What is the part of a full-expression?

Consider this example

#include <iostream>
struct A{
   A(){
       std::cout<<"A ctor\n";
   }
   ~A(){
       std::cout<<"A dtor\n";
   }
};
int fun(A const&){
    std::cout<<"abc\n";
    return 0;
}
void show(double, int){
    std::cout<<"show\n";
}
int main() {
   show(0,fun(A{}));  // #1
}

According to the result, it is observable that the temporary object is destroyed at the completion of #1. According to [class.temporary] p6

The exceptions to this lifetime rule are:

• A temporary object bound to a reference parameter in a function call ([expr.call]) persists until the completion of the full-expression containing the call.

I wonder why is show(0,fun(A{})); the full-expression of fun(A{})? According to [basic.exec#intro.execution-5]

A full-expression is

-[...]

• an expression that is not a subexpression of another expression and that is not otherwise part of a full-expression.

show(0,fun(A{})); is a full-expression, however, the function call fun(A{}) that is an argument of the function call of show is not a subexpression of the enclosing function call(if explicitly specified arguments are not operands of a function call). The definition of part of a full-expression is also not clear in the standard.

I have the following concerns:

• Are arguments considered to be operands of the function call?

the answers in C standard seems to say they are not

• What is the part of a full-expression?