmail.com>
wrote:

> Hi Nikola,
>
> Thanks a lot for the response.
>
>
> On Wed, Sep 3, 2014 at 1:56 AM, Nikola Smiljanic <popizdeh at gmail.com>
> wrote:
>
>> 1. Sema is responsible for building the ast, after doing all the checks.
>> Act methods are 'hooks' that Parser uses to call into Sema. Build methods
>> are used to build the actual ast nodes.
>>
>> 2. Various declaration classes have methods that return QualType, see
>> http://clang.llvm.org/docs/InternalsManual.html#the-qualtype-class. So
>> VarDecl has getType but FunctionDecl in addtion has getReturnType and
>> getFunctionType, etc.
>>
>
> I am actually looking for the class which contains all VarDecl's for a
> program. As an example, if I have a program as follows;
>
> int a;
> bool b;
> ...
> ...
>
> I am assuming there is a some sort of a container in clang which keeps all
> declaration data.
> Suppose the container is named as TypeEnvironment for the moment. Then I
> need to query type information about each declaration with code similar to
> following;
>
> TypeEnvironment.get("a")
> TypeEnvironment.get("b")
>
> etc ...
>
> So I am looking for the closest implementation in clang, which gives me
> the functionality of TypeEnvironment (in example above).
>

Clang AST types are attached to the Decl involved. So you would find a's
Decl and say something like ADecl->getType(), which is a QualType, which
can be examined in many ways.

If you just want to do name lookup, the closest thing to what you are
thinking of is a DeclContext. Lots of things like functions, namespaces,
classes, unions, etc are DeclContexts, and the lookup is complicated. For
example, you can find a type from a base class. You would use
Sema::LookupQualifiedName to find what you want, probably. There can be
many results of varying kind, and you would have to consider all cases.
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