clang: What does emitting mean?

Question

The clang diagnostics reference uses the word emit three times. The following warnings use this term.

Example 1: Compile this with -Wunneeded-internal-declaration -Wunneeded-member-function:

namespace {
    int x;
    int F();

    struct A {
        void M();
    };
}


decltype(x)     global1;
decltype(F())   global2;
decltype(&A::M) global3;

You get the following warnings:

warning: variable 'x' is not needed and will not be emitted
warning: function 'F' is not needed and will not be emitted
warning: member function 'M' is not needed and will not be emitted

Example 2: Compile this with -Wweak-vtables:

class Apple {
    virtual ~Apple() {}
};

You get the following warning:

warning: 'Apple' has no out-of-line virtual method definitions; its vtable will be emitted in every translation unit

Question

What does emitting mean?

The most straightforward explanation would be: emitting = generating assembly code. But there are some open questions, if we examine the details.

• In example 1 if we do not use x, F and A::M in unevaluated context, the warnings disappear. So the warning has to do something with unevaluated context.
• In example 1 F and M are only declarations. Compiler never generates assembly code from a function declaration. So there is no point in giving a warning about it.
• Clang has separate warnings for the case when a variable or function can be proven not to be used. Compile with -Wunused (example). No assembly code is generated from the variable and the function, and the warnings do not use the term emit.
• The warnings that come from -Wunused are reported for definitions and not declarations.

I do not fully understand example 2. I put it here for the sake of completeness. Emitting might mean a slightly different thing here.

Could someone, maybe a clang contributor give some clarification about these questions?