[clang] Add test for CWG1894 and CWG2199

[Endill]

Summary

P1787: CWG1894 and its duplicate CWG2199 are resolved per Richard’s proposal for “dr407 still leaves open questions about typedef / tag hiding”, using generic conflicting-declaration rules even for typedef, and discarding a redundant typedef-name when looking up an elaborated-type-specifier.
Wording: See changes to [dcl.typedef], [basic.lookup.elab], and [basic.lookup]/4.

Generic conflicting-declaration rules are specified in changes to [basic.scope.scope]. CWG407, CWG1894, and CWG2199 discuss how elaborated type specifiers interact with typedefs, using directives, and using declarations. Since existing test for CWG407 covers examples provided in CWG1894 and CWG2199, and does it in accordance with P1787, I reused parts of it.

[cor3ntin]

clang/test/CXX/drs/dr18xx.cpp

172–227

I think i would prefer reusing verbatim the example in 1894 - lines 207 and following basically - as the issue clearly state that what comes before is resolved by 407 so not really relevant here

[Endill]

Thank you for taking a look at this.

clang/test/CXX/drs/dr18xx.cpp

172–227

Does the same apply to 2199? It also contains examples resolved by 407.

[cor3ntin]

clang/test/CXX/drs/dr18xx.cpp

172–227

Yes, i think so. That way it better shows what is actually resolved / tested - amd avoid to much duplication

[cor3ntin]

clang/www/cxx_dr_status.html

13004

I would just say "Yes", i think clang 3.8 predates these issues

[Endill]

clang/www/cxx_dr_status.html

13004

It's not the case: 2199 was filed 12.11.2015, but 3.8 was released on 08.03.2016.

[erichkeane]

clang/www/cxx_dr_status.html

13004

I don't think that is a policy we have anyway. We frequently just say "this has worked since Clang X.X" even with much more recent DRs than the release.

[Endill]

clang/www/cxx_dr_status.html

13004

Yes, up until now I'd just throw tests into compiler explorer, and look when clang started behaving the way it does today. I say "Yes" upon hitting 3.0, which is the oldest available.

[Endill]

Remove parts of CWG1894 and CWG2199 tests that are resolved by CWG407

[cor3ntin]

LGTM, thanks!

clang/www/cxx_dr_status.html

13004

Got it, thanks!

[Endill]

rebase

clang/test/CXX/drs/dr18xx.cpp

 #if __cplusplus <= 201703L
   // expected-error@-3 {{copy assignment operator is implicitly deleted}}
   // expected-error@-3 {{copy assignment operator is implicitly deleted}}
 #endif
   b = b; // expected-error {{copy assignment operator is implicitly deleted}}
   b = static_cast<B&&>(b); // expected-error {{copy assignment operator is implicitly deleted}}
 #endif
 }
+
+namespace dr1894 { // dr1894: 3.8
+                   // NB: reusing part of dr407 test
+namespace A {
+  struct S {};
+}
+namespace B {
+  typedef int S;
+}
+namespace E {
+  typedef A::S S;
+  using A::S;
+  struct S s;
+}
+namespace F {
+  typedef A::S S;
+}
+namespace G {
+  using namespace A;
+  using namespace F;
+  struct S s;
+}
+namespace H {
+  using namespace F;
+  using namespace A;
+  struct S s;
+}
+}

clang/test/CXX/drs/dr21xx.cpp

 // RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// 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++2b -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 dr2100 { // dr2100: 12
   template<const int *P, bool = true> struct X {};

 #if __cplusplus < 201103L
   B &B::operator=(const B&) = default; // expected-error {{private member}} expected-error {{extension}} expected-note {{here}}
   B &B::operator=(B&&) = default; // expected-error {{private member}} expected-error 2{{extension}} expected-note {{here}}
 #else
   B &B::operator=(const B&) = default; // expected-error {{would delete}} expected-note@-9{{inaccessible copy assignment}}
   B &B::operator=(B&&) = default; // expected-error {{would delete}} expected-note@-10{{inaccessible move assignment}}
 #endif
 }
+
+namespace dr2199 { // dr2199: 3.8
+                   // NB: reusing part of dr407 test
+namespace A {
+  struct S {};
+}
+namespace B {
+  typedef int S;
+}
+namespace E {
+  typedef A::S S;
+  using A::S;
+  struct S s;
+}
+namespace F {
+  typedef A::S S;
+}
+namespace G {
+  using namespace A;
+  using namespace F;
+  struct S s;
+}
+namespace H {
+  using namespace F;
+  using namespace A;
+  struct S s;
+}
+}

clang/test/CXX/drs/dr4xx.cpp

typedef struct {
     static int n; // expected-error {{static data member 'n' not allowed in anonymous struct}}
   } A;
   typedef union {
     static int n; // expected-error {{static data member 'n' not allowed in anonymous union}}
   } B;
 }
 
 namespace dr407 { // dr407: 3.8
+                  // NB: reused by dr1894 and dr2199
   struct S;
   typedef struct S S;
   void f() {
     struct S *p;
     {
       typedef struct S S; // expected-note {{here}}
       struct S *p; // expected-error {{typedef 'S' cannot be referenced with a struct specifier}}
     }

clang/www/cxx_dr_status.html

<tr id="1893">
     <td>CD5</td>
     <td>Function-style cast with <I>braced-init-list</I>s and empty pack expansions</td>
     <td class="none" align="center">Unknown</td>
   </tr>
   <tr id="1894">
     <td><a href="https://wg21.link/cwg1894">1894</a></td>
     <td>CD6</td>
     <td><I>typedef-name</I>s and <I>using-declaration</I>s</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="full" align="center">Clang 3.8</td>
   </tr>
   <tr id="1895">
     <td><a href="https://wg21.link/cwg1895">1895</a></td>
     <td>CD4</td>
     <td>Deleted conversions in conditional operator operands</td>
     <td class="none" align="center">Unknown</td>
   </tr>
   <tr id="1896">
<tr id="2198">
     <td>C++17</td>
     <td>Linkage of enumerators</td>
     <td class="none" align="center">Unknown</td>
   </tr>
   <tr id="2199">
     <td><a href="https://wg21.link/cwg2199">2199</a></td>
     <td>CD6</td>
     <td>Typedefs and tags</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="full" align="center">Clang 3.8</td>
   </tr>
   <tr id="2200">
     <td><a href="https://wg21.link/cwg2200">2200</a></td>
     <td>NAD</td>
     <td>Conversions in template argument deduction</td>
     <td class="none" align="center">Unknown</td>
   </tr>
   <tr id="2201">