about function declaration

Dear all,

Considering the follwing codes:
//////////////////////////////////////////////////////////////////code begin
int fun(int i){
return i++;
int main(){
int j = 0;
j = fun(j);
//////////////////////////////////////////////////////////////////code end

In the “StaticAnalyzer/AnalysisConsumer.cpp”, there are two function declarations about the code. One function declaration is about the function —“fun”, and the other is about the function----“main”.

Now the question is how to judge which function declaration is about the main function?

In Decl.h, FunctionDecl class:
/// \brief Determines whether this function is “main”, which is the
/// entry point into an executable program.
bool isMain() const;