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>
57 lines
2.6 KiB
C++
57 lines
2.6 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx23,precxx17 %std_cxx98-14 %s
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// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx23,cxx17 %std_cxx17-20 %s
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// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx17,cxx23 %std_cxx23- %s
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template<typename T, typename U = float> struct A { };
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typedef A<int> A_int;
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typedef float FLOAT;
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A<int, FLOAT> *foo(A<int> *ptr, A<int> const *ptr2, A<int, double> *ptr3) {
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if (ptr)
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return ptr; // okay
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else if (ptr2)
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return ptr2; // precxx23-error{{cannot initialize return object of type 'A<int, FLOAT> *' (aka 'A<int, float> *') with an lvalue of type 'const A<int> *'}} \
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cxx23-error{{cannot initialize return object of type 'A<int, FLOAT> *' (aka 'A<int, float> *') with an rvalue of type 'const A<int> *'}}
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else {
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return ptr3; // precxx23-error{{cannot initialize return object of type 'A<int, FLOAT> *' (aka 'A<int, float> *') with an lvalue of type 'A<int, double> *'}} \
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cxx23-error{{cannot initialize return object of type 'A<int, FLOAT> *' (aka 'A<int, float> *') with an rvalue of type 'A<int, double> *'}}
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}
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}
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template<int I> struct B;
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const int value = 12;
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B<17 + 2> *bar(B<(19)> *ptr1, B< (::value + 7) > *ptr2, B<19 - 3> *ptr3) {
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if (ptr1)
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return ptr1;
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else if (ptr2)
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return ptr2;
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else
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return ptr3; // precxx23-error{{cannot initialize return object of type 'B<17 + 2> *' with an lvalue of type 'B<19 - 3>}} \
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cxx23-error{{cannot initialize return object of type 'B<17 + 2> *' with an rvalue of type 'B<19 - 3>}}
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}
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typedef B<5> B5;
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namespace N {
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template<typename T> struct C {};
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}
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N::C<int> c1;
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typedef N::C<float> c2;
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// PR5655
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template<typename T> struct Foo { }; // precxx17-note {{template is declared here}} \
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cxx17-note {{candidate template ignored: couldn't infer template argument 'T'}} \
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cxx17-note {{implicit deduction guide declared as 'template <typename T> Foo() -> Foo<T>'}} \
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cxx17-note {{implicit deduction guide declared as 'template <typename T> Foo(Foo<T>) -> Foo<T>'}} \
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cxx17-note {{candidate function template not viable: requires 1 argument, but 0 were provided}}
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void f(void) { Foo bar; } // precxx17-error {{use of class template 'Foo' requires template arguments}} \
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cxx17-error {{no viable constructor or deduction guide for deduction of template arguments of 'Foo'}}
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template <typename T> class Party;
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template <> class Party<T> { friend struct Party<>; }; // expected-error {{use of undeclared identifier 'T'}}
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