[LLVMbugs] [Bug 22021] libc++ std::ostrstream leaks memory.
bugzilla-daemon at llvm.org
bugzilla-daemon at llvm.org
Wed Dec 24 11:31:22 PST 2014
http://llvm.org/bugs/show_bug.cgi?id=22021
Marshall Clow (home) <mclow.lists at gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |INVALID
--- Comment #1 from Marshall Clow (home) <mclow.lists at gmail.com> ---
This is a "required" memory leak (if you can believe that).
When you call strstreambuf::str() (which ostrstream is derived from), you get a
pointer to its internal buffer, and the stream is "frozen" (see
depr.strstreambuf.members/2 in the standard). Note that in spite of the method
being named "str", it does NOT return a std::string.
When the stream is destructed, the buffer may not be freed if the stream is
"frozen".
(see depr.strstreambuf.cons/8).
If you rewrite your code thus:
static std::string MessageComposer( uint32_t index )
{
std::ostrstream stm;
stm << "This is message #" << index << "." << std::endl;
std::string foo = stm.str();
stm.freeze(false);
return foo;
}
you will see that the "leak" has disappeared.
(Yeah, it's easy to misuse this object. Maybe that's why it is deprecated)
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