[cfe-dev] Detect if a CXXConstructExpr is implicit

[Loïc Joly via cfe-dev]

In the following code:

https://godbolt.org/z/czpHOf

classA{
public:
    A();
    A(A const&a);
    A(inti);
};

voidf(A a);

voidg() {
   A a;
   f(a); // 1
   f(2); // 2
}

The generated AST contains nodes about object construction that are 
implicit (the copy constructor for 1, the conversion then the copy 
constructor for 2).

     |-CallExpr <line:12:5, col:8> 'void'
     | |-ImplicitCastExpr <col:5> 'void (*)(A)' <FunctionToPointerDecay>
     | | `-DeclRefExpr <col:5> 'void (A)' lvalue Function 0x55c42589b208 
'f' 'void (A)'
     | `-CXXConstructExpr <col:7> 'A' 'void (const A &)'
     |   `-ImplicitCastExpr <col:7> 'const A' lvalue <NoOp>
     |     `-DeclRefExpr <col:7> 'A' lvalue Var 0x55c42589b3c8 'a' 'A'
     `-ExprWithCleanups <line:13:5, col:8> 'void'
       `-CallExpr <col:5, col:8> 'void'
         |-ImplicitCastExpr <col:5> 'void (*)(A)' <FunctionToPointerDecay>
         | `-DeclRefExpr <col:5> 'void (A)' lvalue Function 
0x55c42589b208 'f' 'void (A)'
         `-CXXConstructExpr <col:7> 'A' 'void (const A &)' elidable
           `-MaterializeTemporaryExpr <col:7> 'const A' lvalue
             `-ImplicitCastExpr <col:7> 'const A' <NoOp>
               `-ImplicitCastExpr <col:7> 'A' <ConstructorConversion>
                 `-CXXConstructExpr <col:7> 'A' 'void (int)'
                   `-IntegerLiteral <col:7> 'int' 2

Do you know if there is a way to detect that these constructions are 
implicit (as opposed to constructions written as the type name followed 
by initialization?)

Thank you!

---
Loïc Joly