https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69855
Bug ID: 69855
Summary: Missing diagnostic for overload that only differs by
return type
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Keywords: accepts-invalid
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
The following code intended to create a local mutex but instead declared a
function:
#include <mutex>
std::mutex& get();
void f()
{
std::lock_guard<std::mutex>(get());
// oops! mutex not locked
}
But this should be invalid, because get() is already declared in the enclosing
scope and the return type is not the same. By failing to diagnose this error we
allow the code above to compile and run without locking the mutex.
Reduced:
struct mutex { };
mutex& get();
struct guard {
guard(mutex&) { }
};
void f()
{
guard(get());
}
Clang says:
ww.cc:12:9: error: functions that differ only in their return type cannot be
overloaded
guard(get());
^
ww.cc:4:8: note: previous declaration is here
mutex& get();
~~~~~~ ^
1 error generated.
EDG says:
"ww.cc", line 12: error: declaration is incompatible with previous "get"
(declared at line 4)
guard(get());
^
1 error detected in the compilation of "ww.cc".
