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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r11-8502] libstdc++: Fix return value of std::ranges::advance [PR 100833] Date: Wed, 2 Jun 2021 13:43:36 +0000 (GMT) [thread overview] Message-ID: <20210602134336.344B83957055@sourceware.org> (raw) https://gcc.gnu.org/g:88ed4abb351117f3b7ef9174b3f538c73e6012c7 commit r11-8502-g88ed4abb351117f3b7ef9174b3f538c73e6012c7 Author: Jonathan Wakely <jwakely@redhat.com> Date: Tue Jun 1 16:02:45 2021 +0100 libstdc++: Fix return value of std::ranges::advance [PR 100833] The three-argument form of ranges::advance is supposed to return the difference between the second argument and the distance the iterator was advanced. When a non-random-access iterator is not advanced (because it already equals the sentinel) we were returning 0 rather than n - 0. libstdc++-v3/ChangeLog: PR libstdc++/100833 * include/bits/ranges_base.h (ranges::advance(iter, n, sentinel)): Fix return value for no-op case. * testsuite/24_iterators/range_operations/advance.cc: Test return values of three-argument overload. (cherry picked from commit d8326291695c0f13124c232ddf4fd34e3310e649) Diff: --- libstdc++-v3/include/bits/ranges_base.h | 2 +- .../24_iterators/range_operations/advance.cc | 48 ++++++++++++++-------- 2 files changed, 33 insertions(+), 17 deletions(-) diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h index 11f05fa4e2d..32d664f1a86 100644 --- a/libstdc++-v3/include/bits/ranges_base.h +++ b/libstdc++-v3/include/bits/ranges_base.h @@ -749,7 +749,7 @@ namespace ranges } } else if (__it == __bound || __n == 0) - return iter_difference_t<_It>(0); + return __n; else if (__n > 0) { iter_difference_t<_It> __m = 0; diff --git a/libstdc++-v3/testsuite/24_iterators/range_operations/advance.cc b/libstdc++-v3/testsuite/24_iterators/range_operations/advance.cc index e4abf83d59e..feee08b58c4 100644 --- a/libstdc++-v3/testsuite/24_iterators/range_operations/advance.cc +++ b/libstdc++-v3/testsuite/24_iterators/range_operations/advance.cc @@ -49,10 +49,12 @@ test01() std::ranges::advance(iter, r.begin()); VERIFY( iter == r.begin() ); - std::ranges::advance(iter, 99, r.end()); + auto diff = std::ranges::advance(iter, 99, r.end()); VERIFY( iter == r.end() ); - std::ranges::advance(iter, -222, r.begin()); + VERIFY( diff == 97 ); + diff = std::ranges::advance(iter, -222, r.begin()); VERIFY( iter == r.begin() ); + VERIFY( diff == -220 ); } void @@ -77,10 +79,12 @@ test02() std::ranges::advance(iter, r.begin()); VERIFY( iter == r.begin() ); - std::ranges::advance(iter, 99, r.end()); + auto diff = std::ranges::advance(iter, 99, r.end()); VERIFY( iter == r.end() ); - std::ranges::advance(iter, -222, r.begin()); + VERIFY( diff == 97 ); + diff = std::ranges::advance(iter, -222, r.begin()); VERIFY( iter == r.begin() ); + VERIFY( diff == -220 ); } void @@ -108,15 +112,19 @@ test03() std::ranges::advance(iter, r.end()); VERIFY( iter == r.end() ); - std::ranges::advance(iter, 99, r.end()); + auto diff = std::ranges::advance(iter, 99, r.end()); VERIFY( iter == r.end() ); - std::ranges::advance(iter, 99, r.end()); + VERIFY( diff == 99 ); // PR libstdc++/100833 + diff = std::ranges::advance(iter, 99, r.end()); VERIFY( iter == r.end() ); + VERIFY( diff == 99 ); iter = r.begin(); - std::ranges::advance(iter, 99, r.end()); + diff = std::ranges::advance(iter, 99, r.end()); VERIFY( iter == r.end() ); - std::ranges::advance(iter, 99, r.end()); + VERIFY( diff == 97 ); + diff = std::ranges::advance(iter, 99, r.end()); VERIFY( iter == r.end() ); + VERIFY( diff == 99 ); } void @@ -145,17 +153,21 @@ test04() std::ranges::advance(iter, r2.end()); VERIFY( iter == r2.end() ); - std::ranges::advance(iter, 99, r2.end()); + auto diff = std::ranges::advance(iter, 99, r2.end()); VERIFY( iter == r2.end() ); - std::ranges::advance(iter, 99, r2.end()); + VERIFY( diff == 99 ); + diff = std::ranges::advance(iter, 99, r2.end()); VERIFY( iter == r2.end() ); + VERIFY( diff == 99 ); test_range<int, input_iterator_wrapper> r3(a); iter = r3.begin(); - std::ranges::advance(iter, 99, r3.end()); + diff = std::ranges::advance(iter, 99, r3.end()); VERIFY( iter == r3.end() ); - std::ranges::advance(iter, 99, r3.end()); + VERIFY( diff == 97 ); + diff = std::ranges::advance(iter, 99, r3.end()); VERIFY( iter == r3.end() ); + VERIFY( diff == 99 ); } void @@ -180,17 +192,21 @@ test05() std::ranges::advance(iter, r2.end()); VERIFY( iter == r2.end() ); - std::ranges::advance(iter, 99, r2.end()); + auto diff = std::ranges::advance(iter, 99, r2.end()); VERIFY( iter == r2.end() ); - std::ranges::advance(iter, 99, r2.end()); + VERIFY( diff == 99 ); + diff = std::ranges::advance(iter, 99, r2.end()); VERIFY( iter == r2.end() ); + VERIFY( diff == 99 ); test_range<int, output_iterator_wrapper> r3(a); iter = r3.begin(); - std::ranges::advance(iter, 99, r3.end()); + diff = std::ranges::advance(iter, 99, r3.end()); VERIFY( iter == r3.end() ); - std::ranges::advance(iter, 99, r3.end()); + VERIFY( diff == 97 ); + diff = std::ranges::advance(iter, 99, r3.end()); VERIFY( iter == r3.end() ); + VERIFY( diff == 99 ); } int
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