[cfe-dev] using clang - getting type for C variable declaration

[Rajendra]

Hi,

Actually, my question is more about getting type as string from Expr or 
QualType.

Say I have,
       QualType declQT = valueDecl->getType();
or
       QualType lhsQT = lhs->getType();  // lhs is on Expr* type

Now, I want to call QualType.getAsString(PrintingPolicy &Policy) and I 
need compiler instance or AST context to get printing policy, how to get 
compiler instance or AST context here?
       //compilerInstance_ptr?
       clang::ASTContext &context = 
compilerInstance_ptr->getASTContext();
       std::cerr << "\ttype: " << 
declQT.getAsString(context.getPrintingPolicy()) << "\n";

Using Decl, I could do this like decl->getASTContext(); - but same I 
cannot do here!

I am overriding method bool VisitBinAssign(BinaryOperator *E);

Rajendra

On 09-11-2012 09:48 PM, David Blaikie wrote:
> On Fri, Nov 9, 2012 at 2:12 AM, Rajendra <rks at cse.iitb.ac.in> wrote:
>> Hi,
>>
>> 1) I need to get type as string from Expr object. Any pointers?
>
> Presumably Expr::getType():
> 
> http://clang.llvm.org/doxygen/classclang_1_1Expr.html#a3dd8850a4ad8a5b5f595dd9e9446187b
>
>>
>>   Expr* lhs = E->getLHS();
>>
>>   if (strcmp(lhs->getStmtClassName(), "DeclRefExpr") == 0)
>>   {
>>     // get name and type for Expr *lhs from DeclRefExpr
>>     const DeclRefExpr *declRefExpr = dyn_cast<DeclRefExpr>(lhs);
>
> The usual way we write these last two lines is:
>
> if (const DeclRefExpr *declRefExpr = dyn_cast<DeclRefExpr(lhs))
>
> no string comparison required
> no double-check (the string check and then the check in the dyn_cast)
>
> For more details on LLVM's casting machinery:
> http://llvm.org/docs/ProgrammersManual.html#isa
>
>>
>>     const ValueDecl *valueDecl = declRefExpr->getDecl();
>>
>>     if (valueDecl)
>
> Just a stylistic point related to my first (in case you're planning 
> to
> be a Clang/LLVM contributor): we usually collapse the variable
> declaration into the condition.
>
>>     {
>>       std::cerr << "\tLHS identifier = " << 
>> valueDecl->getNameAsString() <<
>> "\n"; // this gives x
>>
>>       QualType declQT = valueDecl->getType();
>>       std::cerr << "\tqual type: ";
>>       declQT.dump();  // this prints  : int identifier
>>
>>       // now call QualType.getAsString(PrintingPolicy &Policy)
>>       // ---> how to get compiler instance and AST context? <---- //
>>       clang::ASTContext &context = 
>> compilerInstance_ptr->getASTContext();
>>       std::cerr << "\ttype: " <<
>> declQT.getAsString(context.getPrintingPolicy()) << "\n";
>>     }
>>   }
>>
>> 2) Here is how I got things right for Decl :) this will be helpful 
>> for
>> others as well.
>>
>>
>>   clang::DeclGroupRef::iterator it;
>>
>>   for (it = declGroupRef.begin(); it != declGroupRef.end(); it++)
>>   {
>>     clang::Decl* decl = *it;
>>
>>     const NamedDecl *namedDecl = dyn_cast<NamedDecl>(decl);
>>
>>     if (namedDecl)
>>     {
>>       std::cerr << "\tidentifier name = "
>>         << namedDecl->getNameAsString() << "\n";
>>     }
>>
>>     const ValueDecl *valueDecl = dyn_cast<ValueDecl>(decl);
>>
>>     if (valueDecl)
>>     {
>>       QualType declQT = valueDecl->getType();
>>
>>       // now call QualType.getAsString(PrintingPolicy &Policy)
>>       clang::ASTContext &context = decl->getASTContext();
>>       std::cerr << "\ttype = " <<
>> declQT.getAsString(context.getPrintingPolicy()) << "\n";
>>
>>     }
>>   }
>>
>>
>> Rajendra
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