re PR libstdc++/51558 (Declaration of unspecialized std::hash<_Tp>::operator()(_Tp) turns compile-time errors into link-time errors)

2011-12-15  Paolo Carlini  <paolo.carlini@oracle.com>
	    Jonathan Wakely  <jwakely.gcc@gmail.com>

	PR libstdc++/51558
	* include/bits/functional_hash.h (struct hash): Add static_assert.
	* src/compatibility-c++0x.cc: Adjust compatibility definitions.
	* testsuite/23_containers/unordered_map/erase/51142.cc: Adjust.
	* testsuite/23_containers/unordered_set/erase/51142.cc: Likewise.
	* testsuite/23_containers/unordered_multimap/erase/51142.cc: Likewise.
	* testsuite/23_containers/unordered_multiset/erase/51142.cc: Likewise.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r182392

7 files changed, 75 insertions, 27 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 38e0ff2..f050ad9 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,14 @@
+2011-12-15  Paolo Carlini  <paolo.carlini@oracle.com>
+	    Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	PR libstdc++/51558
+	* include/bits/functional_hash.h (struct hash): Add static_assert.
+	* src/compatibility-c++0x.cc: Adjust compatibility definitions.
+	* testsuite/23_containers/unordered_map/erase/51142.cc: Adjust.
+	* testsuite/23_containers/unordered_set/erase/51142.cc: Likewise.
+	* testsuite/23_containers/unordered_multimap/erase/51142.cc: Likewise.
+	* testsuite/23_containers/unordered_multiset/erase/51142.cc: Likewise.
+
 2011-12-15  Benjamin Kosnik  <bkoz@redhat.com>
 
 	* testsuite/22_locale/num_put/put/char/9780-2.cc: Add test for "C"
diff --git a/libstdc++-v3/include/bits/functional_hash.h b/libstdc++-v3/include/bits/functional_hash.h
index 2b82b21..e892159 100644
--- a/libstdc++-v3/include/bits/functional_hash.h
+++ b/libstdc++-v3/include/bits/functional_hash.h
@@ -57,8 +57,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Tp>
     struct hash : public __hash_base<size_t, _Tp>
     {
-      size_t
-      operator()(_Tp __val) const;
+      static_assert(sizeof(_Tp) < 0,
+		    "std::hash is not specialized for this type");
+      size_t operator()(const _Tp&) const noexcept;
     };
 
   /// Partial specializations for pointer types.
diff --git a/libstdc++-v3/src/compatibility-c++0x.cc b/libstdc++-v3/src/compatibility-c++0x.cc
index c5e1db0..03c58d2 100644
--- a/libstdc++-v3/src/compatibility-c++0x.cc
+++ b/libstdc++-v3/src/compatibility-c++0x.cc
@@ -52,36 +52,60 @@ namespace std _GLIBCXX_VISIBILITY(default)
 
 #ifndef _GLIBCXX_LONG_DOUBLE_COMPAT_IMPL
   template<>
-    size_t
-    hash<string>::operator()(string __s) const
-    { return _Hash_impl::hash(__s.data(), __s.length()); }
+    struct hash<string>
+    {
+      size_t operator()(string) const;
+    };
+
+  size_t
+  hash<string>::operator()(string __s) const
+  { return _Hash_impl::hash(__s.data(), __s.length()); }
 
   template<>
-    size_t
-    hash<const string&>::operator()(const string& __s) const
-    { return _Hash_impl::hash(__s.data(), __s.length()); }
+    struct hash<const string&>
+    {
+      size_t operator()(const string&) const;
+    };
+
+  size_t
+  hash<const string&>::operator()(const string& __s) const
+  { return _Hash_impl::hash(__s.data(), __s.length()); }
 
 #ifdef _GLIBCXX_USE_WCHAR_T
   template<>
-    size_t
-    hash<wstring>::operator()(wstring __s) const
-    { return _Hash_impl::hash(__s.data(), __s.length() * sizeof(wchar_t)); }
+    struct hash<wstring>
+    { 
+      size_t operator()(wstring) const;
+    };
+
+  size_t
+  hash<wstring>::operator()(wstring __s) const
+  { return _Hash_impl::hash(__s.data(), __s.length() * sizeof(wchar_t)); }
 
   template<>
-    size_t
-    hash<const wstring&>::operator()(const wstring& __s) const
-    { return _Hash_impl::hash(__s.data(), __s.length() * sizeof(wchar_t)); }
+    struct hash<const wstring&>
+    {
+      size_t operator()(const wstring&) const;
+    };
+
+  size_t
+  hash<const wstring&>::operator()(const wstring& __s) const
+  { return _Hash_impl::hash(__s.data(), __s.length() * sizeof(wchar_t)); }
 #endif
 #endif
 
   template<>
-    size_t
-    hash<error_code>::operator()(error_code __e) const
+    struct hash<error_code>
     {
-      const size_t __tmp = std::_Hash_impl::hash(__e._M_value);
-      return std::_Hash_impl::__hash_combine(__e._M_cat, __tmp);
-    }
+      size_t operator()(error_code) const;
+    };
 
+  size_t
+  hash<error_code>::operator()(error_code __e) const
+  {
+    const size_t __tmp = std::_Hash_impl::hash(__e._M_value);
+    return std::_Hash_impl::__hash_combine(__e._M_cat, __tmp);
+  }
 
   // gcc-4.7.0
   // <chrono> changes is_monotonic to is_steady.
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_map/erase/51142.cc b/libstdc++-v3/testsuite/23_containers/unordered_map/erase/51142.cc
index eab637d..7986fb2 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_map/erase/51142.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_map/erase/51142.cc
@@ -27,12 +27,15 @@ struct X
   X(T&) {}
 };
 
+struct X_hash
+{ std::size_t operator()(const X&) const { return 0; } };
+
 bool operator==(const X&, const X&) { return false; }
 
 // LWG 2059.
-void erasor(std::unordered_map<X, int>& s, X x)
+void erasor(std::unordered_map<X, int, X_hash>& s, X x)
 {
-  std::unordered_map<X, int>::iterator it = s.find(x);
+  std::unordered_map<X, int, X_hash>::iterator it = s.find(x);
   if (it != s.end())
     s.erase(it);
 }
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_multimap/erase/51142.cc b/libstdc++-v3/testsuite/23_containers/unordered_multimap/erase/51142.cc
index 678aa5d..0d434ac 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_multimap/erase/51142.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_multimap/erase/51142.cc
@@ -27,12 +27,15 @@ struct X
   X(T&) {}
 };
 
+struct X_hash
+{ std::size_t operator()(const X&) const { return 0; } };
+
 bool operator==(const X&, const X&) { return false; }
 
 // LWG 2059.
-void erasor(std::unordered_multimap<X, int>& s, X x)
+void erasor(std::unordered_multimap<X, int, X_hash>& s, X x)
 {
-  std::unordered_multimap<X, int>::iterator it = s.find(x);
+  std::unordered_multimap<X, int, X_hash>::iterator it = s.find(x);
   if (it != s.end())
     s.erase(it);
 }
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_multiset/erase/51142.cc b/libstdc++-v3/testsuite/23_containers/unordered_multiset/erase/51142.cc
index 4db6af0..7a0a183 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_multiset/erase/51142.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_multiset/erase/51142.cc
@@ -27,12 +27,15 @@ struct X
   X(T&) {}
 };
 
+struct X_hash
+{ std::size_t operator()(const X&) const { return 0; } };
+
 bool operator==(const X&, const X&) { return false; }
 
 // LWG 2059.
-void erasor(std::unordered_multiset<X>& s, X x)
+void erasor(std::unordered_multiset<X, X_hash>& s, X x)
 {
-  std::unordered_multiset<X>::iterator it = s.find(x);
+  std::unordered_multiset<X, X_hash>::iterator it = s.find(x);
   if (it != s.end())
     s.erase(it);
 }
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_set/erase/51142.cc b/libstdc++-v3/testsuite/23_containers/unordered_set/erase/51142.cc
index 1486460..ec5aeb1 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_set/erase/51142.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_set/erase/51142.cc
@@ -27,12 +27,15 @@ struct X
   X(T&) {}
 };
 
+struct X_hash
+{ std::size_t operator()(const X&) const { return 0; } };
+
 bool operator==(const X&, const X&) { return false; }
 
 // LWG 2059.
-void erasor(std::unordered_set<X>& s, X x)
+void erasor(std::unordered_set<X, X_hash>& s, X x)
 {
-  std::unordered_set<X>::iterator it = s.find(x);
+  std::unordered_set<X, X_hash>::iterator it = s.find(x);
   if (it != s.end())
     s.erase(it);
 }