ISO C++ library

There are two licenses affecting GNU libstdc++: one for the code, and one for the documentation. There is a license section in the FAQ regarding common questions. If you have more questions, ask the FSF or the gcc mailing list.

The source code is distributed under the GNU General Public License version 3, with the addition under section 7 of an exception described in the GCC Runtime Library Exception, version 3.1 as follows (or see the file COPYING.RUNTIME): GCC RUNTIME LIBRARY EXCEPTION Version 3.1, 31 March 2009 Copyright (C) 2009 Free Software Foundation, Inc. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. This GCC Runtime Library Exception ("Exception") is an additional permission under section 7 of the GNU General Public License, version 3 ("GPLv3"). It applies to a given file (the "Runtime Library") that bears a notice placed by the copyright holder of the file stating that the file is governed by GPLv3 along with this Exception. When you use GCC to compile a program, GCC may combine portions of certain GCC header files and runtime libraries with the compiled program. The purpose of this Exception is to allow compilation of non-GPL (including proprietary) programs to use, in this way, the header files and runtime libraries covered by this Exception. 0. Definitions. A file is an "Independent Module" if it either requires the Runtime Library for execution after a Compilation Process, or makes use of an interface provided by the Runtime Library, but is not otherwise based on the Runtime Library. "GCC" means a version of the GNU Compiler Collection, with or without modifications, governed by version 3 (or a specified later version) of the GNU General Public License (GPL) with the option of using any subsequent versions published by the FSF. "GPL-compatible Software" is software whose conditions of propagation, modification and use would permit combination with GCC in accord with the license of GCC. "Target Code" refers to output from any compiler for a real or virtual target processor architecture, in executable form or suitable for input to an assembler, loader, linker and/or execution phase. Notwithstanding that, Target Code does not include data in any format that is used as a compiler intermediate representation, or used for producing a compiler intermediate representation. The "Compilation Process" transforms code entirely represented in non-intermediate languages designed for human-written code, and/or in Java Virtual Machine byte code, into Target Code. Thus, for example, use of source code generators and preprocessors need not be considered part of the Compilation Process, since the Compilation Process can be understood as starting with the output of the generators or preprocessors. A Compilation Process is "Eligible" if it is done using GCC, alone or with other GPL-compatible software, or if it is done without using any work based on GCC. For example, using non-GPL-compatible Software to optimize any GCC intermediate representations would not qualify as an Eligible Compilation Process. 1. Grant of Additional Permission. You have permission to propagate a work of Target Code formed by combining the Runtime Library with Independent Modules, even if such propagation would otherwise violate the terms of GPLv3, provided that all Target Code was generated by Eligible Compilation Processes. You may then convey such a combination under terms of your choice, consistent with the licensing of the Independent Modules. 2. No Weakening of GCC Copyleft. The availability of this Exception does not imply any general presumption that third-party software is unaffected by the copyleft requirements of the license of GCC. Hopefully that text is self-explanatory. If it isn't, you need to speak to your lawyer, or the Free Software Foundation.

The documentation shipped with the library and made available over the web, excluding the pages generated from source comments, are copyrighted by the Free Software Foundation, and placed under the GNU Free Documentation License version 1.3. There are no Front-Cover Texts, no Back-Cover Texts, and no Invariant Sections. For documentation generated by doxygen or other automated tools via processing source code comments and markup, the original source code license applies to the generated files. Thus, the doxygen documents are licensed GPL. If you plan on making copies of the documentation, please let us know. We can probably offer suggestions.

Information on known bugs, details on efforts to fix them, and fixed bugs are all available as part of the GCC bug tracking system, with the category set to libstdc++.

Everybody's got issues. Even the C++ Standard Library. The Library Working Group, or LWG, is the ISO subcommittee responsible for making changes to the library. They periodically publish an Issues List containing problems and possible solutions. As they reach a consensus on proposed solutions, we often incorporate the solution. Here are the issues which have resulted in code changes to the library. The links are to the specific defect reports from a partial copy of the Issues List. You can read the full version online at the ISO C++ Committee homepage, linked to on the GCC "Readings" page. If you spend a lot of time reading the issues, we recommend downloading the ZIP file and reading them locally. (NB: partial copy means that not all links within the lwg-*.html pages will work. Specifically, links to defect reports that have not been accorded full DR status will probably break. Rather than trying to mirror the entire issues list on our overworked web server, we recommend you go to the LWG homepage instead.) If a DR is not listed here, we may simply not have gotten to it yet; feel free to submit a patch. Search the include/bits and src directories for appearances of _GLIBCXX_RESOLVE_LIB_DEFECTS for examples of style. Note that we usually do not make changes to the code until an issue has reached DR status. 5: string::compare specification questionable This should be two overloaded functions rather than a single function. 17: Bad bool parsing Apparently extracting Boolean values was messed up... 19: "Noconv" definition too vague If codecvt::do_in returns noconv there are no changes to the values in [to, to_limit). 22: Member open vs flags Re-opening a file stream does not clear the state flags. 23: Num_get overflow result Implement the proposed resolution. 25: String operator<< uses width() value wrong Padding issues. 48: Use of non-existent exception constructor An instance of ios_base::failure is constructed instead. 49: Underspecification of ios_base::sync_with_stdio The return type is the previous state of synchronization. 50: Copy constructor and assignment operator of ios_base These members functions are declared private and are thus inaccessible. Specifying the correct semantics of "copying stream state" was deemed too complicated. 60: What is a formatted input function? This DR made many widespread changes to basic_istream and basic_ostream all of which have been implemented. 63: Exception-handling policy for unformatted output Make the policy consistent with that of formatted input, unformatted input, and formatted output. 68: Extractors for char* should store null at end And they do now. An editing glitch in the last item in the list of [27.6.1.2.3]/7. 74: Garbled text for codecvt::do_max_length The text of the standard was gibberish. Typos gone rampant. 75: Contradiction in codecvt::length's argument types Change the first parameter to stateT& and implement the new effects paragraph. 83: string::npos vs. string::max_size() Safety checks on the size of the string should test against max_size() rather than npos. 90: Incorrect description of operator>> for strings The effect contain isspace(c,getloc()) which must be replaced by isspace(c,is.getloc()). 91: Description of operator>> and getline() for string<> might cause endless loop They behave as a formatted input function and as an unformatted input function, respectively (except that getline is not required to set gcount). 103: set::iterator is required to be modifiable, but this allows modification of keys. For associative containers where the value type is the same as the key type, both iterator and const_iterator are constant iterators. 109: Missing binders for non-const sequence elements The binder1st and binder2nd didn't have an operator() taking a non-const parameter. 110: istreambuf_iterator::equal not const This was not a const member function. Note that the DR says to replace the function with a const one; we have instead provided an overloaded version with identical contents. 117: basic_ostream uses nonexistent num_put member functions num_put::put() was overloaded on the wrong types. 118: basic_istream uses nonexistent num_get member functions Same as 117, but for num_get::get(). 129: Need error indication from seekp() and seekg() These functions set failbit on error now. 130: Return type of container::erase(iterator) differs for associative containers Make member erase return iterator for set, multiset, map, multimap. 136: seekp, seekg setting wrong streams? seekp should only set the output stream, and seekg should only set the input stream. 167: Improper use of traits_type::length() op<< with a const char* was calculating an incorrect number of characters to write. 169: Bad efficiency of overflow() mandated Grow efficiently the internal array object. 171: Strange seekpos() semantics due to joint position Quite complex to summarize... 181: make_pair() unintended behavior This function used to take its arguments as reference-to-const, now it copies them (pass by value). 195: Should basic_istream::sentry's constructor ever set eofbit? Yes, it can, specifically if EOF is reached while skipping whitespace. 211: operator>>(istream&, string&) doesn't set failbit If nothing is extracted into the string, op>> now sets failbit (which can cause an exception, etc., etc.). 214: set::find() missing const overload Both set and multiset were missing overloaded find, lower_bound, upper_bound, and equal_range functions for const instances. 231: Precision in iostream? For conversion from a floating-point type, str.precision() is specified in the conversion specification. 233: Insertion hints in associative containers Implement N1780, first check before then check after, insert as close to hint as possible. 235: No specification of default ctor for reverse_iterator The declaration of reverse_iterator lists a default constructor. However, no specification is given what this constructor should do. 241: Does unique_copy() require CopyConstructible and Assignable? Add a helper for forward_iterator/output_iterator, fix the existing one for input_iterator/output_iterator to not rely on Assignability. 243: get and getline when sentry reports failure Store a null character only if the character array has a non-zero size. 251: basic_stringbuf missing allocator_type This nested typedef was originally not specified. 253: valarray helper functions are almost entirely useless Make the copy constructor and copy-assignment operator declarations public in gslice_array, indirect_array, mask_array, slice_array; provide definitions. 265: std::pair::pair() effects overly restrictive The default ctor would build its members from copies of temporaries; now it simply uses their respective default ctors. 266: bad_exception::~bad_exception() missing Effects clause The bad_* classes no longer have destructors (they are trivial), since no description of them was ever given. 271: basic_iostream missing typedefs The typedefs it inherits from its base classes can't be used, since (for example) basic_iostream<T>::traits_type is ambiguous. 275: Wrong type in num_get::get() overloads Similar to 118. 280: Comparison of reverse_iterator to const reverse_iterator Add global functions with two template parameters. (NB: not added for now a templated assignment operator) 292: Effects of a.copyfmt (a) If (this == &rhs) do nothing. 300: List::merge() specification incomplete If (this == &x) do nothing. 303: Bitset input operator underspecified Basically, compare the input character to is.widen(0) and is.widen(1). 305: Default behavior of codecvt<wchar_t, char, mbstate_t>::length() Do not specify what codecvt<wchar_t, char, mbstate_t>::do_length must return. 328: Bad sprintf format modifier in money_put<>::do_put() Change the format string to "%.0Lf". 365: Lack of const-qualification in clause 27 Add const overloads of is_open. 387: std::complex over-encapsulated Add the real(T) and imag(T) members; in C++11 mode, also adjust the existing real() and imag() members and free functions. 389: Const overload of valarray::operator[] returns by value Change it to return a const T&. 396: what are characters zero and one Implement the proposed resolution. 402: Wrong new expression in [some_]allocator::construct Replace "new" with "::new". 408: Is vector<reverse_iterator<char*> > forbidden? Tweak the debug-mode checks in _Safe_iterator. 409: Closing an fstream should clear the error state Have open clear the error flags. 431: Swapping containers with unequal allocators Implement Option 3, as per N1599. 432: stringbuf::overflow() makes only one write position available Implement the resolution, beyond DR 169. 434: bitset::to_string() hard to use Add three overloads, taking fewer template arguments. 438: Ambiguity in the "do the right thing" clause Implement the resolution, basically cast less. 453: basic_stringbuf::seekoff need not always fail for an empty stream Don't fail if the next pointer is null and newoff is zero. 455: cerr::tie() and wcerr::tie() are overspecified Initialize cerr tied to cout and wcerr tied to wcout. 464: Suggestion for new member functions in standard containers Add data() to std::vector and at(const key_type&) to std::map. 508: Bad parameters for ranlux64_base_01 Fix the parameters. 512: Seeding subtract_with_carry_01 from a single unsigned long Construct a linear_congruential engine and seed with it. 526: Is it undefined if a function in the standard changes in parameters? Use &value. 538: 241 again: Does unique_copy() require CopyConstructible and Assignable? In case of input_iterator/output_iterator rely on Assignability of input_iterator' value_type. 539: partial_sum and adjacent_difference should mention requirements We were almost doing the right thing, just use std::move in adjacent_difference. 541: shared_ptr template assignment and void Add an auto_ptr<void> specialization. 543: valarray slice default constructor Follow the straightforward proposed resolution. 550: What should the return type of pow(float,int) be? In C++11 mode, remove the pow(float,int), etc., signatures. 586: string inserter not a formatted function Change it to be a formatted output function (i.e. catch exceptions). 596: 27.8.1.3 Table 112 omits "a+" and "a+b" modes Add the missing modes to fopen_mode. 630: arrays of valarray Implement the simple resolution. 660: Missing bitwise operations Add the missing operations. 691: const_local_iterator cbegin, cend missing from TR1 In C++11 mode add cbegin(size_type) and cend(size_type) to the unordered containers. 693: std::bitset::all() missing Add it, consistently with the discussion. 695: ctype<char>::classic_table() not accessible Make the member functions table and classic_table public. 696: istream::operator>>(int&) broken Implement the straightforward resolution. 761: unordered_map needs an at() member function In C++11 mode, add at() and at() const. 775: Tuple indexing should be unsigned? Implement the int -> size_t replacements. 776: Undescribed assign function of std::array In C++11 mode, remove assign, add fill. 781: std::complex should add missing C99 functions In C++11 mode, add std::proj. 809: std::swap should be overloaded for array types Add the overload. 853: to_string needs updating with zero and one Update / add the signatures. 865: More algorithms that throw away information The traditional HP / SGI return type and value is blessed by the resolution of the DR.

To transform libstdc++ sources into installed include files and properly built binaries useful for linking to other software is a multi-step process. Steps include getting the sources, configuring and building the sources, testing, and installation. The general outline of commands is something like: get gcc sources extract into gccsrcdir mkdir gccbuilddir cd gccbuilddir gccsrcdir/configure --prefix=destdir --other-opts... make make check make install Each step is described in more detail in the following sections.

If you have never done this before, you should read the basic GCC Installation Instructions first. Read all of them. Twice. Then type: make, and congratulations, you've started to build.