Test regex match ambiguity (2273)

[zoecarver]

Summary

This patch resolves issue 2273. This patch only adds tests. NFC.

[mclow.lists]

This looks good to me.

[mclow.lists]

Committed (slightly modified) as revision 365080.

test/std/re/re.alg/re.alg.match/basic.pass.cpp

std::locale::global(std::locale("C"));
         assert(m.prefix().second == m[0].first);
         assert(!m.suffix().matched);
         assert(m.suffix().first == m[0].second);
         assert(m.suffix().second == m[0].second);
         assert(m.length(0) == 4);
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+    { // LWG 2273
+        std::regex re("Foo|FooBar");
+        std::cmatch m;
+        {
+            assert(std::regex_match("FooBar", m, re));
+            assert(m.size() == 1);
+            assert(m[0] == "FooBar");
+        }
+        {
+            assert(std::regex_match("Foo", m, re));
+            assert(m.size() == 1);
+            assert(m[0] == "Foo");
+        }
+        {
+            assert(!std::regex_match("FooBarBaz", m, re));
+            assert(m.size() == 0);
+            assert(m.empty());
+        }
+        {
+            assert(!std::regex_match("FooBa", m, re));
+            assert(m.size() == 0);
+            assert(m.empty());
+        }
+    }
 
   return 0;
 }

test/std/re/re.alg/re.alg.search/basic.pass.cpp

std::locale::global(std::locale("C"));
         assert(m.prefix().second == m[0].first);
         assert(!m.suffix().matched);
         assert(m.suffix().first == m[0].second);
         assert(m.suffix().second == m[0].second);
         assert(m.length(0) == 4);
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+    { // LWG 2273
+        std::regex re("Foo|FooBar");
+        std::cmatch m;
+        {
+            assert(std::regex_search("FooBar", m, re));
+            assert(m.size() == 1);
+            assert(m[0] == "Foo");
+        }
+        {
+            assert(std::regex_search("Foo", m, re));
+            assert(m.size() == 1);
+            assert(m[0] == "Foo");
+        }
+        {
+            assert(std::regex_search("FooBarBaz", m, re));
+            assert(m.size() == 1);
+            assert(m[0] == "Foo");
+        }
+        {
+            assert(std::regex_search("FooBa", m, re));
+            assert(m.size() == 1);
+            assert(m[0] == "Foo");
+        }
+    }
 
   return 0;
 }

www/cxx1z_status.html

<!--   <I>Note: "NAD" means that the issue was deemed "Not a defect"</I> -->
   <tr><td><a href="https://wg21.link/LWG2156">2156</a></td><td>Unordered containers' <tt>reserve(n)</tt> reserves for <tt>n-1</tt> elements</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2218">2218</a></td><td>Unclear how containers use <tt>allocator_traits::construct()</tt></td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2219">2219</a></td><td><tt><i>INVOKE</i></tt>-ing a pointer to member with a <tt>reference_wrapper</tt> as the object expression</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2224">2224</a></td><td>Ambiguous status of access to non-live objects</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2234">2234</a></td><td><tt>assert()</tt> should allow usage in constant expressions</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2244">2244</a></td><td>Issue on <tt>basic_istream::seekg</tt></td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2250">2250</a></td><td>Follow-up On Library Issue 2207</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2259">2259</a></td><td>Issues in 17.6.5.5 rules for member functions</td><td>Kona</td><td>Complete</td></tr>
-  <tr><td><a href="https://wg21.link/LWG2273">2273</a></td><td><tt>regex_match</tt> ambiguity</td><td>Kona</td><td></td></tr>
+  <tr><td><a href="https://wg21.link/LWG2273">2273</a></td><td><tt>regex_match</tt> ambiguity</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2336">2336</a></td><td><tt>is_trivially_constructible/is_trivially_assignable</tt> traits are always false</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2353">2353</a></td><td><tt>std::next</tt> is over-constrained</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2367">2367</a></td><td><tt>pair</tt> and <tt>tuple</tt> are not correctly implemented for <tt>is_constructible</tt> with no args</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2380">2380</a></td><td>May <tt>&lt;cstdlib&gt;</tt> provide <tt>long ::abs(long)</tt> and <tt>long long ::abs(long long)</tt>?</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2384">2384</a></td><td>Allocator's <tt>deallocate</tt> function needs better specification</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2385">2385</a></td><td><tt>function::assign</tt> allocator argument doesn't make sense</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2435">2435</a></td><td><tt>reference_wrapper::operator()</tt>'s Remark should be deleted</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2447">2447</a></td><td>Allocators and <tt>volatile</tt>-qualified value types</td><td>Kona</td><td>Complete</td></tr>