Auto Return type deduced caused error when returnStmt contains function itself

[Flbven]

Code:
example1:

// calculate n!
constexpr auto foo(int n) {
	if(n <= 1)
	  return 1;
	return n * foo(n-1);
}

void bar() {
	int k = foo(4);  // get 12 here, it should be 24
}

example2:

constexpr auto foo(int n) {
	if(n <= 1)
	  return 1;
        int v = foo(n-1);
	return n * v;
}

void bar() {
	int k = foo(4);  // get 24 here, correct
}

for the example1's code, printing function foo's binding in ASTPrinter(some changes in print())，i got this for return n * foo(n-1):

CPPASTReturnStatement@885851948<line:4>
        CPPASTBinaryExpression@2048834776 type:Attempt to use symbol failed: foo op:1
          CPPASTIdExpression@245475541 type:int
            CPPASTName@22429093 n   int null            CPPParameter  CPPBasicType
          CPPASTFunctionCallExpression@733957003 type:Attempt to use symbol failed: foo
            CPPASTIdExpression@815992954 type:ProblemType
              CPPASTName@868737467 foo              ProblemBinding Attempt to use symbol failed: foo

CDT can't deduce the right type for the name foo in ReturnStatement，after i debug the code，find out that CDT traverse AST and analyze ReturnStatements to deduce Return Type，at the same time it compute the binding in returnstmt.
So before CDT figure out foo's return type, it already set a ProblemBinding to the name foo in ReturnStatement, when we execute foo(4)，it take out the binding directly and not calculate again because it uses cache.

[jonahgraham]

Thanks for the bug report.

Is this something a user of CDT will see in the Eclipse IDE, or are you using the CDT API to parse and analyse some C++ code.

I would be very happy to review a Pull Request on this.

[Flbven]

Thanks for responding.
i am just using CDT API to parse code, not sure if CDT evalute constepxr function and show the result in UI, didn't use it before.
it needs to change some ASTNode classes's code，because function call may nested by them. working on it