[clang] Add test for CWG1710 and related issues

Those issues focus on `template` keyword being optional in certain type-only contexts (base specifiers, member initializers, typename specifiers), as opposed to be disallowed by the grammar, or required by some implementations. GCC accepts all the tests this patch touches since 10, others fail on various tests: https://godbolt.org/z/1M6KE3W1a It should be noted that the wording in [[ https://cplusplus.github.io/CWG/issues/1710.html | 1710 ]] that resolves those issues has been substantially changed by [[ https://wg21.link/p1787 | P1787 ]]. I can't find the post-P1787 wording that covers those issues, but I can't find the intent of changing relevant behavior in P1787 either, so I assume that intent of the 1710 resolution is preserved somewhere. This patch covers the following issues: [[ https://cplusplus.github.io/CWG/issues/314.html | CWG314 ]] [[ https://cplusplus.github.io/CWG/issues/343.html | CWG343 ]] [[ https://cplusplus.github.io/CWG/issues/1710.html | CWG1710 ]] [[ https://cplusplus.github.io/CWG/issues/1794.html | CWG1794 ]] [[ https://cplusplus.github.io/CWG/issues/1812.html | CWG1812 ]] Reviewed By: #clang-language-wg, cor3ntin Differential Revision: https://reviews.llvm.org/D151697
llvm · Jul 11, 2023 · 1bbaabb · 1bbaabb
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commit 1bbaabb
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Showing 4 changed files with 62 additions and 15 deletions.
diff --git a/clang/test/CXX/drs/dr17xx.cpp b/clang/test/CXX/drs/dr17xx.cpp
@@ -1,7 +1,22 @@
 // RUN: %clang_cc1 -std=c++98 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++11 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++14 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++1z %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++20 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++23 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2c %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+
+namespace dr1710 { // dr1710: no
+// FIXME: all of the following is well-formed
+template <typename T> struct D1 : T::template B<int>::template C<int> {};
+template <typename T> struct D2 : T::B<int>::template C<int> {};
+// expected-error@-1 {{use 'template' keyword to treat 'B' as a dependent template name}}
+template <typename T> struct D3 : T::template B<int>::C<int> {};
+// expected-error@-1 {{use 'template' keyword to treat 'C' as a dependent template name}}
+template <typename T> struct D4 : T::B<int>::C<int> {};
+// expected-error@-1 {{use 'template' keyword to treat 'B' as a dependent template name}}
+// expected-error@-2 {{use 'template' keyword to treat 'C' as a dependent template name}}
+} // namespace dr1710
 
 namespace dr1715 { // dr1715: 3.9
 #if __cplusplus >= 201103L
@@ -146,3 +161,18 @@ namespace dr1778 { // dr1778: 9
   static_assert(noexcept(D()), "");
 #endif
 }
+
+namespace dr1794 { // dr1794: yes
+                   // NB: dup 1710
+#if __cplusplus >= 201103L
+template <template <typename> class Template> struct Internal {
+  template <typename Arg> using Bind = Template<Arg>;
+};
+
+template <template <typename> class Template, typename Arg>
+using Instantiate = Template<Arg>;
+
+template <template <typename> class Template, typename Argument>
+using Bind = Instantiate<Internal<Template>::template Bind, Argument>;
+#endif
+} // namespace dr1794
diff --git a/clang/test/CXX/drs/dr18xx.cpp b/clang/test/CXX/drs/dr18xx.cpp
@@ -4,12 +4,23 @@
 // RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++23 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 
 #if __cplusplus < 201103L
 // expected-error@+1 {{variadic macro}}
 #define static_assert(...) __extension__ _Static_assert(__VA_ARGS__)
 #endif
 
+namespace dr1812 { // dr1812: no
+                   // NB: dup 1710
+#if __cplusplus >= 201103L
+template <typename T> struct A {
+  using B = typename T::C<int>;
+  // expected-error@-1 {{use 'template' keyword to treat 'C' as a dependent template name}}
+};
+#endif
+} // namespace dr1812
+
 namespace dr1813 { // dr1813: 7
   struct B { int i; };
   struct C : B {};

diff --git a/clang/test/CXX/drs/dr3xx.cpp b/clang/test/CXX/drs/dr3xx.cpp
@@ -208,14 +208,20 @@ namespace dr313 { // dr313: dup 299 c++11
 #endif
 }
 
-namespace dr314 { // FIXME 314: dup 1710
-  template<typename T> struct A {
-    template<typename U> struct B {};
-  };
-  template<typename T> struct C : public A<T>::template B<T> {
-    C() : A<T>::template B<T>() {}
-  };
-}
+namespace dr314 { // dr314: no
+                  // NB: dup 1710
+template <typename T> struct A {
+  template <typename U> struct B {};
+};
+template <typename T> struct C : public A<T>::template B<T> {
+  C() : A<T>::template B<T>() {}
+};
+template <typename T> struct C2 : public A<T>::B<T> {
+  // expected-error@-1 {{use 'template' keyword to treat 'B' as a dependent template name}}
+  C2() : A<T>::B<T>() {}
+  // expected-error@-1 {{use 'template' keyword to treat 'B' as a dependent template name}}
+};
+} // namespace dr314
 
 // dr315: na
 // dr316: sup 1004
@@ -591,7 +597,7 @@ namespace dr341 {
 
 // dr342: na
 
-namespace dr343 { // FIXME 343: no
+namespace dr343 { // dr343: no
   // FIXME: dup 1710
   template<typename T> struct A {
     template<typename U> struct B {};

diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
@@ -1923,7 +1923,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/314.html">314</a></td>
     <td>C++17</td>
     <td><TT>template</TT> in base class specifier</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="none" align="center">No</td>
   </tr>
   <tr id="315">
     <td><a href="https://cplusplus.github.io/CWG/issues/315.html">315</a></td>
@@ -2097,7 +2097,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/343.html">343</a></td>
     <td>C++17</td>
     <td>Make <TT>template</TT> optional in contexts that require a type</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="none" align="center">No</td>
   </tr>
   <tr id="344">
     <td><a href="https://cplusplus.github.io/CWG/issues/344.html">344</a></td>
@@ -10067,7 +10067,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/1710.html">1710</a></td>
     <td>C++17</td>
     <td>Missing <TT>template</TT> keyword in <I>class-or-decltype</I></td>
-    <td class="none" align="center">Unknown</td>
+    <td class="none" align="center">No</td>
   </tr>
   <tr id="1711">
     <td><a href="https://cplusplus.github.io/CWG/issues/1711.html">1711</a></td>
@@ -10571,7 +10571,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/1794.html">1794</a></td>
     <td>C++17</td>
     <td><TT>template</TT> keyword and alias templates</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="full" align="center">Yes</td>
   </tr>
   <tr id="1795">
     <td><a href="https://cplusplus.github.io/CWG/issues/1795.html">1795</a></td>
@@ -10679,7 +10679,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/1812.html">1812</a></td>
     <td>C++17</td>
     <td>Omission of <TT>template</TT> in a <I>typename-specifier</I></td>
-    <td class="none" align="center">Unknown</td>
+    <td class="none" align="center">No</td>
   </tr>
   <tr id="1813">
     <td><a href="https://cplusplus.github.io/CWG/issues/1813.html">1813</a></td>