Re: [PATCH] improve string find algorithm

[Jonathan Wakely <jwakely at redhat dot com>]

On 06/01/17 20:32 +0000, Jonathan Wakely wrote:
> On 06/01/17 13:35 +0000, Jonathan Wakely wrote:
> > I'm surprised we don't have any tests for this case, but apparently we
> > don't, as your patch passes all our tests.
>
> My bad, we do have tests that FAIL with this patch, but only after a
> 'make clean' (otherwise the explicit instantiation definitions in the
> library don't get rebuilt after applying the patch, so the tests use
> the old code).
>
> FAIL: 21_strings/basic_string/operations/find/char/1.cc execution test
> FAIL: 21_strings/basic_string/operations/find/wchar_t/1.cc execution test
>
> These fail on assert(s.find(s, 1) == std::string::npos) which gives
> the wrong answer as explained in my previous mail.
>
> The infinite loop caused by this patch isn't caught by any existing
> tests, so I'll add a check for that.

Committed to trunk.

commit b81b226d9eb336f205e5ac91fb8ab4bbbfaf2cb8
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Jan 6 21:20:57 2017 +0000

    Add more tests for std::basic_string::find
    
    	* testsuite/21_strings/basic_string/operations/find/char/6.cc: New.
    	* testsuite/21_strings/basic_string/operations/find/wchar_t/6.cc: New.

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/find/char/6.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/find/char/6.cc
new file mode 100644
index 0000000..6925fbb
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/find/char/6.cc
@@ -0,0 +1,41 @@
+// 2017-01-06  Jonathan Wakely  <jwakely@redhat.com>
+
+// Copyright (C) 2017 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 3, 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 COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// C++11 21.4.7.2 [string::find] basic_string find
+
+#include <string>
+#include <testsuite_hooks.h>
+
+// https://gcc.gnu.org/ml/libstdc++/2017-01/msg00021.html
+void test01()
+{
+  typedef std::string string_type;
+  string_type::size_type npos = string_type::npos;
+
+  string_type use = "aaa";
+  string_type::size_type pos1 = use.find("ab");
+
+  VERIFY( pos1 == npos );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/find/wchar_t/6.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/find/wchar_t/6.cc
new file mode 100644
index 0000000..eb3463d
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/find/wchar_t/6.cc
@@ -0,0 +1,41 @@
+// 2017-01-06  Jonathan Wakely  <jwakely@redhat.com>
+
+// Copyright (C) 2017 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 3, 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 COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// C++11 21.4.7.2 [string::find] basic_string find
+
+#include <string>
+#include <testsuite_hooks.h>
+
+// https://gcc.gnu.org/ml/libstdc++/2017-01/msg00021.html
+void test01()
+{
+  typedef std::wstring string_type;
+  string_type::size_type npos = string_type::npos;
+
+  string_type use = L"aaa";
+  string_type::size_type pos1 = use.find(L"ab");
+
+  VERIFY( pos1 == npos );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}