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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/102048] __gnu_cxx::rope.erase(size_t __p)
 implementation seems to be wrong
Date: Tue, 24 Aug 2021 19:12:58 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102048

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-08-24
             Status|UNCONFIRMED                 |NEW

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This would fix it, and provide the API that was apparently intended:

--- a/libstdc++-v3/include/ext/rope
+++ b/libstdc++-v3/include/ext/rope
@@ -2401,11 +2401,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        this->_M_tree_ptr =3D __result;
       }

-      // Erase, single character
-      void
-      erase(size_type __p)
-      { erase(__p, __p + 1); }
-
       // Insert, iterator variants.
       iterator
       insert(const iterator& __p, const rope& __r)


If we want to retain an erase function that erases a single character, we c=
ould
do:

@@ -2393,7 +2393,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION

       // Erase, (position, size) variant.
       void
-      erase(size_type __p, size_type __n)
+      erase(size_type __p, size_type __n =3D 1)
       {
        _RopeRep* __result =3D replace(this->_M_tree_ptr, __p,
                                     __p + __n, 0);


But to be consistent with std::string it should erase from that position to=
 the
end of the string:

@@ -2393,7 +2393,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION

       // Erase, (position, size) variant.
       void
-      erase(size_type __p, size_type __n)
+      erase(size_type __p, size_type __n =3D npos)
       {
        _RopeRep* __result =3D replace(this->_M_tree_ptr, __p,
                                     __p + __n, 0);

So maybe we should just remove it, since it's currently broken and "fixing"=
 it
would be inconsistent with std::string.=