[cfe-dev] Getting function body from CallExpr (function definition in .h, implementation in .c)

[Himanshu via cfe-dev]

Thanks Matthias and David!

I will try to look into ASTMergeAction.

--
Himanshu

On Tue, Jul 12, 2016 at 11:25 PM, David Come <David.Come at onera.fr> wrote:

> Hi,
>
> The compiler only knows what it has parsed. So unless you parse impl.c and
> then merge the AST, you can't get the function's body C.
>
> Because it is enough for any compiler in main.c to know that  foo is a
> function with no argument returning nothing. Its body is irrelevant for
> compiling main.c to an object file. You could have its source code (like
> you do in your example) or it could be in a library, it only matters when
> linking.
>
> I know the API has some utilities for merging ASTs together
> (ASTMergeAction).
>
>
>
> David.
>
>
>
> Le 2016-07-13 03:45, Himanshu via cfe-dev a écrit :
>
> Hi All,
>
> I have looked thru the previous posts on this topic in the mailing-list
> archives, and still can't get things to work. Hence the repost --- for
> which I apologize.
>
> I would like to get the body of a called function when visiting a
> CallExpr.
> I create a recursive AST visitor, and handle the translation units
> correctly (to the best of my knowledge), and still am not able to get the
> body. The function is declared in a header file and implemented in a .c
> file. For brevity, I am recreating a toy example here:
>
> def.h:
>    void foo();
>
> impl.c:
>    #include "def.h"
>
>    void foo(){
>           printf("in func foo\n");
>    }
>
> main.c:
>   #include "def.h"
>
>   int main(){
>      foo();
>   }
>
> Running my Visitor code here is able to parse the call expression, but
> returns nullptr on
> callexpr->getDirectCallee()->getBody(). Similarly,
> callexpr->getDirectCallee()->hasBody()
> returns false.
> Could anyone kindly suggest what should I do?
>
> Here is the simplified code for my visitor:
> class FVisitor : public RecursiveASTVisitor<FVisitor> {
>    public:
>           bool VisitCallExpr(CallExpr *C){
>                 const FunctionDecl *FD = C->getDirectCallee();
>                 // try both variants of getBody
>                 if(FD->getBody())
>                             cout << "found body"<<endl;
>                 else if(FD->getBody(FD))
>                            cout << "found body"<<endl;
>                 return true;
>           }
> };
>
> Thanks,
> --
> Himanshu
>
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>
>
> --
> David Come
>
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