On Mon, 12 Feb 2024 at 22:17, Patrick Palka <ppa...@redhat.com> wrote:
> On Mon, 12 Feb 2024, Paul Keir wrote: > > > A call to `basic_string::clear()` in the std::string move assignment > operator leads to a constexpr error from an access of inactive union member > `_M_local_buf` in the added test (`test_move()`). Changing > `__str._M_local_buf` to `__str._M_use_local_data()` in > `operator=(basic_string&& __str)` fixes this. > > > > Running `make check > RUNTESTFLAGS="conformance.exp=21_strings/basic_string/*"` on > x86_64-pc-linux-gnu gave unchanged summary results (# of expected passes > 570 # of expected failures 4 # of unsupported tests 4). > > > > I don't have write access. > > > > Signed-off-by: Paul Keir <paul.k...@uws.ac.uk> > > LGTM! A ChangeLog entry is missing from the commit message, > so here's one that we can use for this commit: > > PR libstdc++/113294 > > libstdc++-v3/ChangeLog: > > * include/bits/basic_string.h (basic_string::operator=): Use > _M_use_local_data() instead of _M_local_buf on the moved-from > string. > * testsuite/21_strings/basic_string/modifiers/constexpr.cc > (test_move): New test. > The patch is OK for trunk and gcc-13 with that commit msg. Patrick, could you push it for Paul? Thank you both. > > > > diff --git a/libstdc++-v3/include/bits/basic_string.h > b/libstdc++-v3/include/bits/basic_string.h > > index 43efc99bea9..8a695a494ef 100644 > > --- a/libstdc++-v3/include/bits/basic_string.h > > +++ b/libstdc++-v3/include/bits/basic_string.h > > @@ -909,7 +909,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 > > __str._M_capacity(__capacity); > > } > > else > > - __str._M_data(__str._M_local_buf); > > + __str._M_data(__str._M_use_local_data()); > > } > > else // Need to do a deep copy > > assign(__str); > > diff --git > a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/constexpr.cc > b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/constexpr.cc > > index 0e28a6d4487..ad7548f3236 100644 > > --- > a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/constexpr.cc > > +++ > b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/constexpr.cc > > @@ -50,3 +50,16 @@ test_erasure() > > } > > > > static_assert( test_erasure() ); > > + > > +constexpr bool > > +test_move() > > +{ > > + std::string s1; > > + std::string s2 = "1234567890123456"; // 16 chars: more than > _S_local_capacity > > + s1 = std::move(s2); > > + VERIFY( s1 == "1234567890123456" ); > > + > > + return true; > > +} > > + > > +static_assert( test_move() ); > > -- > > > > > > Please consider the environment and think before you print. > > > > The University of the West of Scotland is a registered Scottish charity. > Charity number SC002520. > > > > This e-mail and any attachment is for authorised use by the intended > recipient(s) only. It may contain proprietary material, confidential > information and/or be subject to legal privilege. It should not be copied, > disclosed to, retained or used by, any other party. If you are not an > intended recipient then please promptly delete this e-mail and any > attachment and all copies and inform the sender. > > > > Please note that any views or opinions presented in this email are > solely those of the author and do not necessarily represent those of the > University of the West of Scotland. > > > > As a public body, the University of the West of Scotland may be required > to make available emails as well as other written forms of information as a > result of a request made under the Freedom of Information (Scotland) Act > 2002. > > > > > >