https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80635
--- Comment #22 from Jonathan Wakely <redi at gcc dot gnu.org> ---
From Bug 92011:
cat > t.cc <<EOF
#include <optional>
struct Bar
{
int size_;
Bar( int size )
: size_( size )
{}
};
template<class T>
Bar get( T const& val )
{
return Bar( __builtin_strlen(val) );
}
class Foo
{
int size2_;
public:
Foo()
{}
template<class T>
Foo( T const& t )
: size2_( get<T>( t ).size_ )
{}
};
enum Enum
{};
bool parseImpl2( Foo s, Enum* val )
{
*val = Enum();
for(;;)
{
s = "aa";
if( true )
return false;
return true;
}
}
template<class T> std::optional<T> parse2( Foo str )
{
T res = T();
if( parseImpl2( str, &res ) )
return res;
return std::optional<T>();
}
Enum transform()
{
if( auto r = parse2<Enum>( Foo() ) )
return *r;
return {};
}
EOF
gcc -std=c++17 -c -o t.cc.o t.cc -Wall -O1
####
Gives:
t.cc: In function 'Enum transform()':
t.cc:50:27: warning: '<anonymous>' may be used uninitialized in this function
[-Wmaybe-uninitialized]
50 | return std::optional<T>();
| ^
