hubert.reinterpretcast added inline comments.
================
Comment at: lib/AST/ExprCXX.cpp:1478
+ {
+ // We do not want error diagnostics escaping here.
+ Sema::SFINAETrap Trap(S);
----------------
saar.raz wrote:
> faisalv wrote:
> > Hubert: This needs a TODO: the idea is not to drop SFINAE errors, but to
> > avoid instantiation that may trigger errors not in the immediate context of
> > instantiation. The substitution needs to happen piecewise.
> Could you elaborate/give an example where this handling is inappropriate?
Determining satisfaction requires normalization (lazy normalization should be
considered).
The determination of satisfaction then proceeds by handling the left-hand side
of conjunction and disjunction constraints before possibly substituting into
the right-hand side; i.e., there is short-circuiting behaviour.
Example:
```
template <typename T>
concept C = true;
template <typename T>
struct Q { static constexpr T value = nullptr; };
template <typename T>
requires C<T> || T::value
struct A { };
template <typename T>
requires C<T> || Q<T>::value
struct B { };
A<int> a; // okay
B<int> b; // okay
```
Repository:
rC Clang
https://reviews.llvm.org/D41217
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