[clang] [clang][AST] Handle dependent representation of call to function with explicit object parameter in CallExpr::getBeginLoc() (PR #126868)

[Younan Zhang via cfe-commits]

================
@@ -1648,8 +1648,11 @@ SourceLocation CallExpr::getBeginLoc() const {
   if (const auto *Method =
           dyn_cast_if_present<const CXXMethodDecl>(getCalleeDecl());
       Method && Method->isExplicitObjectMemberFunction()) {
-    assert(getNumArgs() > 0 && getArg(0));
-    return getArg(0)->getBeginLoc();
+    if (!isTypeDependent()) {
----------------
zyn0217 wrote:

Can we move the `isTypeDependent()` check up to the point where we check `isExplicitObjectMemberFunction()`, and add a FIXME explaining why this only applies to non-dependent call expressions?

i.e.
```cpp
// FIXME: Dependent call expressions are not handled because ...
if (!isTypeDependent()) {
  ...
}
```

https://github.com/llvm/llvm-project/pull/126868