rsmith added inline comments.
================
Comment at: clang/lib/Sema/TreeTransform.h:11940-11943
- ExprResult Callee = getDerived().TransformExpr(E->getCallee());
- if (Callee.isInvalid())
- return ExprError();
-
----------------
Fznamznon wrote:
> cor3ntin wrote:
> > I don't understand why we would not need to transform the callee. do we do
> > that elsewhere?
> For example, the code above for call and subscript operators never transforms
> the callee.
> This `TransFormExpr` call seems to be a no-op for overloaded operator call
> case, and the result never ends up in the resulting ast.
>
To me it looks like we need to transform the callee in order to transform the
declarations in the `UnresolvedLookupExpr`, if the operator has such functions.
For example, in:
```
namespace A {
template<typename T> T f(T t) {
T operator+(T, T);
return t + t;
}
}
namespace B {
struct X {};
}
void g(B::X x) { A::f(x); }
```
... we need to transform the `UnresolvedLookupExpr` for the `t + t` to map from
the `operator+` declaration in the `A::f` template to the instantiated
`operator+` declaration in `A::f<B::X>`.
But I think this patch is going in the right direction. We don't *actually*
want to transform the callee; all we want to do is to transform the function or
list of functions contained in the callee to form an `UnresolvedSet` of
candidates found during the template parse. Building and then throwing away a
`DeclRefExpr` or `UnresolvedLookupExpr` denoting that function or set of
functions is both a waste of time and (as demonstrated by the bug being
addressed here) problematic.
Instead of calling `TransformExpr` on the callee, we should be calling
`TransformOverloadExprDecls` if the callee is an `UnresolvedLookupExpr` or
`TransformDecl` if it's a `DeclRefExpr`, and I think
`RebuildCXXOperatorCallExpr` should be changed to take an `UnresolvedSet` and a
`RequiresADL` flag, and it looks like we can then remove the `OrigCallee`
parameter, if we pass in some extra source locations.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D151553/new/
https://reviews.llvm.org/D151553
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