Re: Should basic_*stream::is_open() be const?

[Paolo Carlini <pcarlini at suse dot de>]

Andreas Kohn wrote:

> So, if I read this correctly, "Note that implementers can make this
> change in a binary compatible way by providing both overloads; this
> would be a conforming extension." overloads could be added to libstdc++
> without violating the standard?
>
> Is anything like that planned?
>  
Ok, I'm going to apply the below to mainline (would be 3.5.0 or 4.0), not to
the release branch, however, since we want complete backward and forward
compatibility.

Tested x86-linux.

Paolo.

//////////////////
2004-08-13  Paolo Carlini  <pcarlini@suse.de>

	* include/std/std_fstream.h (class basic_ifstream,
	class basic_ofstream, class basic_fstream): Add const overloads
	of is_open, as per DR 365 [WP].
	* docs/html/ext/howto.html: Add an entry for DR 365.

diff -urN libstdc++-v3-orig/docs/html/ext/howto.html libstdc++-v3/docs/html/ext/howto.html
--- libstdc++-v3-orig/docs/html/ext/howto.html	2004-07-15 20:04:04.000000000 +0200
+++ libstdc++-v3/docs/html/ext/howto.html	2004-08-13 11:26:31.000000000 +0200
@@ -479,6 +479,12 @@
     <dd>Change the format string to &quot;%.0Lf&quot;.
     </dd>
 
+    <dt><a href="lwg-defects.html#365">365</a>:
+        <em>Lack of const-qualification in clause 27</em>
+    </dt>
+    <dd>Add const overloads of <code>is_open</code>.
+    </dd>
+
     <dt><a href="lwg-defects.html#389">389</a>:
         <em>Const overload of valarray::operator[] returns by value</em>
     </dt>
diff -urN libstdc++-v3-orig/include/std/std_fstream.h libstdc++-v3/include/std/std_fstream.h
--- libstdc++-v3-orig/include/std/std_fstream.h	2003-11-16 01:55:51.000000000 +0100
+++ libstdc++-v3/include/std/std_fstream.h	2004-08-13 11:33:51.000000000 +0200
@@ -1,6 +1,6 @@
 // File based streams -*- C++ -*-
 
-// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
+// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
 // Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
@@ -282,7 +282,8 @@
        *  @brief  Returns true if the external file is open.
       */
       bool
-      is_open() const throw() { return _M_file.is_open(); }
+      is_open() const throw()
+      { return _M_file.is_open(); }
 
       /**
        *  @brief  Opens an external file.
@@ -569,7 +570,14 @@
        *  @return  @c rdbuf()->is_open()
       */
       bool
-      is_open() { return _M_filebuf.is_open(); }
+      is_open()
+      { return _M_filebuf.is_open(); }
+
+      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+      // 365. Lack of const-qualification in clause 27
+      bool
+      is_open() const
+      { return _M_filebuf.is_open(); }
 
       /**
        *  @brief  Opens an external file.
@@ -693,7 +701,14 @@
        *  @return  @c rdbuf()->is_open()
       */
       bool
-      is_open() { return _M_filebuf.is_open(); }
+      is_open()
+      { return _M_filebuf.is_open(); }
+
+      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+      // 365. Lack of const-qualification in clause 27
+      bool
+      is_open() const
+      { return _M_filebuf.is_open(); }
 
       /**
        *  @brief  Opens an external file.
@@ -817,7 +832,14 @@
        *  @return  @c rdbuf()->is_open()
       */
       bool
-      is_open() { return _M_filebuf.is_open(); }
+      is_open()
+      { return _M_filebuf.is_open(); }
+
+      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+      // 365. Lack of const-qualification in clause 27
+      bool
+      is_open() const
+      { return _M_filebuf.is_open(); }
 
       /**
        *  @brief  Opens an external file.