On Wed, 29 Jan 2020, Patrick Palka wrote: > On Wed, 29 Jan 2020, Jonathan Wakely wrote: > >> On 21/01/20 17:26 -0500, Patrick Palka wrote: >>> It seems that in practice std::sentinel_for is always true, and so >>> the >> >> Doh, good catch. >> >>> test_range container doesn't help us detect bugs in ranges code in which >>> we >>> wrongly assume that a sentinel can be manipulated like an iterator. Make >>> the >>> test_range container more strict by having end() unconditionally return a >>> sentinel. >> >> Yes, this seems useful. >> >>> Is this OK to commit after bootstrap+regtesting succeeds on >>> x86_64-pc-linux-gnu? >> >> As you mentioned on IRC, this makes some tests fail. >> >> Some of them are bad tests and this change reveals that, e.g. >> std/ranges/access/end.cc should not assume that r.end()==r.end() is >> valid (because sentinels can't be compared with sentinels). >> >> In other cases, the test is intentionally relying on the fact the >> r.end() returns the same type as r.begin(), e.g. in >> std/ranges/access/rbegin.cc we want to test this case: >> >> — Otherwise, make_reverse_iterator(ranges::end(t)) if both >> ranges::begin(t) and ranges::end(t) are valid expressions of the same >> type I which models bidirectional_iterator (23.3.4.12). >> >> If the sentinel returned by ranges::end(r) is a different type, we >> can't use test_range to verify this part of the ranges::rbegin >> requirements. >> >> I think we do want your change, so this patch fixes the tests that >> inappropriately assume the sentinel is the same type as the iterator. >> When we are actually relying on that property for the test, I'm adding >> a new type derived from test_range which provides that guarantee and >> using that instead. >> >> There's one final change needed to make std/ranges/access/size.cc >> compile after your patch, which is to make the test_range::sentinel >> type satisfy std::sized_sentinel_for when the iterator satisfies >> std::random_access_iterator, i.e. support subtracting iterators and >> sentinels from each other. >> >> Tested powerpc64le-linux, committed to trunk. > > Thanks for the review and the testsuite fixes. > >> >> Please go ahead and commit your patch to test_range::end() after >> re-testing. Thanks, and congratulations on your first libstdc++ >> patch. > > Thanks! :) I am re-testing now, and will commit the patch after that's > done. It looks like there are other testsuite failures that need to get addressed, in particular in the tests range_operations/{prev,distance,next}.cc. In prev.cc and next.cc we are passing a sentinel as the first argument to ranges::next and ranges::prev, which expect an iterator as their first argument. In distance.cc we're passing a sentinel as the first argument to ranges::distance, which also expects an iterator as its first argument. Here's an updated patch that adjusts these tests in the straightforward way. In test04() in next.cc I had to reset the bounds on the container after doing ranges::next(begin, end) since we're manipulating an input_iterator_wrapper. Is this OK to commit? -- >8 -- Subject: [PATCH] libstdc++: Always return a sentinel from __gnu_test::test_range::end() It seems that in practice std::sentinel_for is always true, and so the test_range container doesn't help us detect bugs in ranges code in which we wrongly assume that a sentinel can be manipulated like an iterator. Make the test_range range more strict by having end() unconditionally return a sentinel, and adjust some tests accordingly. libstdc++-v3/ChangeLog: * testsuite/24_iterators/range_operations/distance.cc: Do not assume test_range::end() returns the same type as test_range::begin(). * testsuite/24_iterators/range_operations/next.cc: Likewise. * testsuite/24_iterators/range_operations/prev.cc: Likewise. * testsuite/util/testsuite_iterators.h (__gnu_test::test_range::end): Always return a sentinel. --- .../24_iterators/range_operations/distance.cc | 30 ++++++---- .../24_iterators/range_operations/next.cc | 57 ++++++++++--------- .../24_iterators/range_operations/prev.cc | 50 ++++++++-------- .../testsuite/util/testsuite_iterators.h | 5 +- 4 files changed, 78 insertions(+), 64 deletions(-) diff --git a/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc b/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc index 754c0cc200b..cf251b04ec5 100644 --- a/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc +++ b/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc @@ -39,13 +39,17 @@ test01() test_range c(a); VERIFY( std::ranges::distance(c) == 10 ); - auto b = c.begin(), e = c.end(); + auto b = c.begin(); + auto e = c.end(); + auto ei = std::ranges::next(b, e); VERIFY( std::ranges::distance(b, e) == 10 ); - VERIFY( std::ranges::distance(e, b) == -10 ); + VERIFY( std::ranges::distance(ei, b) == -10 ); - const auto cb = b, ce = e; + const auto cb = b; + const auto ce = e; + const auto cei = ei; VERIFY( std::ranges::distance(cb, ce) == 10 ); - VERIFY( std::ranges::distance(ce, cb) == -10 ); + VERIFY( std::ranges::distance(cei, cb) == -10 ); test_sized_range c2(a); VERIFY( std::ranges::distance(c2) == 10 ); @@ -60,10 +64,12 @@ test02() test_range c(a); VERIFY( std::ranges::distance(c) == 2 ); - auto b = c.begin(), e = c.end(); + auto b = c.begin(); + auto e = c.end(); VERIFY( std::ranges::distance(b, e) == 2 ); - const auto cb = b, ce = e; + const auto cb = b; + const auto ce = e; VERIFY( std::ranges::distance(cb, ce) == 2 ); test_sized_range c2(a); @@ -77,10 +83,12 @@ test03() test_range c(a); VERIFY( std::ranges::distance(c) == 3 ); - auto b = c.begin(), e = c.end(); + auto b = c.begin(); + auto e = c.end(); VERIFY( std::ranges::distance(b, e) == 3 ); - const auto cb = b, ce = e; + const auto cb = b; + const auto ce = e; VERIFY( std::ranges::distance(cb, ce) == 3 ); test_sized_range c2(a); @@ -99,11 +107,13 @@ test04() VERIFY( std::ranges::distance(c) == 0 ); c = test_range(a); - auto b = c.begin(), e = c.end(); + auto b = c.begin(); + auto e = c.end(); VERIFY( std::ranges::distance(b, e) == 4 ); test_range c2(a); - const auto cb = c2.begin(), ce = c2.end(); + const auto cb = c2.begin(); + const auto ce = c2.end(); VERIFY( std::ranges::distance(cb, ce) == 4 ); test_sized_range c3(a); diff --git a/libstdc++-v3/testsuite/24_iterators/range_operations/next.cc b/libstdc++-v3/testsuite/24_iterators/range_operations/next.cc index af4ae7eacdb..d3fe7b47150 100644 --- a/libstdc++-v3/testsuite/24_iterators/range_operations/next.cc +++ b/libstdc++-v3/testsuite/24_iterators/range_operations/next.cc @@ -36,27 +36,28 @@ test01() test_range r(a); auto begin = r.begin(); auto end = r.end(); + auto endi = std::ranges::next(begin, end); VERIFY( *std::ranges::next(begin) == 1 ); VERIFY( std::ranges::next(begin, 0) == begin ); VERIFY( *std::ranges::next(begin, 1) == 1 ); VERIFY( *std::ranges::next(begin, 3) == 3 ); - VERIFY( *std::ranges::next(end, -4) == 6 ); + VERIFY( *std::ranges::next(endi, -4) == 6 ); VERIFY( std::ranges::next(begin, begin) == begin ); VERIFY( std::ranges::next(begin, end) == end ); - VERIFY( std::ranges::next(end, end) == end ); - VERIFY( std::ranges::next(end, begin) == begin ); + VERIFY( std::ranges::next(endi, end) == end ); + VERIFY( std::ranges::next(endi, begin) == begin ); VERIFY( std::ranges::next(begin, 0, begin) == begin ); VERIFY( std::ranges::next(begin, 5, begin) == begin ); VERIFY( std::ranges::next(begin, -5, begin) == begin ); VERIFY( std::ranges::next(begin, 0, end) == begin ); VERIFY( *std::ranges::next(begin, 5, end) == 5 ); VERIFY( std::ranges::next(begin, 55, end) == end ); - VERIFY( std::ranges::next(end, 0, end) == end ); - VERIFY( std::ranges::next(end, -5, end) == end ); - VERIFY( std::ranges::next(end, -55, end) == end ); - VERIFY( std::ranges::next(end, 0, begin) == end ); - VERIFY( *std::ranges::next(end, -5, begin) == 5 ); - VERIFY( std::ranges::next(end, -55, begin) == begin ); + VERIFY( std::ranges::next(endi, 0, end) == end ); + VERIFY( std::ranges::next(endi, -5, end) == end ); + VERIFY( std::ranges::next(endi, -55, end) == end ); + VERIFY( std::ranges::next(endi, 0, begin) == end ); + VERIFY( *std::ranges::next(endi, -5, begin) == 5 ); + VERIFY( std::ranges::next(endi, -55, begin) == begin ); } void @@ -66,27 +67,28 @@ test02() test_range r(a); auto begin = r.begin(); auto end = r.end(); + auto endi = std::ranges::next(begin, end); VERIFY( *std::ranges::next(begin) == 1 ); VERIFY( std::ranges::next(begin, 0) == begin ); VERIFY( *std::ranges::next(begin, 1) == 1 ); VERIFY( *std::ranges::next(begin, 3) == 3 ); - VERIFY( *std::ranges::next(end, -4) == 6 ); + VERIFY( *std::ranges::next(endi, -4) == 6 ); VERIFY( std::ranges::next(begin, begin) == begin ); VERIFY( std::ranges::next(begin, end) == end ); - VERIFY( std::ranges::next(end, end) == end ); - VERIFY( std::ranges::next(end, begin) == begin ); + VERIFY( std::ranges::next(endi, end) == end ); + VERIFY( std::ranges::next(endi, begin) == begin ); VERIFY( std::ranges::next(begin, 0, begin) == begin ); VERIFY( std::ranges::next(begin, 5, begin) == begin ); VERIFY( std::ranges::next(begin, -5, begin) == begin ); VERIFY( std::ranges::next(begin, 0, end) == begin ); VERIFY( *std::ranges::next(begin, 5, end) == 5 ); VERIFY( std::ranges::next(begin, 55, end) == end ); - VERIFY( std::ranges::next(end, 0, end) == end ); - VERIFY( std::ranges::next(end, -5, end) == end ); - VERIFY( std::ranges::next(end, -55, end) == end ); - VERIFY( std::ranges::next(end, 0, begin) == end ); - VERIFY( *std::ranges::next(end, -5, begin) == 5 ); - VERIFY( std::ranges::next(end, -55, begin) == begin ); + VERIFY( std::ranges::next(endi, 0, end) == end ); + VERIFY( std::ranges::next(endi, -5, end) == end ); + VERIFY( std::ranges::next(endi, -55, end) == end ); + VERIFY( std::ranges::next(endi, 0, begin) == end ); + VERIFY( *std::ranges::next(endi, -5, begin) == 5 ); + VERIFY( std::ranges::next(endi, -55, begin) == begin ); } void @@ -96,23 +98,24 @@ test03() test_range r(a); auto begin = r.begin(); auto end = r.end(); + auto endi = std::ranges::next(begin, end); VERIFY( *std::ranges::next(begin) == 1 ); VERIFY( std::ranges::next(begin, 0) == begin ); VERIFY( *std::ranges::next(begin, 1) == 1 ); VERIFY( *std::ranges::next(begin, 3) == 3 ); VERIFY( std::ranges::next(begin, begin) == begin ); VERIFY( std::ranges::next(begin, end) == end ); - VERIFY( std::ranges::next(end, end) == end ); + VERIFY( std::ranges::next(endi, end) == end ); VERIFY( std::ranges::next(begin, 0, begin) == begin ); VERIFY( std::ranges::next(begin, 5, begin) == begin ); VERIFY( std::ranges::next(begin, -5, begin) == begin ); VERIFY( std::ranges::next(begin, 0, end) == begin ); VERIFY( *std::ranges::next(begin, 5, end) == 5 ); VERIFY( std::ranges::next(begin, 55, end) == end ); - VERIFY( std::ranges::next(end, 0, end) == end ); - VERIFY( std::ranges::next(end, 5, end) == end ); - VERIFY( std::ranges::next(end, 55, end) == end ); - VERIFY( std::ranges::next(end, 0, begin) == end ); + VERIFY( std::ranges::next(endi, 0, end) == end ); + VERIFY( std::ranges::next(endi, 5, end) == end ); + VERIFY( std::ranges::next(endi, 55, end) == end ); + VERIFY( std::ranges::next(endi, 0, begin) == end ); } void @@ -141,6 +144,8 @@ test04() test_range r2(a); begin = r2.begin(); end = r2.end(); + auto endi = std::ranges::next(begin, end); + r2.bounds.first = a; iter = std::ranges::next(begin, 0, begin); VERIFY( *iter == 0 ); iter = std::ranges::next(begin, 5, begin); @@ -149,15 +154,15 @@ test04() VERIFY( *iter == 0 ); iter = std::ranges::next(begin, 0, end); VERIFY( *iter == 0 ); - iter = std::ranges::next(end, 0, begin); + iter = std::ranges::next(endi, 0, begin); VERIFY( iter == end ); iter = std::ranges::next(begin, 5, end); // invalidates begin VERIFY( *iter == 5 ); iter = std::ranges::next(iter, 55, end); VERIFY( iter == end ); - iter = std::ranges::next(end, 0, end); + iter = std::ranges::next(endi, 0, end); VERIFY( iter == end ); - iter = std::ranges::next(end, 5, end); + iter = std::ranges::next(endi, 5, end); VERIFY( iter == end ); } diff --git a/libstdc++-v3/testsuite/24_iterators/range_operations/prev.cc b/libstdc++-v3/testsuite/24_iterators/range_operations/prev.cc index ebf7c3f1323..70064b1b810 100644 --- a/libstdc++-v3/testsuite/24_iterators/range_operations/prev.cc +++ b/libstdc++-v3/testsuite/24_iterators/range_operations/prev.cc @@ -36,23 +36,24 @@ test01() test_range r(a); auto begin = r.begin(); auto end = r.end(); - VERIFY( *std::ranges::prev(end) == 9 ); + auto endi = std::ranges::next(begin, end); + VERIFY( *std::ranges::prev(endi) == 9 ); VERIFY( std::ranges::prev(begin, 0) == begin ); - VERIFY( *std::ranges::prev(end, 1) == 9 ); - VERIFY( *std::ranges::prev(end, 3) == 7 ); + VERIFY( *std::ranges::prev(endi, 1) == 9 ); + VERIFY( *std::ranges::prev(endi, 3) == 7 ); VERIFY( *std::ranges::prev(begin, -4) == 4 ); VERIFY( std::ranges::prev(begin, 0, begin) == begin ); VERIFY( std::ranges::prev(begin, 5, begin) == begin ); VERIFY( std::ranges::prev(begin, -5, begin) == begin ); - VERIFY( std::ranges::prev(begin, 0, end) == begin ); - VERIFY( *std::ranges::prev(end, 5, begin) == 5 ); - VERIFY( std::ranges::prev(end, 55, begin) == begin ); - VERIFY( std::ranges::prev(end, 0, end) == end ); - VERIFY( std::ranges::prev(end, -5, end) == end ); - VERIFY( std::ranges::prev(end, -55, end) == end ); - VERIFY( std::ranges::prev(end, 0, begin) == end ); - VERIFY( *std::ranges::prev(begin, -5, end) == 5 ); - VERIFY( std::ranges::prev(begin, -55, end) == end ); + VERIFY( std::ranges::prev(begin, 0, endi) == begin ); + VERIFY( *std::ranges::prev(endi, 5, begin) == 5 ); + VERIFY( std::ranges::prev(endi, 55, begin) == begin ); + VERIFY( std::ranges::prev(endi, 0, endi) == end ); + VERIFY( std::ranges::prev(endi, -5, endi) == end ); + VERIFY( std::ranges::prev(endi, -55, endi) == end ); + VERIFY( std::ranges::prev(endi, 0, begin) == end ); + VERIFY( *std::ranges::prev(begin, -5, endi) == 5 ); + VERIFY( std::ranges::prev(begin, -55, endi) == end ); } void @@ -62,23 +63,24 @@ test02() test_range r(a); auto begin = r.begin(); auto end = r.end(); - VERIFY( *std::ranges::prev(end) == 9 ); + auto endi = std::ranges::next(begin, end); + VERIFY( *std::ranges::prev(endi) == 9 ); VERIFY( std::ranges::prev(begin, 0) == begin ); - VERIFY( *std::ranges::prev(end, 1) == 9 ); - VERIFY( *std::ranges::prev(end, 3) == 7 ); + VERIFY( *std::ranges::prev(endi, 1) == 9 ); + VERIFY( *std::ranges::prev(endi, 3) == 7 ); VERIFY( *std::ranges::prev(begin, -4) == 4 ); VERIFY( std::ranges::prev(begin, 0, begin) == begin ); VERIFY( std::ranges::prev(begin, 5, begin) == begin ); VERIFY( std::ranges::prev(begin, -5, begin) == begin ); - VERIFY( std::ranges::prev(begin, 0, end) == begin ); - VERIFY( *std::ranges::prev(end, 5, begin) == 5 ); - VERIFY( std::ranges::prev(end, 55, begin) == begin ); - VERIFY( std::ranges::prev(end, 0, end) == end ); - VERIFY( std::ranges::prev(end, -5, end) == end ); - VERIFY( std::ranges::prev(end, -55, end) == end ); - VERIFY( std::ranges::prev(end, 0, begin) == end ); - VERIFY( *std::ranges::prev(begin, -5, end) == 5 ); - VERIFY( std::ranges::prev(begin, -55, end) == end ); + VERIFY( std::ranges::prev(begin, 0, endi) == begin ); + VERIFY( *std::ranges::prev(endi, 5, begin) == 5 ); + VERIFY( std::ranges::prev(endi, 55, begin) == begin ); + VERIFY( std::ranges::prev(endi, 0, endi) == end ); + VERIFY( std::ranges::prev(endi, -5, endi) == end ); + VERIFY( std::ranges::prev(endi, -55, endi) == end ); + VERIFY( std::ranges::prev(endi, 0, begin) == end ); + VERIFY( *std::ranges::prev(begin, -5, endi) == 5 ); + VERIFY( std::ranges::prev(begin, -55, endi) == end ); } template diff --git a/libstdc++-v3/testsuite/util/testsuite_iterators.h b/libstdc++-v3/testsuite/util/testsuite_iterators.h index 1c7fbd001e0..6887d806a31 100644 --- a/libstdc++-v3/testsuite/util/testsuite_iterators.h +++ b/libstdc++-v3/testsuite/util/testsuite_iterators.h @@ -710,10 +710,7 @@ namespace __gnu_test auto end() & { using I = decltype(get_iterator(bounds.last)); - if constexpr (std::sentinel_for) - return get_iterator(bounds.last); - else - return sentinel{bounds.last}; + return sentinel{bounds.last}; } typename Iter::ContainerType bounds; -- 2.25.0.24.gbc7a3d4dc0