check lifetime bound of TString const iterators

ex:
```
auto it = TString{"temporary"}.cbegin();
use(*it);
```
commit_hash:68f621e7b2d608340d7b9f5a9a246c138a2eafff

1 files changed, 30 insertions, 8 deletions

diff --git a/util/generic/string.h b/util/generic/string.h
index 5fe507200d..b73c73e625 100644
--- a/util/generic/string.h
+++ b/util/generic/string.h
@@ -325,14 +325,36 @@ public:
         return reverse_iterator(begin());
     }
 
-    using TBase::begin;   //!< const_iterator TStringBase::begin() const
-    using TBase::cbegin;  //!< const_iterator TStringBase::cbegin() const
-    using TBase::cend;    //!< const_iterator TStringBase::cend() const
-    using TBase::crbegin; //!< const_reverse_iterator TStringBase::crbegin() const
-    using TBase::crend;   //!< const_reverse_iterator TStringBase::crend() const
-    using TBase::end;     //!< const_iterator TStringBase::end() const
-    using TBase::rbegin;  //!< const_reverse_iterator TStringBase::rbegin() const
-    using TBase::rend;    //!< const_reverse_iterator TStringBase::rend() const
+    const_iterator begin() const noexcept Y_LIFETIME_BOUND {
+        return TBase::begin();
+    }
+    const_iterator cbegin() const noexcept Y_LIFETIME_BOUND {
+        return TBase::cbegin();
+    }
+
+    const_iterator cend() const noexcept Y_LIFETIME_BOUND {
+        return TBase::cend();
+    }
+
+    const_reverse_iterator crbegin() const noexcept Y_LIFETIME_BOUND {
+        return TBase::crbegin();
+    }
+
+    const_reverse_iterator crend() const noexcept Y_LIFETIME_BOUND {
+        return TBase::crend();
+    }
+
+    const_iterator end() const noexcept Y_LIFETIME_BOUND {
+        return TBase::end();
+    }
+
+    const_reverse_iterator rbegin() const noexcept Y_LIFETIME_BOUND {
+        return TBase::rbegin();
+    }
+
+    const_reverse_iterator rend() const noexcept Y_LIFETIME_BOUND {
+        return TBase::rend();
+    }
 
     inline size_t capacity() const noexcept {
 #ifdef TSTRING_IS_STD_STRING