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P1787 <https://wg21.link/p1787>: CWG399 is resolved by explicitly appealing to
the lookup for the last component of any suitable nested-name-specifier.
Wording: Otherwise, its nested-name-specifier N shall nominate a type. If N has
another nested-name-specifier S, Q is looked up as if its lookup context were
that nominated by S. ([basic.lookup.qual]/6.2)
CWG399 revisits a resolution to older CWG244. Our test for CWG244 covers many
examples from CWG399, and it was updated in 2020 presumably aware of P1787
<https://reviews.llvm.org/P1787>, so I reused CWG244 test. This approach to
reusing was discussed in a CWG405 patch review
<https://reviews.llvm.org/D139095>.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D147920
Files:
clang/test/CXX/drs/dr2xx.cpp
clang/test/CXX/drs/dr3xx.cpp
clang/www/cxx_dr_status.html
Index: clang/www/cxx_dr_status.html
===================================================================
--- clang/www/cxx_dr_status.html
+++ clang/www/cxx_dr_status.html
@@ -2433,7 +2433,7 @@
<td><a href="https://wg21.link/cwg399";>399</a></td>
<td>CD6</td>
<td>Destructor lookup redux</td>
- <td class="none" align="center">Unknown</td>
+ <td class="full" align="center">Clang 11</td>
</tr>
<tr id="400">
<td><a href="https://wg21.link/cwg400";>400</a></td>
Index: clang/test/CXX/drs/dr3xx.cpp
===================================================================
--- clang/test/CXX/drs/dr3xx.cpp
+++ clang/test/CXX/drs/dr3xx.cpp
@@ -1435,3 +1435,83 @@
}
}
}
+
+namespace dr399 { // dr399: 11
+ // NB: reuse dr244 test
+ struct B {}; // expected-note {{type 'dr244::B' found by destructor name lookup}}
+ struct D : B {};
+
+ D D_object;
+ typedef B B_alias;
+ B* B_ptr = &D_object;
+
+ void f() {
+ D_object.~B(); // expected-error {{does not match the type 'D' of the object being destroyed}}
+ D_object.B::~B();
+ D_object.D::~B(); // FIXME: Missing diagnostic for this.
+ B_ptr->~B();
+ B_ptr->~B_alias();
+ B_ptr->B_alias::~B();
+ B_ptr->B_alias::~B_alias();
+ B_ptr->dr244::~B(); // expected-error {{refers to a member in namespace}}
+ B_ptr->dr244::~B_alias(); // expected-error {{refers to a member in namespace}}
+ }
+
+ template<typename T, typename U>
+ void f(T *B_ptr, U D_object) {
+ D_object.~B(); // FIXME: Missing diagnostic for this.
+ D_object.B::~B();
+ D_object.D::~B(); // FIXME: Missing diagnostic for this.
+ B_ptr->~B();
+ B_ptr->~B_alias();
+ B_ptr->B_alias::~B();
+ B_ptr->B_alias::~B_alias();
+ B_ptr->dr399::~B(); // expected-error {{does not refer to a type name}}
+ B_ptr->dr399::~B_alias(); // expected-error {{does not refer to a type name}}
+ }
+ template void f<B, D>(B*, D);
+
+ namespace N {
+ template<typename T> struct E {};
+ typedef E<int> F;
+ }
+ void g(N::F f) {
+ typedef N::F G; // expected-note {{found by destructor name lookup}}
+ f.~G();
+ f.G::~E(); // expected-error {{ISO C++ requires the name after '::~' to be found in the same scope as the name before '::~'}}
+ f.G::~F(); // expected-error {{undeclared identifier 'F' in destructor name}}
+ f.G::~G();
+ // This is technically ill-formed; E is looked up in 'N::' and names the
+ // class template, not the injected-class-name of the class. But that's
+ // probably a bug in the standard.
+ f.N::F::~E(); // expected-error {{ISO C++ requires the name after '::~' to be found in the same scope as the name before '::~'}}
+ // This is valid; we look up the second F in the same scope in which we
+ // found the first one, that is, 'N::'.
+ f.N::F::~F();
+ // This is technically ill-formed; G is looked up in 'N::' and is not found.
+ // Rejecting this seems correct, but most compilers accept, so we do also.
+ f.N::F::~G(); // expected-error {{qualified destructor name only found in lexical scope; omit the qualifier to find this type name by unqualified lookup}}
+ }
+
+ // Bizarrely, compilers perform lookup in the scope for qualified destructor
+ // names, if the nested-name-specifier is non-dependent. Ensure we diagnose
+ // this.
+ namespace QualifiedLookupInScope {
+ namespace N {
+ template <typename> struct S { struct Inner {}; };
+ }
+ template <typename U> void f(typename N::S<U>::Inner *p) {
+ typedef typename N::S<U>::Inner T;
+ p->::dr399::QualifiedLookupInScope::N::S<U>::Inner::~T(); // expected-error {{no type named 'T' in}}
+ }
+ template void f<int>(N::S<int>::Inner *); // expected-note {{instantiation of}}
+
+ template <typename U> void g(U *p) {
+ typedef U T;
+ p->T::~T();
+ p->U::~T();
+ p->::dr399::QualifiedLookupInScope::N::S<int>::Inner::~T(); // expected-error {{'T' does not refer to a type name}}
+ }
+ template void g(N::S<int>::Inner *);
+ }
+}
Index: clang/test/CXX/drs/dr2xx.cpp
===================================================================
--- clang/test/CXX/drs/dr2xx.cpp
+++ clang/test/CXX/drs/dr2xx.cpp
@@ -500,6 +500,7 @@
}
namespace dr244 { // dr244: 11
+ // NB: this test is reused by dr399
struct B {}; // expected-note {{type 'dr244::B' found by destructor name lookup}}
struct D : B {};
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