[clang] [clang] Add tests for Core issues about friend templates (PR #94288)
via cfe-commits
cfe-commits at lists.llvm.org
Mon Jun 3 15:25:31 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Vlad Serebrennikov (Endilll)
<details>
<summary>Changes</summary>
This patch covers the following Core issues:
[CWG1862](https://cplusplus.github.io/CWG/issues/1862.html) "Determining “corresponding members” for friendship"
[CWG1918](https://cplusplus.github.io/CWG/issues/1918.html) "`friend` templates with dependent scopes"
[CWG1945](https://cplusplus.github.io/CWG/issues/1945.html) "Friend declarations naming members of class templates in non-templates"
All of them were resolved by CWG1862, where the current wording of [[temp.friend] p5](https://eel.is/c++draft/temp.friend#<!-- -->5) comes from:
> A template friend declaration may declare a member of a dependent type to be a friend[.](https://eel.is/c++draft/temp.friend#<!-- -->5.sentence-1) The friend declaration shall declare a function or specify a type with an [elaborated-type-specifier](https://eel.is/c++draft/dcl.type.elab#nt:elaborated-type-specifier), in either case with a [nested-name-specifier](https://eel.is/c++draft/expr.prim.id.qual#nt:nested-name-specifier) ending with a [simple-template-id](https://eel.is/c++draft/temp.names#nt:simple-template-id), C, whose [template-name](https://eel.is/c++draft/temp.names#nt:template-name) names a class template[.](https://eel.is/c++draft/temp.friend#<!-- -->5.sentence-2) The template parameters of the template friend declaration shall be deducible from C ([[temp.deduct.type]](https://eel.is/c++draft/temp.deduct.type))[.](https://eel.is/c++draft/temp.friend#<!-- -->5.sentence-3) In this case, a member of a specialization S of the class template is a friend of the class granting friendship if deduction of the template parameters of C from S succeeds, and substituting the deduced template arguments into the friend declaration produces a declaration that corresponds to the member of the specialization[.](https://eel.is/c++draft/temp.friend#<!-- -->5.sentence-4)
A useful example is provided after the paragraph: https://eel.is/c++draft/temp.friend#example-4.
Neither of Core issues is implemented, because we don't support dependent nested friend specifiers.
---
Full diff: https://github.com/llvm/llvm-project/pull/94288.diff
3 Files Affected:
- (modified) clang/test/CXX/drs/cwg18xx.cpp (+92)
- (modified) clang/test/CXX/drs/cwg19xx.cpp (+39)
- (modified) clang/www/cxx_dr_status.html (+3-3)
``````````diff
diff --git a/clang/test/CXX/drs/cwg18xx.cpp b/clang/test/CXX/drs/cwg18xx.cpp
index b71a81b62f814..054ce5a4f4b70 100644
--- a/clang/test/CXX/drs/cwg18xx.cpp
+++ b/clang/test/CXX/drs/cwg18xx.cpp
@@ -373,6 +373,98 @@ namespace cwg1837 { // cwg1837: 3.3
#endif
}
+namespace cwg1862 { // cwg1862: no
+template<class T>
+struct A {
+ struct B {
+ void e();
+ };
+
+ void f();
+
+ struct D {
+ void g();
+ };
+
+ T h();
+
+ template<T U>
+ T i();
+};
+
+template<>
+struct A<int> {
+ struct B {
+ void e();
+ };
+
+ int f();
+
+ struct D {
+ void g();
+ };
+
+ template<int U>
+ int i();
+};
+
+template<>
+struct A<float*> {
+ int* h();
+};
+
+class C {
+ int private_int;
+
+ template<class T>
+ friend struct A<T>::B;
+ // expected-warning at -1 {{dependent nested name specifier 'A<T>::' for friend class declaration is not supported; turning off access control for 'C'}}
+
+ template<class T>
+ friend void A<T>::f();
+ // expected-warning at -1 {{dependent nested name specifier 'A<T>::' for friend class declaration is not supported; turning off access control for 'C'}}
+
+ // FIXME: this is ill-formed, because A<T>::D does not end with a simple-template-id
+ template<class T>
+ friend void A<T>::D::g();
+ // expected-warning at -1 {{dependent nested name specifier 'A<T>::D::' for friend class declaration is not supported; turning off access control for 'C'}}
+
+ template<class T>
+ friend int *A<T*>::h();
+ // expected-warning at -1 {{dependent nested name specifier 'A<T *>::' for friend class declaration is not supported; turning off access control for 'C'}}
+
+ template<class T>
+ template<T U>
+ friend T A<T>::i();
+ // expected-warning at -1 {{dependent nested name specifier 'A<T>::' for friend class declaration is not supported; turning off access control for 'C'}}
+};
+
+C c;
+
+template<class T>
+void A<T>::B::e() { (void)c.private_int; }
+void A<int>::B::e() { (void)c.private_int; }
+
+template<class T>
+void A<T>::f() { (void)c.private_int; }
+int A<int>::f() { (void)c.private_int; return 0; }
+
+// FIXME: both definition of 'D::g' are not friends, so they don't have access to 'private_int'
+template<class T>
+void A<T>::D::g() { (void)c.private_int; }
+void A<int>::D::g() { (void)c.private_int; }
+
+template<class T>
+T A<T>::h() { (void)c.private_int; }
+int* A<float*>::h() { (void)c.private_int; return 0; }
+
+template<class T>
+template<T U>
+T A<T>::i() { (void)c.private_int; }
+template<int U>
+int A<int>::i() { (void)c.private_int; }
+} // namespace cwg1862
+
namespace cwg1872 { // cwg1872: 9
#if __cplusplus >= 201103L
template<typename T> struct A : T {
diff --git a/clang/test/CXX/drs/cwg19xx.cpp b/clang/test/CXX/drs/cwg19xx.cpp
index 3e4f82813f51b..6085a40b67afb 100644
--- a/clang/test/CXX/drs/cwg19xx.cpp
+++ b/clang/test/CXX/drs/cwg19xx.cpp
@@ -80,6 +80,30 @@ namespace cwg1909 { // cwg1909: 3.7
};
}
+namespace cwg1918 { // cwg1918: no
+template<typename T> struct A {
+ class B {
+ class C {};
+ };
+};
+class X {
+ static int x;
+ // FIXME: this is ill-formed, because A<T>::B::C does not end with a simple-template-id
+ template <typename T>
+ friend class A<T>::B::C;
+ // expected-warning at -1 {{dependent nested name specifier 'A<T>::B::' for friend class declaration is not supported; turning off access control for 'X'}}
+};
+template<> struct A<int> {
+ typedef struct Q B;
+};
+struct Q {
+ class C {
+ // FIXME: 'f' is not a friend, so 'X::x' is not accessible
+ int f() { return X::x; }
+ };
+};
+} // namespace cwg1918
+
namespace cwg1940 { // cwg1940: 3.5
#if __cplusplus >= 201103L
static union {
@@ -121,6 +145,21 @@ derived d2(42, 9);
#endif
}
+namespace cwg1945 { // cwg1945: no
+template<typename T> struct A {
+ class B {
+ class C {};
+ };
+};
+class X {
+ static int x;
+ // FIXME: this is ill-formed, because A<T>::B::C does not end with a simple-template-id
+ template <typename T>
+ friend class A<T>::B::C;
+ // expected-warning at -1 {{dependent nested name specifier 'A<T>::B::' for friend class declaration is not supported; turning off access control for 'X'}}
+};
+} // namespace cwg1918
+
namespace cwg1947 { // cwg1947: 3.5
#if __cplusplus >= 201402L
unsigned o = 0'01; // ok
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index 4d94ac5a1ac1d..e5f79419a9975 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -10980,7 +10980,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/1862.html">1862</a></td>
<td>CD5</td>
<td>Determining “corresponding members” for friendship</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="none" align="center">No</td>
</tr>
<tr id="1863">
<td><a href="https://cplusplus.github.io/CWG/issues/1863.html">1863</a></td>
@@ -11316,7 +11316,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/1918.html">1918</a></td>
<td>CD5</td>
<td><TT>friend</TT> templates with dependent scopes</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="none" align="center">No</td>
</tr>
<tr class="open" id="1919">
<td><a href="https://cplusplus.github.io/CWG/issues/1919.html">1919</a></td>
@@ -11478,7 +11478,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/1945.html">1945</a></td>
<td>CD5</td>
<td>Friend declarations naming members of class templates in non-templates</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="none" align="center">No</td>
</tr>
<tr id="1946">
<td><a href="https://cplusplus.github.io/CWG/issues/1946.html">1946</a></td>
``````````
</details>
https://github.com/llvm/llvm-project/pull/94288
More information about the cfe-commits
mailing list