My recent r15-9381-g648d5c26e25497 change assumes that a contiguous iterator with the correct value_type can be converted to a const charT* but that's not true for volatile charT*. The optimization should only be done if it can be converted to the right pointer type. Additionally, some generic loops for non-contiguous iterators need an explicit cast to deal with iterator reference types that do not bind to the const charT& parameter of traits_type::assign. libstdc++-v3/ChangeLog: PR libstdc++/119748 * include/bits/basic_string.h (_S_copy_chars): Only optimize for contiguous iterators that are convertible to const charT*. Use explicit conversion to charT after dereferencing iterator. (_S_copy_range): Likewise for contiguous ranges. * include/bits/basic_string.tcc (_M_construct): Use explicit conversion to charT after dereferencing iterator. * include/bits/cow_string.h (_S_copy_chars): Likewise. (basic_string(from_range_t, R&&, const Allocator&)): Likewise. Only optimize for contiguous iterators that are convertible to const charT*. * testsuite/21_strings/basic_string/cons/char/119748.cc: New test. * testsuite/21_strings/basic_string/cons/wchar_t/119748.cc: New test. Reviewed-by: Tomasz Kaminski <tkaminsk@redhat.com>
libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc: Fix whitespace.
this patch improves code generation on string constructors. We currently have _M_construct which takes as a parameter two iterators (begin/end pointers to other string) and produces new string. This patch adds special case of constructor where instead of begining/end pointers we readily know the string size and also special case when we know that source is 0 terminated. This happens commonly when producing stirng copies. Moreover currently ipa-prop is not able to propagate information that beg-end is known constant (copied string size) which makes it impossible for inliner to spot the common case where string size is known to be shorter than 15 bytes and fits in local buffer. Finally I made new constructor inline. Because it is explicitely instantiated without C++20 constexpr we do not produce implicit instantiation (as required by standard) which prevents inlining, ipa-modref and any other IPA analysis to happen. I think we need to make many of the other functions inline, since optimization accross string manipulation is quite important. There is PR94960 to track this issue. Bootstrapped/regtested x86_64-linux, OK? libstdc++-v3/ChangeLog: PR tree-optimization/103827 PR tree-optimization/80331 PR tree-optimization/87502 * config/abi/pre/gnu.ver: Add version for _M_construct<bool> * include/bits/basic_string.h: (basic_string::_M_construct<bool>): Declare. (basic_string constructors): Use it. * include/bits/basic_string.tcc: (basic_string::_M_construct<bool>): New template. * src/c++11/string-inst.cc: Instantated S::_M_construct<bool>. gcc/testsuite/ChangeLog: * g++.dg/tree-ssa/pr80331.C: New test. * g++.dg/tree-ssa/pr87502.C: New test.
libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc (resize_for_overwrite): Fix -Wsign-compare warning. * include/bits/cow_string.h (resize_for_overwrite): Likewise.
In r15-3714-gd3a7302ec5985a I added -Wsystem-headers to the libstdc++ build flags to help catch problems in the library. This patch takes a different approach, of disabling the #pragma system_header unless _GLIBCXX_SYSHDR is defined. As a result, the testsuites will treat them as non-system-headers to get better warning coverage during regression testing of both gcc and libstdc++, not just when building the library. My rationale for the #ifdef instead of just removing the #pragma is the three G++ tests that want to test libstdc++ system header behavior, so we need a way to select it. This doesn't affect installed libraries, as they get their system-header status from the lookup path. But testsuite_flags --build-includes gives -I directives rather than -isystem. This patch doesn't change the headers in config/ because I'm not compiling with most of them, so won't see any warnings that need fixing. Adjusting them could happen later, or we can not bother. libstdc++-v3/ChangeLog: * acinclude.m4 (WARN_FLAGS): Remove -Wsystem-headers. * configure: Regenerate. * include/bits/algorithmfwd.h: #ifdef out #pragma GCC system_header. * include/bits/atomic_base.h * include/bits/atomic_futex.h * include/bits/atomic_timed_wait.h * include/bits/atomic_wait.h * include/bits/basic_ios.h * include/bits/basic_string.h * include/bits/boost_concept_check.h * include/bits/char_traits.h * include/bits/charconv.h * include/bits/chrono.h * include/bits/chrono_io.h * include/bits/codecvt.h * include/bits/concept_check.h * include/bits/cpp_type_traits.h * include/bits/elements_of.h * include/bits/enable_special_members.h * include/bits/erase_if.h * include/bits/forward_list.h * include/bits/functional_hash.h * include/bits/gslice.h * include/bits/gslice_array.h * include/bits/hashtable.h * include/bits/indirect_array.h * include/bits/invoke.h * include/bits/ios_base.h * include/bits/iterator_concepts.h * include/bits/locale_classes.h * include/bits/locale_facets.h * include/bits/locale_facets_nonio.h * include/bits/localefwd.h * include/bits/mask_array.h * include/bits/max_size_type.h * include/bits/memory_resource.h * include/bits/memoryfwd.h * include/bits/move_only_function.h * include/bits/node_handle.h * include/bits/ostream_insert.h * include/bits/out_ptr.h * include/bits/parse_numbers.h * include/bits/postypes.h * include/bits/quoted_string.h * include/bits/range_access.h * include/bits/ranges_base.h * include/bits/refwrap.h * include/bits/sat_arith.h * include/bits/semaphore_base.h * include/bits/slice_array.h * include/bits/std_abs.h * include/bits/std_function.h * include/bits/std_mutex.h * include/bits/std_thread.h * include/bits/stl_iterator_base_funcs.h * include/bits/stl_iterator_base_types.h * include/bits/stl_tree.h * include/bits/stream_iterator.h * include/bits/streambuf_iterator.h * include/bits/stringfwd.h * include/bits/this_thread_sleep.h * include/bits/unique_lock.h * include/bits/uses_allocator_args.h * include/bits/utility.h * include/bits/valarray_after.h * include/bits/valarray_array.h * include/bits/valarray_before.h * include/bits/version.h * include/c_compatibility/fenv.h * include/c_compatibility/inttypes.h * include/c_compatibility/stdint.h * include/decimal/decimal.h * include/experimental/bits/net.h * include/experimental/bits/shared_ptr.h * include/ext/aligned_buffer.h * include/ext/alloc_traits.h * include/ext/atomicity.h * include/ext/concurrence.h * include/ext/numeric_traits.h * include/ext/pod_char_traits.h * include/ext/pointer.h * include/ext/stdio_filebuf.h * include/ext/stdio_sync_filebuf.h * include/ext/string_conversions.h * include/ext/type_traits.h * include/ext/vstring.h * include/ext/vstring_fwd.h * include/ext/vstring_util.h * include/parallel/algorithmfwd.h * include/parallel/numericfwd.h * include/tr1/functional_hash.h * include/tr1/hashtable.h * include/tr1/random.h * libsupc++/exception.h * libsupc++/hash_bytes.h * include/bits/basic_ios.tcc * include/bits/basic_string.tcc * include/bits/fstream.tcc * include/bits/istream.tcc * include/bits/locale_classes.tcc * include/bits/locale_facets.tcc * include/bits/locale_facets_nonio.tcc * include/bits/ostream.tcc * include/bits/sstream.tcc * include/bits/streambuf.tcc * include/bits/string_view.tcc * include/bits/version.tpl * include/experimental/bits/string_view.tcc * include/ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp * include/ext/random.tcc * include/ext/vstring.tcc * include/tr2/bool_set.tcc * include/tr2/dynamic_bitset.tcc * include/bits/c++config * include/c/cassert * include/c/cctype * include/c/cerrno * include/c/cfloat * include/c/ciso646 * include/c/climits * include/c/clocale * include/c/cmath * include/c/csetjmp * include/c/csignal * include/c/cstdarg * include/c/cstddef * include/c/cstdio * include/c/cstdlib * include/c/cstring * include/c/ctime * include/c/cuchar * include/c/cwchar * include/c/cwctype * include/c_global/cassert * include/c_global/ccomplex * include/c_global/cctype * include/c_global/cerrno * include/c_global/cfenv * include/c_global/cfloat * include/c_global/cinttypes * include/c_global/ciso646 * include/c_global/climits * include/c_global/clocale * include/c_global/cmath * include/c_global/csetjmp * include/c_global/csignal * include/c_global/cstdalign * include/c_global/cstdarg * include/c_global/cstdbool * include/c_global/cstddef * include/c_global/cstdint * include/c_global/cstdio * include/c_global/cstdlib * include/c_global/cstring * include/c_global/ctgmath * include/c_global/ctime * include/c_global/cuchar * include/c_global/cwchar * include/c_global/cwctype * include/c_std/cassert * include/c_std/cctype * include/c_std/cerrno * include/c_std/cfloat * include/c_std/ciso646 * include/c_std/climits * include/c_std/clocale * include/c_std/cmath * include/c_std/csetjmp * include/c_std/csignal * include/c_std/cstdarg * include/c_std/cstddef * include/c_std/cstdio * include/c_std/cstdlib * include/c_std/cstring * include/c_std/ctime * include/c_std/cuchar * include/c_std/cwchar * include/c_std/cwctype * include/debug/array * include/debug/bitset * include/debug/deque * include/debug/forward_list * include/debug/list * include/debug/map * include/debug/set * include/debug/string * include/debug/unordered_map * include/debug/unordered_set * include/debug/vector * include/decimal/decimal * include/experimental/algorithm * include/experimental/any * include/experimental/array * include/experimental/buffer * include/experimental/chrono * include/experimental/contract * include/experimental/deque * include/experimental/executor * include/experimental/filesystem * include/experimental/forward_list * include/experimental/functional * include/experimental/internet * include/experimental/io_context * include/experimental/iterator * include/experimental/list * include/experimental/map * include/experimental/memory * include/experimental/memory_resource * include/experimental/net * include/experimental/netfwd * include/experimental/numeric * include/experimental/propagate_const * include/experimental/ratio * include/experimental/regex * include/experimental/scope * include/experimental/set * include/experimental/socket * include/experimental/string * include/experimental/string_view * include/experimental/synchronized_value * include/experimental/system_error * include/experimental/timer * include/experimental/tuple * include/experimental/type_traits * include/experimental/unordered_map * include/experimental/unordered_set * include/experimental/vector * include/ext/algorithm * include/ext/cmath * include/ext/functional * include/ext/iterator * include/ext/memory * include/ext/numeric * include/ext/random * include/ext/rb_tree * include/ext/rope * include/parallel/algorithm * include/std/algorithm * include/std/any * include/std/array * include/std/atomic * include/std/barrier * include/std/bit * include/std/bitset * include/std/charconv * include/std/chrono * include/std/codecvt * include/std/complex * include/std/concepts * include/std/condition_variable * include/std/coroutine * include/std/deque * include/std/execution * include/std/expected * include/std/filesystem * include/std/format * include/std/forward_list * include/std/fstream * include/std/functional * include/std/future * include/std/generator * include/std/iomanip * include/std/ios * include/std/iosfwd * include/std/iostream * include/std/istream * include/std/iterator * include/std/latch * include/std/limits * include/std/list * include/std/locale * include/std/map * include/std/memory * include/std/memory_resource * include/std/mutex * include/std/numbers * include/std/numeric * include/std/optional * include/std/ostream * include/std/print * include/std/queue * include/std/random * include/std/ranges * include/std/ratio * include/std/regex * include/std/scoped_allocator * include/std/semaphore * include/std/set * include/std/shared_mutex * include/std/span * include/std/spanstream * include/std/sstream * include/std/stack * include/std/stacktrace * include/std/stdexcept * include/std/streambuf * include/std/string * include/std/string_view * include/std/syncstream * include/std/system_error * include/std/text_encoding * include/std/thread * include/std/tuple * include/std/type_traits * include/std/typeindex * include/std/unordered_map * include/std/unordered_set * include/std/utility * include/std/valarray * include/std/variant * include/std/vector * include/std/version * include/tr1/array * include/tr1/cfenv * include/tr1/cinttypes * include/tr1/cmath * include/tr1/complex * include/tr1/cstdbool * include/tr1/cstdint * include/tr1/cstdio * include/tr1/cstdlib * include/tr1/cwchar * include/tr1/cwctype * include/tr1/functional * include/tr1/memory * include/tr1/random * include/tr1/regex * include/tr1/tuple * include/tr1/type_traits * include/tr1/unordered_map * include/tr1/unordered_set * include/tr1/utility * include/tr2/bool_set * include/tr2/dynamic_bitset * include/tr2/type_traits * libsupc++/atomic_lockfree_defines.h * libsupc++/compare * libsupc++/cxxabi.h * libsupc++/cxxabi_forced.h * libsupc++/cxxabi_init_exception.h * libsupc++/exception * libsupc++/initializer_list * libsupc++/new * libsupc++/typeinfo: Likewise. * testsuite/20_util/ratio/operations/ops_overflow_neg.cc * testsuite/23_containers/array/tuple_interface/get_neg.cc * testsuite/23_containers/vector/cons/destructible_debug_neg.cc * testsuite/24_iterators/operations/prev_neg.cc * testsuite/ext/type_traits/add_unsigned_floating_neg.cc * testsuite/ext/type_traits/add_unsigned_integer_neg.cc * testsuite/ext/type_traits/remove_unsigned_floating_neg.cc * testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: Adjust line numbers. gcc/testsuite/ChangeLog * g++.dg/analyzer/fanalyzer-show-events-in-system-headers-default.C * g++.dg/analyzer/fanalyzer-show-events-in-system-headers-no.C * g++.dg/diagnostic/disable.C: #define _GLIBCXX_SYSHDR.
The use of #pragma GCC system_header in libstdc++ has led to bugs going undetected for a while due to the silencing of compiler warnings that would have revealed them promptly, and also interferes with warnings about problematic template instantiations induced by user code. But removing it, or even compiling with -Wsystem-header, is also problematic due to warnings about deliberate uses of extensions. So this patch adds #pragma GCC diagnostic as needed to suppress these warnings. The change to acinclude.m4 changes -Wabi to warn only in comparison to ABI 19, to avoid lots of warnings that we now mangle concept requirements, which are in any case still experimental. I checked for any other changes against ABI v15, and found only the <format> lambda mangling, which we can ignore. This also enables -Wsystem-headers while building the library, so we see any warnings not silenced by these #pragmas. libstdc++-v3/ChangeLog: * include/bits/algorithmfwd.h: * include/bits/allocator.h: * include/bits/codecvt.h: * include/bits/concept_check.h: * include/bits/cpp_type_traits.h: * include/bits/hashtable.h: * include/bits/iterator_concepts.h: * include/bits/ostream_insert.h: * include/bits/ranges_base.h: * include/bits/regex_automaton.h: * include/bits/std_abs.h: * include/bits/stl_algo.h: * include/c_compatibility/fenv.h: * include/c_compatibility/inttypes.h: * include/c_compatibility/stdint.h: * include/ext/concurrence.h: * include/ext/type_traits.h: * testsuite/ext/type_traits/add_unsigned_floating_neg.cc: * testsuite/ext/type_traits/add_unsigned_integer_neg.cc: * testsuite/ext/type_traits/remove_unsigned_floating_neg.cc: * testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: * include/bits/basic_ios.tcc: * include/bits/basic_string.tcc: * include/bits/fstream.tcc: * include/bits/istream.tcc: * include/bits/locale_classes.tcc: * include/bits/locale_facets.tcc: * include/bits/ostream.tcc: * include/bits/regex_compiler.tcc: * include/bits/sstream.tcc: * include/bits/streambuf.tcc: * configure: Regenerate. * include/bits/c++config: * include/c/cassert: * include/c/cctype: * include/c/cerrno: * include/c/cfloat: * include/c/climits: * include/c/clocale: * include/c/cmath: * include/c/csetjmp: * include/c/csignal: * include/c/cstdarg: * include/c/cstddef: * include/c/cstdio: * include/c/cstdlib: * include/c/cstring: * include/c/ctime: * include/c/cwchar: * include/c/cwctype: * include/c_global/climits: * include/c_global/cmath: * include/c_global/cstddef: * include/c_global/cstdlib: * include/decimal/decimal: * include/ext/rope: * include/std/any: * include/std/charconv: * include/std/complex: * include/std/coroutine: * include/std/format: * include/std/iomanip: * include/std/limits: * include/std/numbers: * include/tr1/functional: * include/tr1/tuple: * include/tr1/type_traits: * libsupc++/compare: * libsupc++/new: Add #pragma GCC diagnostic to suppress undesired warnings. * acinclude.m4: Change -Wabi version from 2 to 19. gcc/ChangeLog: * ginclude/stdint-wrap.h: Add #pragma GCC diagnostic to suppress undesired warnings. * gsyslimits.h: Likewise.
This change moves the definitions of feature test macros (or strictly speaking, the requests for <bits/version.h> to define them) so that only standard headers define them. For example, <bits/shared_ptr.h> will no longer define macros related to std::shared_ptr, only <memory> and <version> will define them. This means that __cpp_lib_shared_ptr_arrays will not be defined by <future> or by other headers that include <bits/shared_ptr.h>. It will only be defined when <memory> has been included. This will discourage users from relying on transitive includes. As a result, internal headers that need to query the macros should use the internal macros like __glibcxx_shared_ptr_arrays instead of __cpp_lib_shared_ptr_arrays, as those internal macros are defined by the internal headers after icluding <bits/version.h>. There are some exceptions to this rule, because __cpp_lib_is_constant_evaluated is defined by bits/c++config.h and so is available everywhere, and __cpp_lib_three_way_comparison is defined by <compare> which several headers are explicitly specified to include, so its macro is guaranteed to be usable too. N.B. not many internal headers actually need an explicit include of <bits/version.h>, because most of them include <type_traits> and so get all the __glibcxx_foo internal macros from there. libstdc++-v3/ChangeLog: * include/bits/algorithmfwd.h: Do not define standard feature test macro here. * include/bits/align.h: Likewise. Test internal macros instead of standard macros. * include/bits/alloc_traits.h: Likewise. * include/bits/allocator.h: Likewise. * include/bits/atomic_base.h: Likewise. * include/bits/atomic_timed_wait.h: Likewise. * include/bits/atomic_wait.h: Likewise. * include/bits/basic_string.h: Likewise. * include/bits/basic_string.tcc: Likewise. * include/bits/char_traits.h: Likewise. * include/bits/chrono.h: Likewise. * include/bits/cow_string.h: Likewise. * include/bits/forward_list.h: Likewise. * include/bits/hashtable.h: Likewise. * include/bits/ios_base.h: Likewise. * include/bits/memory_resource.h: Likewise. * include/bits/move.h: Likewise. * include/bits/move_only_function.h: Likewise. * include/bits/node_handle.h: Likewise. * include/bits/ptr_traits.h: Likewise. * include/bits/range_access.h: Likewise. * include/bits/ranges_algo.h: Likewise. * include/bits/ranges_cmp.h: Likewise. * include/bits/ranges_util.h: Likewise. * include/bits/semaphore_base.h: Likewise. * include/bits/shared_ptr.h: Likewise. * include/bits/shared_ptr_atomic.h: Likewise. * include/bits/shared_ptr_base.h: Likewise. * include/bits/stl_algo.h: Likewise. * include/bits/stl_algobase.h: Likewise. * include/bits/stl_function.h: Likewise. * include/bits/stl_iterator.h: Likewise. * include/bits/stl_list.h: Likewise. * include/bits/stl_map.h: Likewise. * include/bits/stl_pair.h: Likewise. * include/bits/stl_queue.h: Likewise. * include/bits/stl_stack.h: Likewise. * include/bits/stl_tree.h: Likewise. * include/bits/stl_uninitialized.h: Likewise. * include/bits/stl_vector.h: Likewise. * include/bits/unique_ptr.h: Likewise. * include/bits/unordered_map.h: Likewise. * include/bits/uses_allocator_args.h: Likewise. * include/bits/utility.h: Likewise. * include/bits/erase_if.h: Add comment. * include/std/algorithm: Define standard feature test macros here. * include/std/atomic: Likewise. * include/std/array: Likewise. * include/std/chrono: Likewise. * include/std/condition_variable: Likewise. * include/std/deque: Likewise. * include/std/format: Likewise. * include/std/functional: Likewise. * include/std/forward_list: Likewise. * include/std/ios: Likewise. * include/std/iterator: Likewise. * include/std/list: Likewise. * include/std/map: Likewise. * include/std/memory: Likewise. * include/std/numeric: Likewise. * include/std/queue: Likewise. * include/std/ranges: Likewise. * include/std/regex: Likewise. * include/std/set: Likewise. * include/std/stack: Likewise. * include/std/stop_token: Likewise. * include/std/string: Likewise. * include/std/string_view: * include/std/tuple: Likewise. * include/std/unordered_map: * include/std/unordered_set: * include/std/utility: Likewise. * include/std/vector: Likewise. * include/std/scoped_allocator: Query internal macros instead of standard macros.
This splits out the activate-the-union-member-for-constexpr logic from _M_use_local_data, so that it can be used separately in cases that don't need to use std::pointer_traits<pointer>::pointer_to to obtain the return value. This leaves only three uses of _M_use_local_data() which are all of the same form: __s._M_data(_M_use_local_data()); __s._M_set_length(0); We could remove _M_use_local_data() and change those three places to use a new _M_reset() function that does: _M_init_local_buf(); _M_data(_M_local_data()); _M_set_length(0); This is left for a future change. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (_M_init_local_buf()): New function. (_M_use_local_data()): Use _M_init_local_buf. (basic_string(), basic_string(const Alloc&)) (basic_string(basic_string&&)) (basic_string(basic_string&&, const Alloc&)): Use _M_init_local_buf instead of _M_use_local_data(). * include/bits/basic_string.tcc (swap(basic_string&)) (_M_construct(InIter, InIter, input_iterator_tag)) (_M_construct(InIter, InIter, forward_iterator_tag)) (_M_construct(size_type, CharT), reserve()): Likewise.