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[cologic <518165@xxxxxxxxxxxxxxxxxx>]

** Changed in: dcplusplus
       Status: Confirmed => Fix Released

-- 
Compiling DC++ in release mode (-O2) with g++ 4.4 spews type-punning/aliasing warnings
https://bugs.launchpad.net/bugs/518165
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Status in DC++: Fix Released

Bug description:
They're mostly in include files, so they keep occurring and swamping any other warnings' visibilities. There's always -fno-string-aliasing but http://gcc.gnu.org/ml/gcc-help/2006-08/msg00240.html makes a good case for their more general danger, that g++ isn't just whinging here. Especially the Tree.h:354 warning and CID.h:41 warnings make it actively harder to take advantage of the diagnostics g++ automatically provides for DC++ code.

This one happens a few times:
In file included from win32\stdafx.h:53:
dwt\include/dwt/widgets/Tree.h: In member function 'dwt::Rectangle dwt::Tree::getItemRect(_TREEITEM*)':
dwt\include/dwt/widgets/Tree.h:354: warning: dereferencing type-punned pointer will break strict-aliasing rules

The line 354 is the TreeView_GetItemRect line in:
inline Rectangle Tree::getItemRect(HTREEITEM item) {
	RECT rc;
	TreeView_GetItemRect(handle(), item, &rc, TRUE);
	return Rectangle(rc);
}

This one happens dozens of times, because CID.h is such a central file:
dcpp\CID.h: In member function 'size_t dcpp::CID::toHash() const':
dcpp\CID.h:41: warning: dereferencing type-punned pointer will break strict-aliasing rules

Line 41: size_t toHash() const { return *reinterpret_cast<const size_t*>(cid); }

This pair comes up less frequently, but still a few times:
dcpp\HashValue.h:52: warning: dereferencing type-punned pointer will break strict-aliasing rules
dcpp\HashValue.h:52: warning: dereferencing pointer '<anonymous>' does break strict-aliasing rules

The line in question is the operator() declaration&definition:
template<typename T>
struct hash<dcpp::HashValue<T> > {
	size_t operator()(const dcpp::HashValue<T>& rhs) const { return *(size_t*)rhs.data; }
};

This one is unique to DateTime.cpp:
dwt\src\util\DateTime.cpp: In function 'dwt::util::DateTime dwt::util::operator+(const dwt::util::Da
teTime&, const dwt::util::TimeSpan&)':
dwt\src\util\DateTime.cpp:173: warning: dereferencing type-punned pointer will break strict-aliasing rules
dwt\src\util\DateTime.cpp: In function 'dwt::util::DateTime dwt::util::operator-(const dwt::util::DateTime&, const dwt::util::TimeSpan&)':
dwt\src\util\DateTime.cpp:188: warning: dereferencing type-punned pointer will break strict-aliasing rules
dwt\src\util\DateTime.cpp:192: warning: dereferencing pointer 'tmpVal' does break strict-aliasing rules
dwt\src\util\DateTime.cpp:188: note: initialized from here
dwt\src\util\DateTime.cpp: In function 'dwt::util::DateTime dwt::util::operator+(const dwt::util::DateTime&, const dwt::util::TimeSpan&)':
dwt\src\util\DateTime.cpp:177: warning: dereferencing pointer 'tmpVal' does break strict-aliasing rules
dwt\src\util\DateTime.cpp:173: note: initialized from here

Not going to copy/paste all of that code, but it's generically similar to that already shown.