[throw expression specification] Several questions

[RexJaeschke]

Issue 1: Grammar Question #1

The proposal I started with contained the following grammar:

null_coalescing_expression
    : throw_expression
    ;

Now the existing grammar for null_coalescing_expression is

null_coalescing_expression
    : conditional_or_expression
    | conditional_or_expression '??' null_coalescing_expression
    ;

So, I'm thinking the new grammar should be these two combined, as follows:

null_coalescing_expression
    : conditional_or_expression
    | conditional_or_expression '??' null_coalescing_expression
    | throw_expression
    ;

Is that correct?

Issue 2: Grammar Question #2

Given the final grammar in the previous issue, is the production null_coalescing_expression the only place that refers to the new production, "throw_expression"? Basically, I'm trying to figure out the precedence of this new throw-expression operator.

Issue 3: Result type of ?: operator

The initial proposal stated that

A throw expression shall only occur in the following syntactic contexts:

• As the second or third operand of a ternary conditional operator (?:).
• ...

I think that bullet should be

• As the second or third operand of a ternary conditional operator (?:), but not both.

because if in e1 ? e2 : e3, both e2 and e3 are throw expressions, they have no common type, and the compiler reports, "Error CS0173 Type of conditional expression cannot be determined because there is no implicit conversion between '<throw expression>' and '<throw expression>'.

Am I correct?