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3b639d7d1d
Given the following invalid code,
```cpp
template <class T>
struct S {
T *a;
};
S s = {1};
```
we produce such diagnostics currently:
```
<source>:2:8: note: candidate template ignored: could not match 'S<T>' against 'int'
2 | struct S {
| ^
<source>:2:8: note: candidate template ignored: could not match 'T *' against 'int'
```
Which I think is confusing because there's no `S<T>` nor `T *` at the
location it points to. This is because we're deducing the initializer
against implicitly generated deduction guides, and their source
locations just point to the corresponding `RecordDecl`. Hence the
misleading notes.
This patch alleviates the issue by adding extra notes demonstrating
which implicit deduction guide we're deducing against. In other words,
in addition to the note of `could not match 'T *' against 'int'`, we
would also say the implicit deduction guide we're trying to use:
`template <class T> S(T *) -> S<T>`, which looks clearer IMO.
---------
Co-authored-by: Sirraide <aeternalmail@gmail.com>
76 lines
2.1 KiB
C++
76 lines
2.1 KiB
C++
// RUN: %clang_cc1 -std=c++17 -verify %s
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namespace pr41427 {
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template <typename T> class A {
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public:
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A(void (*)(T)) {}
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};
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void D(int) {}
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void f() {
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A a(&D);
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using T = decltype(a);
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using T = A<int>;
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}
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}
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namespace Access {
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struct B {
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protected:
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struct type {};
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};
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template<typename T> struct D : B { // expected-note {{not viable}} \
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expected-note {{implicit deduction guide declared as 'template <typename T> D(D<T>) -> D<T>'}}
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D(T, typename T::type); // expected-note {{private member}} \
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// expected-note {{implicit deduction guide declared as 'template <typename T> D(T, typename T::type) -> D<T>'}}
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};
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D b = {B(), {}};
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class X {
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using type = int;
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};
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D x = {X(), {}}; // expected-error {{no viable constructor or deduction guide}}
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// Once we implement proper support for dependent nested name specifiers in
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// friends, this should still work.
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class Y {
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template <typename T> friend D<T>::D(T, typename T::type); // expected-warning {{dependent nested name specifier}}
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struct type {};
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};
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D y = {Y(), {}};
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class Z {
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template <typename T> friend class D;
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struct type {};
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};
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D z = {Z(), {}};
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}
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namespace GH69987 {
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template<class> struct X {};
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template<class = void> struct X;
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X x;
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template<class T, class B> struct Y { Y(T); };
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template<class T, class B=void> struct Y ;
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Y y(1);
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}
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namespace NoCrashOnGettingDefaultArgLoc {
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template <typename>
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class A {
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A(int = 1); // expected-note {{candidate template ignored: couldn't infer template argumen}} \
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// expected-note {{implicit deduction guide declared as 'template <typename> D(int = <null expr>) -> D<type-parameter-0-0>'}}
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};
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class C : A<int> {
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using A::A;
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};
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template <typename>
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class D : C { // expected-note {{candidate function template not viable: requires 1 argument}} \
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expected-note {{implicit deduction guide declared as 'template <typename> D(D<type-parameter-0-0>) -> D<type-parameter-0-0>'}}
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using C::C;
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};
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D abc; // expected-error {{no viable constructor or deduction guide}}
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}
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