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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>
132 lines
3.1 KiB
C++
132 lines
3.1 KiB
C++
// RUN: %clang_cc1 -std=c++2a -include %s %s -ast-print -verify | FileCheck %s
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//
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// RUN: %clang_cc1 -std=c++2a -emit-pch %s -o %t-cxx2a
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// RUN: %clang_cc1 -std=c++2a -include-pch %t-cxx2a %s -ast-print -verify | FileCheck %s
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// RUN: %clang_cc1 -std=c++2a -emit-pch -fpch-instantiate-templates %s -o %t-cxx2a
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// RUN: %clang_cc1 -std=c++2a -include-pch %t-cxx2a %s -ast-print -verify | FileCheck %s
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#ifndef USE_PCH
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namespace inheriting_constructor {
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struct S {};
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template<typename X, typename Y> struct T {
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template<typename A>
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explicit(((void)Y{}, true)) T(A &&a) {}
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};
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template<typename X, typename Y> struct U : T<X, Y> {
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using T<X, Y>::T;
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};
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U<S, char> foo(char ch) {
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return U<S, char>(ch);
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}
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}
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#else
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namespace inheriting_constructor {
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U<S, char> a = foo('0');
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}
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//CHECK: explicit(((void)char{} , true))
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#endif
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namespace basic {
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#ifndef USE_PCH
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struct B {};
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struct A {
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explicit A(int);
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explicit(false) operator bool();
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explicit(true) operator B();
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};
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#else
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//expected-note@-6+ {{candidate constructor}}
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//expected-note@-9+ {{candidate constructor}}
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//expected-note-re@-7+ {{explicit constructor is not a candidate{{$}}}}
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//expected-note@-7+ {{candidate function}}
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//expected-note@-7+ {{explicit conversion function is not a candidate (explicit specifier evaluates to true)}}
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//CHECK: explicit{{ +}}A(
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//CHECK-NEXT: explicit(false){{ +}}operator
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//CHECK-NEXT: explicit(true){{ +}}operator
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A a = 0; //expected-error {{no viable conversion}}
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A a1(0);
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bool b = a1;
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B b1 = a1; //expected-error {{no viable conversion}}
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#endif
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}
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namespace templ {
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#ifndef USE_PCH
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template<bool b>
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struct B {
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static constexpr bool value = b;
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};
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template<bool b>
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struct A {
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explicit(b) A(B<b>) {}
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template<typename T>
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explicit(b ^ T::value) operator T();
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};
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B<true> b_true;
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B<false> b_false;
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#else
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//expected-note@-8 {{candidate template ignored}} expected-note@-8 {{implicit deduction guide declared as 'template <bool b> A(A<b>) -> A<b>'}}
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//expected-note@-8 {{explicit constructor declared here}} expected-note@-8 {{implicit deduction guide declared as 'template <bool b> explicit(b) A(B<b>) -> A<b>'}}
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//expected-note@-15+ {{candidate constructor}}
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//expected-note@-8+ {{explicit conversion function is not a candidate (explicit specifier}}
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//expected-note@-11 {{explicit constructor is not a candidate (explicit specifier}}
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//CHECK: explicit(b){{ +}}A
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//CHECK: explicit(b{{ +}}^{{ +}}T::value){{ +}}operator
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A a = { b_true }; //expected-error {{class template argument deduction}}
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A a0 = b_true; //expected-error {{no viable constructor or deduction guide}}
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A a_true(b_true);
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A a_false = b_false;
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B<true> b = a_true;
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B<true> b1 = a_false; //expected-error {{no viable conversion}}
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B<false> b2(a_true);
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#endif
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}
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namespace guide {
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#ifndef USE_PCH
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template<typename T>
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struct A {
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A(T);
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};
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template<typename T>
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explicit(true) A(T) -> A<T>;
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explicit(false) A(int) -> A<int>;
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#else
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//expected-note@-5 {{explicit deduction guide}}
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//CHECK: explicit(true){{ +}}A(
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//CHECK: explicit(false){{ +}}A(
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A a = { 0.0 }; //expected-error {{explicit deduction guide}}
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A a1 = { 0 };
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#endif
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}
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#define USE_PCH
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