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[Patch] Fix libstdc++/11480
- From: Paolo Carlini <pcarlini at unitus dot it>
- To: libstdc++ at gcc dot gnu dot org
- Date: Tue, 14 Oct 2003 10:59:44 +0200
- Subject: [Patch] Fix libstdc++/11480
Hi,
this took me some time... A little bit of history will help
understanding why I'm now confident that, besides fixing the bug,
I haven't broken anything ;)
Let us consider, for simplicity, the first of the two unique:
__first = std::adjacent_find(__first, __last);
return std::unique_copy(__first, __last, __first);
The bug is that, after adjacent_find, *__first == *++__first and
unique_copy does one redundant, non conforming, comparison.
Therefore, I envisaged fixing the bug like this:
__first = std::adjacent_find(__first, __last);
if (__first == __last)
return __last;
_ForwardIterator __dest = __first;
return std::unique_copy(++__first, __last, __dest);
This does the trick, indeed, but now we are doing one unnecessary
copy right at the beginning of unique_copy.
However, we are almost there: it suffices to inspect __unique_copy
(the forward_iterator_tag version, of course) to discover that:
*__result = *__first; <<<<<<<<<<<<<<<<<<<
while (++__first != __last)
if (!(*__result == *__first))
*++__result = *__first;
return ++__result;
The unnecessary copy is easily identified! At this point, I have
just copied over the code, removed the first line, renamed a
variable and... that's it.
The same reasoning applies straightforwardly to the binary predicate
version of unique too.
To be safe, I have also added some missing tests to testsuite.
Tested x86-linux, will wait a day or two for comments.
Paolo.
///////////
2003-10-14 Paolo Carlini <pcarlini@unitus.it>
PR libstdc++/11480
* include/bits/stl_algo.h (unique): Fix.
* testsuite/25_algorithms/unique.cc: Move to unique/1.cc.
* testsuite/25_algorithms/unique/11480.cc: New, from the PR.
* testsuite/25_algorithms/unique/2.cc: New.
diff -urN libstdc++-v3-orig/include/bits/stl_algo.h libstdc++-v3/include/bits/stl_algo.h
--- libstdc++-v3-orig/include/bits/stl_algo.h 2003-10-01 22:45:59.000000000 +0200
+++ libstdc++-v3/include/bits/stl_algo.h 2003-10-14 09:23:23.000000000 +0200
@@ -1268,8 +1268,18 @@
__glibcxx_function_requires(_EqualityComparableConcept<
typename iterator_traits<_ForwardIterator>::value_type>)
+ // Skip the beginning, if already unique.
__first = std::adjacent_find(__first, __last);
- return std::unique_copy(__first, __last, __first);
+ if (__first == __last)
+ return __last;
+
+ // Do the real copy work.
+ _ForwardIterator __dest = __first;
+ ++__first;
+ while (++__first != __last)
+ if (!(*__dest == *__first))
+ *++__dest = *__first;
+ return ++__dest;
}
/**
@@ -1297,8 +1307,18 @@
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
+ // Skip the beginning, if already unique.
__first = std::adjacent_find(__first, __last, __binary_pred);
- return std::unique_copy(__first, __last, __first, __binary_pred);
+ if (__first == __last)
+ return __last;
+
+ // Do the real copy work.
+ _ForwardIterator __dest = __first;
+ ++__first;
+ while (++__first != __last)
+ if (!__binary_pred(*__dest, *__first))
+ *++__dest = *__first;
+ return ++__dest;
}
/**
diff -urN libstdc++-v3-orig/testsuite/25_algorithms/unique/1.cc libstdc++-v3/testsuite/25_algorithms/unique/1.cc
--- libstdc++-v3-orig/testsuite/25_algorithms/unique/1.cc 1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/25_algorithms/unique/1.cc 2003-10-14 09:38:43.000000000 +0200
@@ -0,0 +1,32 @@
+// 2001-07-19 Peter Schmid <schmid@snake.iap.physik.tu-darmstadt.de>
+
+// Copyright (C) 2001 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING. If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// 25.2.8 [lib.alg.unique] Unique
+
+#include <list>
+#include <algorithm>
+
+int main()
+{
+ using namespace std;
+ list<int> menge;
+ unique (menge.begin(), menge.end());
+ return 0;
+}
diff -urN libstdc++-v3-orig/testsuite/25_algorithms/unique/11480.cc libstdc++-v3/testsuite/25_algorithms/unique/11480.cc
--- libstdc++-v3-orig/testsuite/25_algorithms/unique/11480.cc 1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/25_algorithms/unique/11480.cc 2003-10-14 09:36:10.000000000 +0200
@@ -0,0 +1,46 @@
+// Copyright (C) 2003 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING. If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+
+int a[10] = { 1, 2, 3, 3, 4, 5, 5, 6, 7, 9 };
+
+static int compare_count = 0;
+
+bool compare(int a, int b)
+{
+ compare_count++;
+ return a == b;
+}
+
+// libstdc++/11480
+void test01()
+{
+ bool test __attribute__((unused)) = true;
+
+ std::unique(a, a+10, compare);
+ VERIFY( compare_count == 9 );
+}
+
+int
+main()
+{
+ test01();
+ return 0;
+}
diff -urN libstdc++-v3-orig/testsuite/25_algorithms/unique/2.cc libstdc++-v3/testsuite/25_algorithms/unique/2.cc
--- libstdc++-v3-orig/testsuite/25_algorithms/unique/2.cc 1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/25_algorithms/unique/2.cc 2003-10-14 10:19:18.000000000 +0200
@@ -0,0 +1,98 @@
+// 2003-10-14 Paolo Carlini <pcarlini@unitus.it>
+
+// Copyright (C) 2003 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING. If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// 25.2.8 [lib.alg.unique] Unique
+
+#include <list>
+#include <algorithm>
+#include <functional>
+#include <testsuite_hooks.h>
+
+const int T1[] = {1, 4, 4, 6, 1, 2, 2, 3, 1, 6, 6, 6, 5, 7, 5, 4, 4};
+const int T2[] = {1, 1, 1, 2, 2, 1, 1, 7, 6, 6, 7, 8, 8, 8, 8, 9, 9};
+const int N = sizeof(T1) / sizeof(int);
+
+const int A1[] = {1, 4, 6, 1, 2, 3, 1, 6, 5, 7, 5, 4};
+const int A2[] = {1, 4, 4, 6, 6, 6, 6, 7};
+const int A3[] = {1, 1, 1};
+
+const int B1[] = {1, 2, 1, 7, 6, 7, 8, 9};
+const int B2[] = {1, 1, 1, 2, 2, 7, 7, 8, 8, 8, 8, 9, 9};
+const int B3[] = {9, 9, 8, 8, 8, 8, 7, 6, 6, 1, 1, 1, 1, 1};
+
+void test01()
+{
+ bool test __attribute__((unused)) = true;
+ using namespace std;
+
+ list<int>::iterator pos;
+
+ list<int> coll(T1, T1 + N);
+ pos = unique(coll.begin(), coll.end());
+ VERIFY( equal(coll.begin(), pos, A1) );
+
+ list<int> coll2(T2, T2 + N);
+ pos = unique(coll2.begin(), coll2.end());
+ VERIFY( equal(coll2.begin(), pos, B1) );
+}
+
+void test02()
+{
+ bool test __attribute__((unused)) = true;
+ using namespace std;
+
+ list<int>::iterator pos;
+
+ list<int> coll(T1, T1 + N);
+ pos = unique(coll.begin(), coll.end(), greater<int>());
+ VERIFY( equal(coll.begin(), pos, A2) );
+
+ list<int> coll2(T2, T2 + N);
+ pos = unique(coll2.begin(), coll2.end(), greater<int>());
+ VERIFY( equal(coll2.begin(), pos, B2) );
+}
+
+void test03()
+{
+ bool test __attribute__((unused)) = true;
+ using namespace std;
+
+ list<int>::iterator pos;
+
+ list<int> coll(T1, T1 + N);
+ pos = unique(coll.begin(), coll.end(), less<int>());
+ VERIFY( equal(coll.begin(), pos, A3) );
+
+ list<int> coll2(T2, T2 + N);
+ reverse(coll2.begin(), coll2.end());
+ pos = unique(coll2.begin(), coll2.end(), less<int>());
+ VERIFY( equal(coll2.begin(), pos, B3) );
+}
+
+int main()
+{
+ test01();
+ test02();
+ test03();
+ return 0;
+}
+
+
+
diff -urN libstdc++-v3-orig/testsuite/25_algorithms/unique.cc libstdc++-v3/testsuite/25_algorithms/unique.cc
--- libstdc++-v3-orig/testsuite/25_algorithms/unique.cc 2001-07-20 03:17:13.000000000 +0200
+++ libstdc++-v3/testsuite/25_algorithms/unique.cc 1970-01-01 01:00:00.000000000 +0100
@@ -1,34 +0,0 @@
-// 2001-07-19 Peter Schmid <schmid@snake.iap.physik.tu-darmstadt.de>
-
-// Copyright (C) 2001 Free Software Foundation, Inc.
-//
-// This file is part of the GNU ISO C++ Library. This library is free
-// software; you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the
-// Free Software Foundation; either version 2, or (at your option)
-// any later version.
-
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License along
-// with this library; see the file COPYING. If not, write to the Free
-// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
-// USA.
-
-// 25.2.8 Unique
-
-
-#include <list>
-#include <algorithm>
-
-
-int main()
-{
- using namespace std;
- list<int> menge;
- unique (menge.begin(), menge.end());
- return 0;
-}