From: Jonathan Wakely Date: Tue, 13 Apr 2021 15:30:16 +0000 (+0100) Subject: libstdc++: Remove outdated docs on libg++ and libstdc++-v2 X-Git-Tag: basepoints/gcc-12~103 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=989e512f719a44fafca0030d7b8a1f5bf5f1baf7;p=thirdparty%2Fgcc.git libstdc++: Remove outdated docs on libg++ and libstdc++-v2 The libstdc++-v3 manual doesn't need to document how to use its predecessors. libstdc++-v3/ChangeLog: * doc/xml/manual/backwards_compatibility.xml: Remove porting notes for libg++ and libstdc++-v2, and bibliography. * doc/html/*: Regenerated. --- diff --git a/libstdc++-v3/doc/html/index.html b/libstdc++-v3/doc/html/index.html index 772009a816b7..ed1a05f36f78 100644 --- a/libstdc++-v3/doc/html/index.html +++ b/libstdc++-v3/doc/html/index.html @@ -142,11 +142,7 @@ Existing tests
C++11 Requirements Test Sequence Descriptions -
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
No ios_base
No cout in <ostream.h>, no cin in <istream.h>
Second
Namespace std:: not supported
Illegal iterator usage
isspace from <cctype> is a macro -
No vector::at, deque::at, string::at
No std::char_traits<char>::eof
No string::clear
- Removal of ostream::form and istream::scan - extensions -
No basic_stringbuf, basic_stringstream
Little or no wide character support
No templatized iostreams
Thread safety issues
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace. +
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
Second
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace.
No stream::attach(int fd)
diff --git a/libstdc++-v3/doc/html/manual/appendix.html b/libstdc++-v3/doc/html/manual/appendix.html index 37dee28ff25e..5ed69411eaba 100644 --- a/libstdc++-v3/doc/html/manual/appendix.html +++ b/libstdc++-v3/doc/html/manual/appendix.html @@ -16,11 +16,7 @@ Existing tests
C++11 Requirements Test Sequence Descriptions -
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
No ios_base
No cout in <ostream.h>, no cin in <istream.h>
Second
Namespace std:: not supported
Illegal iterator usage
isspace from <cctype> is a macro -
No vector::at, deque::at, string::at
No std::char_traits<char>::eof
No string::clear
- Removal of ostream::form and istream::scan - extensions -
No basic_stringbuf, basic_stringstream
Little or no wide character support
No templatized iostreams
Thread safety issues
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace. +
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
Second
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace.
No stream::attach(int fd)
diff --git a/libstdc++-v3/doc/html/manual/appendix_porting.html b/libstdc++-v3/doc/html/manual/appendix_porting.html index 3a3334f13cf0..bfecf52a11da 100644 --- a/libstdc++-v3/doc/html/manual/appendix_porting.html +++ b/libstdc++-v3/doc/html/manual/appendix_porting.html @@ -14,11 +14,7 @@ Existing tests
C++11 Requirements Test Sequence Descriptions -
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
No ios_base
No cout in <ostream.h>, no cin in <istream.h>
Second
Namespace std:: not supported
Illegal iterator usage
isspace from <cctype> is a macro -
No vector::at, deque::at, string::at
No std::char_traits<char>::eof
No string::clear
- Removal of ostream::form and istream::scan - extensions -
No basic_stringbuf, basic_stringstream
Little or no wide character support
No templatized iostreams
Thread safety issues
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace. +
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
Second
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace.
No stream::attach(int fd)
diff --git a/libstdc++-v3/doc/html/manual/backwards.html b/libstdc++-v3/doc/html/manual/backwards.html index 5116ae94bcd6..f52e09d7dc2c 100644 --- a/libstdc++-v3/doc/html/manual/backwards.html +++ b/libstdc++-v3/doc/html/manual/backwards.html @@ -8,7 +8,7 @@ that it had a working relationship with at least two kinds of dinosaur.

Some background: libg++ was designed and created when there was no ISO standard to provide guidance. Classes like linked lists are now -provided for by list<T> and do not need to be +provided for by std::list<T> and do not need to be created by genclass. (For that matter, templates exist now and are well-supported, whereas genclass (mostly) predates them.)

There are other classes in libg++ that are not specified in the @@ -16,351 +16,24 @@ ISO Standard (e.g., statistical analysis). While there are a lot of really useful things that are used by a lot of people, the Standards Committee couldn't include everything, and so a lot of those “obvious” classes didn't get included. -

Known Issues include many of the limitations of its immediate ancestor.

Portability notes and known implementation limitations are as follows.

No ios_base

At least some older implementations don't have std::ios_base, so you should use std::ios::badbit, std::ios::failbit and std::ios::eofbit and std::ios::goodbit. -

No cout in <ostream.h>, no cin in <istream.h>

- In earlier versions of the standard, - <fstream.h>, - <ostream.h> - and <istream.h> - used to define - cout, cin and so on. ISO C++ specifies that one needs to include - <iostream> - explicitly to get the required definitions. -

Some include adjustment may be required.

This project is no longer maintained or supported, and the sources -archived. For the desperate, -the GCC extensions -page describes where to find the last libg++ source. The code is -considered replaced and rewritten. -

Second

+

That project is no longer maintained or supported, and the sources +archived. For the desperate, the +ftp.gnu.org +server still has the libg++ source. +

Second

The second generation GNU C++ library was called libstdc++, or libstdc++-v2. It spans the time between libg++ and pre-ISO C++ standardization and is usually associated with the following GCC releases: egcs 1.x, gcc 2.95, and gcc 2.96.

- The STL portions of this library are based on SGI/HP STL release 3.11. + The STL portions of that library are based on SGI/HP STL release 3.11.

- This project is no longer maintained or supported, and the sources - archived. The code is considered replaced and rewritten. -

- Portability notes and known implementation limitations are as follows. -

Namespace std:: not supported

- Some care is required to support C++ compiler and or library - implementation that do not have the standard library in - namespace std. -

- The following sections list some possible solutions to support compilers - that cannot ignore std::-qualified names. -

- First, see if the compiler has a flag for this. Namespace - back-portability-issues are generally not a problem for g++ - compilers that do not have libstdc++ in std::, as the - compilers use -fno-honor-std (ignore - std::, :: = std::) by default. That is, - the responsibility for enabling or disabling std:: is - on the user; the maintainer does not have to care about it. This - probably applies to some other compilers as well. -

- Second, experiment with a variety of pre-processor tricks. -

- By defining std as a macro, fully-qualified namespace - calls become global. Volia. - 

-#ifdef WICKEDLY_OLD_COMPILER
-# define std
-#endif
-

- Thanks to Juergen Heinzl who posted this solution on gnu.gcc.help. -

- Another pre-processor based approach is to define a macro - NAMESPACE_STD, which is defined to either - “ ” or “std” based on a compile-type - test. On GNU systems, this can be done with autotools by means of - an autoconf test (see below) for HAVE_NAMESPACE_STD, - then using that to set a value for the NAMESPACE_STD - macro. At that point, one is able to use - NAMESPACE_STD::string, which will evaluate to - std::string or ::string (i.e., in the - global namespace on systems that do not put string in - std::). - 

-dnl @synopsis AC_CXX_NAMESPACE_STD
-dnl
-dnl If the compiler supports namespace std, define
-dnl HAVE_NAMESPACE_STD.
-dnl
-dnl @category Cxx
-dnl @author Todd Veldhuizen
-dnl @author Luc Maisonobe <luc@spaceroots.org>
-dnl @version 2004-02-04
-dnl @license AllPermissive
-AC_DEFUN([AC_CXX_NAMESPACE_STD], [
-  AC_CACHE_CHECK(if g++ supports namespace std,
-  ac_cv_cxx_have_std_namespace,
-  [AC_LANG_SAVE
-  AC_LANG_CPLUSPLUS
-  AC_TRY_COMPILE([#include <iostream>
-		  std::istream& is = std::cin;],,
-  ac_cv_cxx_have_std_namespace=yes, ac_cv_cxx_have_std_namespace=no)
-  AC_LANG_RESTORE
-  ])
-  if test "$ac_cv_cxx_have_std_namespace" = yes; then
-    AC_DEFINE(HAVE_NAMESPACE_STD,,[Define if g++ supports namespace std. ])
-  fi
-])
-

Illegal iterator usage

- The following illustrate implementation-allowed illegal iterator - use, and then correct use. -

  • - you cannot do ostream::operator<<(iterator) - to print the address of the iterator => use - operator<< &*iterator instead -

  • - you cannot clear an iterator's reference (iterator = - 0) => use iterator = iterator_type(); -

  • - if (iterator) won't work any more => use - if (iterator != iterator_type()) -

isspace from <cctype> is a macro -

- Glibc 2.0.x and 2.1.x define <ctype.h> functionality as macros - (isspace, isalpha etc.). -

- This implementations of libstdc++, however, keep these functions - as macros, and so it is not back-portable to use fully qualified - names. For example: - 

-#include <cctype>
-int main() { std::isspace('X'); }
-

- Results in something like this: -

-std:: (__ctype_b[(int) ( ( 'X' ) )] & (unsigned short int) _ISspace ) ;
-

- A solution is to modify a header-file so that the compiler tells - <ctype.h> to define functions - instead of macros: -

-// This keeps isalnum, et al from being propagated as macros.
-#if __linux__
-# define __NO_CTYPE 1
-#endif
-

- Then, include <ctype.h> -

- Another problem arises if you put a using namespace - std; declaration at the top, and include - <ctype.h>. This will - result in ambiguities between the definitions in the global namespace - (<ctype.h>) and the - definitions in namespace std:: - (<cctype>). -

No vector::at, deque::at, string::at

- One solution is to add an autoconf-test for this: -

-AC_MSG_CHECKING(for container::at)
-AC_TRY_COMPILE(
-[
-#include <vector>
-#include <deque>
-#include <string>
-
-using namespace std;
-],
-[
-deque<int> test_deque(3);
-test_deque.at(2);
-vector<int> test_vector(2);
-test_vector.at(1);
-string test_string(“test_string”);
-test_string.at(3);
-],
-[AC_MSG_RESULT(yes)
-AC_DEFINE(HAVE_CONTAINER_AT)],
-[AC_MSG_RESULT(no)])
-

- If you are using other (non-GNU) compilers it might be a good idea - to check for string::at separately. -

No std::char_traits<char>::eof

- Use some kind of autoconf test, plus this: -

-#ifdef HAVE_CHAR_TRAITS
-#define CPP_EOF std::char_traits<char>::eof()
-#else
-#define CPP_EOF EOF
-#endif
-

No string::clear

- There are two functions for deleting the contents of a string: - clear and erase (the latter returns the - string). -

-void
-clear() { _M_mutate(0, this->size(), 0); }
-
-basic_string&
-erase(size_type __pos = 0, size_type __n = npos)
-{
-  return this->replace(_M_check(__pos), _M_fold(__pos, __n),
-			  _M_data(), _M_data());
-}
-

- Unfortunately, clear is not implemented in this - version, so you should use erase (which is probably - faster than operator=(charT*)). -

- Removal of ostream::form and istream::scan - extensions -

- These are no longer supported. Please use stringstreams instead. -

No basic_stringbuf, basic_stringstream

- Although the ISO standard i/ostringstream-classes are - provided, (<sstream>), for - compatibility with older implementations the pre-ISO - i/ostrstream (<strstream>) interface is also provided, - with these caveats: -

  • - strstream is considered to be deprecated -

  • - strstream is limited to char -

  • - with ostringstream you don't have to take care of - terminating the string or freeing its memory -

  • - istringstream can be re-filled (clear(); - str(input);) -

- You can then use output-stringstreams like this: -

-#ifdef HAVE_SSTREAM
-# include <sstream>
-#else
-# include <strstream>
-#endif
-
-#ifdef HAVE_SSTREAM
-  std::ostringstream oss;
-#else
-  std::ostrstream oss;
-#endif
-
-oss << "Name=" << m_name << ", number=" << m_number << std::endl;
-...
-#ifndef HAVE_SSTREAM
-  oss << std::ends; // terminate the char*-string
-#endif
-
-// str() returns char* for ostrstream and a string for ostringstream
-// this also causes ostrstream to think that the buffer's memory
-// is yours
-m_label.set_text(oss.str());
-#ifndef HAVE_SSTREAM
-  // let the ostrstream take care of freeing the memory
-  oss.freeze(false);
-#endif
-

- Input-stringstreams can be used similarly: -

-std::string input;
-...
-#ifdef HAVE_SSTREAM
-std::istringstream iss(input);
-#else
-std::istrstream iss(input.c_str());
-#endif
-
-int i;
-iss >> i;
-

One (the only?) restriction is that an istrstream cannot be re-filled: -

-std::istringstream iss(numerator);
-iss >> m_num;
-// this is not possible with istrstream
-iss.clear();
-iss.str(denominator);
-iss >> m_den;
-

-If you don't care about speed, you can put these conversions in - a template-function: -

-template <class X>
-void fromString(const string& input, X& any)
-{
-#ifdef HAVE_SSTREAM
-std::istringstream iss(input);
-#else
-std::istrstream iss(input.c_str());
-#endif
-X temp;
-iss >> temp;
-if (iss.fail())
-throw runtime_error(..)
-any = temp;
-}
-

- Another example of using stringstreams is in this howto. -

There is additional information in the libstdc++-v2 info files, in -particular “info iostream”. -

Little or no wide character support

- Classes wstring and - char_traits<wchar_t> are - not supported. -

No templatized iostreams

- Classes wfilebuf and - wstringstream are not supported. -

Thread safety issues

- Earlier GCC releases had a somewhat different approach to - threading configuration and proper compilation. Before GCC 3.0, - configuration of the threading model was dictated by compiler - command-line options and macros (both of which were somewhat - thread-implementation and port-specific). There were no - guarantees related to being able to link code compiled with one - set of options and macro setting with another set. -

- For GCC 3.0, configuration of the threading model used with - libraries and user-code is performed when GCC is configured and - built using the --enable-threads and --disable-threads options. - The ABI is stable for symbol name-mangling and limited functional - compatibility exists between code compiled under different - threading models. -

- The libstdc++ library has been designed so that it can be used in - multithreaded applications (with libstdc++-v2 this was only true - of the STL parts.) The first problem is finding a - fast method of implementation portable to - all platforms. Due to historical reasons, some of the library is - written against per-CPU-architecture spinlocks and other parts - against the gthr.h abstraction layer which is provided by gcc. A - minor problem that pops up every so often is different - interpretations of what "thread-safe" means for a - library (not a general program). We currently use the same - definition that SGI uses for their STL subset. However, - the exception for read-only containers only applies to the STL - components. This definition is widely-used and something similar - will be used in the next version of the C++ standard library. -

- Here is a small link farm to threads (no pun) in the mail - archives that discuss the threading problem. Each link is to the - first relevant message in the thread; from there you can use - "Thread Next" to move down the thread. This farm is in - latest-to-oldest order. -

  • - Our threading expert Loren gives a breakdown of the - six situations involving threads for the 3.0 - release series. -

  • - - This message inspired a recent updating of issues with - threading and the SGI STL library. It also contains some - example POSIX-multithreaded STL code. -

- (A large selection of links to older messages has been removed; - many of the messages from 1999 were lost in a disk crash, and the - few people with access to the backup tapes have been too swamped - with work to restore them. Many of the points have been - superseded anyhow.) -

Third

The third generation GNU C++ library is called libstdc++, or + That project is no longer maintained or supported, and the sources + archived. The code was replaced and rewritten for libstdc++-v3. +

Third

The third generation GNU C++ library is called libstdc++, or libstdc++-v3.

The subset commonly known as the Standard Template Library - (clauses 23 through 25, mostly) is adapted from the final release + (clauses 23 through 25 in C++98, mostly) is adapted from the final release of the SGI STL (version 3.3), with extensive changes.

A more formal description of the V3 goals can be found in the official design document. @@ -888,19 +561,7 @@ AC_DEFUN([AC_HEADER_UNORDERED_SET], [ This is a change in behavior from older versions. Now, most iterator_type typedefs in container classes are POD objects, not value_type pointers. -

Bibliography

- - Migrating to GCC 4.1 - - . Dan Kegel.

- - Building the Whole Debian Archive with GCC 4.1: A Summary - - . Martin Michlmayr.

- - Migration guide for GCC-3.2 - - .

Prev Up Next
API Evolution and Deprecation History Home Appendix C.  +

Prev Up Next
API Evolution and Deprecation History Home Appendix C.  Free Software Needs Free Documentation
\ No newline at end of file diff --git a/libstdc++-v3/doc/html/manual/index.html b/libstdc++-v3/doc/html/manual/index.html index 24a4ba97baf4..e34210ee5d98 100644 --- a/libstdc++-v3/doc/html/manual/index.html +++ b/libstdc++-v3/doc/html/manual/index.html @@ -123,11 +123,7 @@ Existing tests
C++11 Requirements Test Sequence Descriptions -
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
No ios_base
No cout in <ostream.h>, no cin in <istream.h>
Second
Namespace std:: not supported
Illegal iterator usage
isspace from <cctype> is a macro -
No vector::at, deque::at, string::at
No std::char_traits<char>::eof
No string::clear
- Removal of ostream::form and istream::scan - extensions -
No basic_stringbuf, basic_stringstream
Little or no wide character support
No templatized iostreams
Thread safety issues
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace. +
ABI Policy and Guidelines
The C++ Interface
Versioning
Goals
History
Prerequisites
Configuring
Checking Active
Allowed Changes
Prohibited Changes
Implementation
Testing
Single ABI Testing
Multiple ABI Testing
Outstanding Issues
API Evolution and Deprecation History
3.0
3.1
3.2
3.3
3.4
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
5.3
6
7
7.2
7.3
8
9
10
11
Backwards Compatibility
First
Second
Third
Pre-ISO headers removed
Extension headers hash_map, hash_set moved to ext or backwards
No ios::nocreate/ios::noreplace.
No stream::attach(int fd)
diff --git a/libstdc++-v3/doc/xml/manual/backwards_compatibility.xml b/libstdc++-v3/doc/xml/manual/backwards_compatibility.xml index cce553380e11..6a4a5ccedfbf 100644 --- a/libstdc++-v3/doc/xml/manual/backwards_compatibility.xml +++ b/libstdc++-v3/doc/xml/manual/backwards_compatibility.xml @@ -22,7 +22,7 @@ dinosaur. Some background: libg++ was designed and created when there was no ISO standard to provide guidance. Classes like linked lists are now -provided for by list<T> and do not need to be +provided for by std::list<T> and do not need to be created by genclass. (For that matter, templates exist now and are well-supported, whereas genclass (mostly) predates them.) @@ -34,41 +34,13 @@ Committee couldn't include everything, and so a lot of those obvious classes didn't get included. -Known Issues include many of the limitations of its immediate ancestor. - -Portability notes and known implementation limitations are as follows. - -
No <code>ios_base</code> - - - At least some older implementations don't have std::ios_base, so you should use std::ios::badbit, std::ios::failbit and std::ios::eofbit and std::ios::goodbit. +That project is no longer maintained or supported, and the sources +archived. For the desperate, the +ftp.gnu.org +server still has the libg++ source.
-
No <code>cout</code> in <filename class="headerfile"><ostream.h></filename>, no <code>cin</code> in <filename class="headerfile"><istream.h></filename> - - - - In earlier versions of the standard, - <fstream.h>, - <ostream.h> - and <istream.h> - used to define - cout, cin and so on. ISO C++ specifies that one needs to include - <iostream> - explicitly to get the required definitions. - - Some include adjustment may be required. - -This project is no longer maintained or supported, and the sources -archived. For the desperate, -the GCC extensions -page describes where to find the last libg++ source. The code is -considered replaced and rewritten. - -
- -
Second @@ -80,503 +52,13 @@ considered replaced and rewritten. - The STL portions of this library are based on SGI/HP STL release 3.11. - - - - This project is no longer maintained or supported, and the sources - archived. The code is considered replaced and rewritten. - - - - Portability notes and known implementation limitations are as follows. - - -
Namespace <code>std::</code> not supported - - - - Some care is required to support C++ compiler and or library - implementation that do not have the standard library in - namespace std. - - - - The following sections list some possible solutions to support compilers - that cannot ignore std::-qualified names. - - - - First, see if the compiler has a flag for this. Namespace - back-portability-issues are generally not a problem for g++ - compilers that do not have libstdc++ in std::, as the - compilers use (ignore - std::, :: = std::) by default. That is, - the responsibility for enabling or disabling std:: is - on the user; the maintainer does not have to care about it. This - probably applies to some other compilers as well. - - - - Second, experiment with a variety of pre-processor tricks. - - - - By defining std as a macro, fully-qualified namespace - calls become global. Volia. - - - -#ifdef WICKEDLY_OLD_COMPILER -# define std -#endif - - - - Thanks to Juergen Heinzl who posted this solution on gnu.gcc.help. - - - - Another pre-processor based approach is to define a macro - NAMESPACE_STD, which is defined to either - or std based on a compile-type - test. On GNU systems, this can be done with autotools by means of - an autoconf test (see below) for HAVE_NAMESPACE_STD, - then using that to set a value for the NAMESPACE_STD - macro. At that point, one is able to use - NAMESPACE_STD::string, which will evaluate to - std::string or ::string (i.e., in the - global namespace on systems that do not put string in - std::). - - - -dnl @synopsis AC_CXX_NAMESPACE_STD -dnl -dnl If the compiler supports namespace std, define -dnl HAVE_NAMESPACE_STD. -dnl -dnl @category Cxx -dnl @author Todd Veldhuizen -dnl @author Luc Maisonobe <luc@spaceroots.org> -dnl @version 2004-02-04 -dnl @license AllPermissive -AC_DEFUN([AC_CXX_NAMESPACE_STD], [ - AC_CACHE_CHECK(if g++ supports namespace std, - ac_cv_cxx_have_std_namespace, - [AC_LANG_SAVE - AC_LANG_CPLUSPLUS - AC_TRY_COMPILE([#include <iostream> - std::istream& is = std::cin;],, - ac_cv_cxx_have_std_namespace=yes, ac_cv_cxx_have_std_namespace=no) - AC_LANG_RESTORE - ]) - if test "$ac_cv_cxx_have_std_namespace" = yes; then - AC_DEFINE(HAVE_NAMESPACE_STD,,[Define if g++ supports namespace std. ]) - fi -]) - -
- -
Illegal iterator usage - - - The following illustrate implementation-allowed illegal iterator - use, and then correct use. - - - - - - you cannot do ostream::operator<<(iterator) - to print the address of the iterator => use - operator<< &*iterator instead - - - - - you cannot clear an iterator's reference (iterator = - 0) => use iterator = iterator_type(); - - - - - if (iterator) won't work any more => use - if (iterator != iterator_type()) - - - -
- -
<code>isspace</code> from <filename class="headerfile"><cctype></filename> is a macro - - - - - Glibc 2.0.x and 2.1.x define <ctype.h> functionality as macros - (isspace, isalpha etc.). - - - - This implementations of libstdc++, however, keep these functions - as macros, and so it is not back-portable to use fully qualified - names. For example: - - - -#include <cctype> -int main() { std::isspace('X'); } - - - - Results in something like this: - - - -std:: (__ctype_b[(int) ( ( 'X' ) )] & (unsigned short int) _ISspace ) ; - - - - A solution is to modify a header-file so that the compiler tells - <ctype.h> to define functions - instead of macros: - - - -// This keeps isalnum, et al from being propagated as macros. -#if __linux__ -# define __NO_CTYPE 1 -#endif - - - - Then, include <ctype.h> - - - - Another problem arises if you put a using namespace - std; declaration at the top, and include - <ctype.h>. This will - result in ambiguities between the definitions in the global namespace - (<ctype.h>) and the - definitions in namespace std:: - (<cctype>). - -
- -
No <code>vector::at</code>, <code>deque::at</code>, <code>string::at</code> - - - - One solution is to add an autoconf-test for this: - - - -AC_MSG_CHECKING(for container::at) -AC_TRY_COMPILE( -[ -#include <vector> -#include <deque> -#include <string> - -using namespace std; -], -[ -deque<int> test_deque(3); -test_deque.at(2); -vector<int> test_vector(2); -test_vector.at(1); -string test_string(test_string); -test_string.at(3); -], -[AC_MSG_RESULT(yes) -AC_DEFINE(HAVE_CONTAINER_AT)], -[AC_MSG_RESULT(no)]) - - - - If you are using other (non-GNU) compilers it might be a good idea - to check for string::at separately. - - -
- -
No <code>std::char_traits<char>::eof</code> - - - - Use some kind of autoconf test, plus this: - - - -#ifdef HAVE_CHAR_TRAITS -#define CPP_EOF std::char_traits<char>::eof() -#else -#define CPP_EOF EOF -#endif - - -
- -
No <code>string::clear</code> - - - - There are two functions for deleting the contents of a string: - clear and erase (the latter returns the - string). - - - -void -clear() { _M_mutate(0, this->size(), 0); } - - - -basic_string& -erase(size_type __pos = 0, size_type __n = npos) -{ - return this->replace(_M_check(__pos), _M_fold(__pos, __n), - _M_data(), _M_data()); -} - - - - Unfortunately, clear is not implemented in this - version, so you should use erase (which is probably - faster than operator=(charT*)). - -
- -
- Removal of <code>ostream::form</code> and <code>istream::scan</code> - extensions - - - - - These are no longer supported. Please use stringstreams instead. - -
- -
No <code>basic_stringbuf</code>, <code>basic_stringstream</code> - - - - Although the ISO standard i/ostringstream-classes are - provided, (<sstream>), for - compatibility with older implementations the pre-ISO - i/ostrstream (<strstream>) interface is also provided, - with these caveats: - - - - - - strstream is considered to be deprecated - - - - - strstream is limited to char - - - - - with ostringstream you don't have to take care of - terminating the string or freeing its memory - - - - - istringstream can be re-filled (clear(); - str(input);) - - - - - - You can then use output-stringstreams like this: - - - -#ifdef HAVE_SSTREAM -# include <sstream> -#else -# include <strstream> -#endif - -#ifdef HAVE_SSTREAM - std::ostringstream oss; -#else - std::ostrstream oss; -#endif - -oss << "Name=" << m_name << ", number=" << m_number << std::endl; -... -#ifndef HAVE_SSTREAM - oss << std::ends; // terminate the char*-string -#endif - -// str() returns char* for ostrstream and a string for ostringstream -// this also causes ostrstream to think that the buffer's memory -// is yours -m_label.set_text(oss.str()); -#ifndef HAVE_SSTREAM - // let the ostrstream take care of freeing the memory - oss.freeze(false); -#endif - - - - Input-stringstreams can be used similarly: - - - -std::string input; -... -#ifdef HAVE_SSTREAM -std::istringstream iss(input); -#else -std::istrstream iss(input.c_str()); -#endif - -int i; -iss >> i; - - - One (the only?) restriction is that an istrstream cannot be re-filled: - - - -std::istringstream iss(numerator); -iss >> m_num; -// this is not possible with istrstream -iss.clear(); -iss.str(denominator); -iss >> m_den; - - - -If you don't care about speed, you can put these conversions in - a template-function: + The STL portions of that library are based on SGI/HP STL release 3.11. - -template <class X> -void fromString(const string& input, X& any) -{ -#ifdef HAVE_SSTREAM -std::istringstream iss(input); -#else -std::istrstream iss(input.c_str()); -#endif -X temp; -iss >> temp; -if (iss.fail()) -throw runtime_error(..) -any = temp; -} - - Another example of using stringstreams is in this howto. - - - There is additional information in the libstdc++-v2 info files, in -particular info iostream. + That project is no longer maintained or supported, and the sources + archived. The code was replaced and rewritten for libstdc++-v3. -
- -
Little or no wide character support - - - Classes wstring and - char_traits<wchar_t> are - not supported. - -
- -
No templatized iostreams - - - Classes wfilebuf and - wstringstream are not supported. - -
- -
Thread safety issues - - - - Earlier GCC releases had a somewhat different approach to - threading configuration and proper compilation. Before GCC 3.0, - configuration of the threading model was dictated by compiler - command-line options and macros (both of which were somewhat - thread-implementation and port-specific). There were no - guarantees related to being able to link code compiled with one - set of options and macro setting with another set. - - - - For GCC 3.0, configuration of the threading model used with - libraries and user-code is performed when GCC is configured and - built using the --enable-threads and --disable-threads options. - The ABI is stable for symbol name-mangling and limited functional - compatibility exists between code compiled under different - threading models. - - - - The libstdc++ library has been designed so that it can be used in - multithreaded applications (with libstdc++-v2 this was only true - of the STL parts.) The first problem is finding a - fast method of implementation portable to - all platforms. Due to historical reasons, some of the library is - written against per-CPU-architecture spinlocks and other parts - against the gthr.h abstraction layer which is provided by gcc. A - minor problem that pops up every so often is different - interpretations of what "thread-safe" means for a - library (not a general program). We currently use the same - definition that SGI uses for their STL subset. However, - the exception for read-only containers only applies to the STL - components. This definition is widely-used and something similar - will be used in the next version of the C++ standard library. - - - - Here is a small link farm to threads (no pun) in the mail - archives that discuss the threading problem. Each link is to the - first relevant message in the thread; from there you can use - "Thread Next" to move down the thread. This farm is in - latest-to-oldest order. - - - - - - Our threading expert Loren gives a breakdown of the - six situations involving threads for the 3.0 - release series. - - - - - - This message inspired a recent updating of issues with - threading and the SGI STL library. It also contains some - example POSIX-multithreaded STL code. - - - - - - (A large selection of links to older messages has been removed; - many of the messages from 1999 were lost in a disk crash, and the - few people with access to the backup tapes have been too swamped - with work to restore them. Many of the points have been - superseded anyhow.) - -
@@ -588,7 +70,7 @@ libstdc++-v3. The subset commonly known as the Standard Template Library - (clauses 23 through 25, mostly) is adapted from the final release + (clauses 23 through 25 in C++98, mostly) is adapted from the final release of the SGI STL (version 3.3), with extensive changes. @@ -1223,40 +705,4 @@ AC_DEFUN([AC_HEADER_UNORDERED_SET], [ -Bibliography - - - - - <link xmlns:xlink="http://www.w3.org/1999/xlink" - xlink:href="http://www.kegel.com/gcc/gcc4.html"> - Migrating to GCC 4.1 - </link> - - - DanKegel - - - - - <link xmlns:xlink="http://www.w3.org/1999/xlink" - xlink:href="https://lists.debian.org/debian-gcc/2006/03/msg00405.html"> - Building the Whole Debian Archive with GCC 4.1: A Summary - </link> - - MartinMichlmayr - - - - - <link xmlns:xlink="http://www.w3.org/1999/xlink" - xlink:href="http://annwm.lbl.gov/~leggett/Atlas/gcc-3.2.html"> - Migration guide for GCC-3.2 - </link> - - - - - -