[cfe-dev] How to get argument names from clang::CallExpr?

[Yitzhak Mandelbaum via cfe-dev]

Can you show use the code corresponding to the CallExpr?

Also, when you say the "name of the first argument supplied..." that
presumes that the first argument is always a variable. That's not generally
the case -- any (well typed) argument will work. For example, your first
argument in the dumped CallExpr above is pointer-dereference (I think
`*valueString`?).  So, you would, at the least, want your code to be

if (const auto *dr = clang::dyn_cast<clang::DeclRefExpr>(expr->getArg(0))) {

  auto name = dr->getDecl()->getName().str();

  ...

}


That said, you probably want expr->IgnoringImplicit(), since lvalues (e.g.
variable names) are always implicitly cast to rvalues.



On Thu, Oct 24, 2019 at 3:29 AM Kenth Eriksson via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> > What if you don't try to cast it to a `DeclRefExpr`, but you cast it
> > to
> > a `Expr` and `->dump()` it?
> >
>
> If I dump the CallExpr, I can see the following;
>
> CallExpr 0x5640de2c08c8 'char *'
> |-ImplicitCastExpr 0x5640de2c08b0 'char *(*)(char *, const char *)'
> <FunctionToPointerDecay>
> | `-DeclRefExpr 0x5640de2c07f0 'char *(char *, const char *)' Function
> 0x5640de2916a8 'strcpy' 'char *(char *, const char *)'
> |-ImplicitCastExpr 0x5640de2c08f8 'char *' <LValueToRValue>
> | `-UnaryOperator 0x5640de2c0848 'char *' lvalue prefix '*' cannot overflow
> |   `-ImplicitCastExpr 0x5640de2c0830 'char **' <LValueToRValue>
> |     `-DeclRefExpr 0x5640de2c0810 'char **' lvalue ParmVar 0x5640de366998
> 'valueString' 'char **'
> `-ImplicitCastExpr 0x5640de2c0928 'const char *' <NoOp>
>   `-ImplicitCastExpr 0x5640de2c0910 'char *' <LValueToRValue>
>     `-DeclRefExpr 0x5640de2c0860 'char *' lvalue Var 0x5640de366d88 'ptr1'
> 'char *'
>
> I want to get the name of the first argument supplied to the call of
> strcpy.
>
> Note that some args are not represented by `DeclRefExpr` if they are
> > literals such as IntegerLiteral or StringLiteral.
> >
>
>
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