João Afonso questions

• Why doesn't the linker emit an error in the code below?
• Continuation of "I just can not understand DR 712"
• Why did they insist in using the `extern` specifier in the examples below?
• Is an int variable an object, according to the C++ Standard?
• Why does clang emit these warnings?
• I just can not understand DR 712
• VS2015 and clang compile this code, but g++ rejects it. Which one is correct?
• A compiling example of the hiding mentioned in the Note in [over.unary]/2
• Why do clang and g++ print 0 for a1.v and a2.v in this example in C++1z?
• The first snippet below compiles, but the second doesn't. Why?

João Afonso answers