[cfe-dev] (no subject)

[Aitor San Juan]

Hello,

In a checker I want to test whether an argument to a function call is a
String literal, but I'm a bit stuck. Could anybody shed a bit of light on
this?

1. This way seems to not work (although no compile-time error), but I don't
understand why:

const Expr *arg = CE->getArg(0); // CE is a CallExpr
if ((arg != NULL) && (clang::isa<clang::StringLiteral>(arg))){
...

2. The following does not compile:

const Expr *arg = CE->getArg(0); // CE is a CallExpr
if (StringLiteral *SL = dyn_cast<StringLiteral>(arg)) {

invalid conversion from ‘llvm::cast_retty<clang::StringLiteral, const
clang::Expr*>::ret_type {aka const clang::StringLiteral*}’ to
‘clang::StringLiteral*’ [-fpermissive]
    if (StringLiteral *SL = dyn_cast<StringLiteral>(arg)) {
                                                                           ^
3. The following does not compile, however there's a non-const getArg()
method:

Expr *arg = CE->getArg(0); // CE is a CallExpr
if (StringLiteral *SL = dyn_cast<StringLiteral>(arg)) {

error: invalid conversion from ‘const clang::Expr*’ to ‘clang::Expr*’
[-fpermissive]
    Expr *arg = CE->getArg(0);
                            ^
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