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Add example for unreachable code #1012

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Nov 29, 2023
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Add example for unreachable code #1012

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Add example for unreachable code
BillWagner Nov 24, 2023
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BillWagner Nov 27, 2023
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13 changes: 13 additions & 0 deletions standard/variables.md
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Expand Up @@ -343,6 +343,19 @@ The definite-assignment state of *v* on the control flow transfer to a reachable
- If *v* is a pattern variable declared in the *switch_label*: “definitely assigned”.
- Otherwise, the state of *v* is the same as the stat of *v* after *expr*.

> *Example*: The third rule eliminates the need for the compiler to issue an error if an unassigned variable is accessed in unreachable code. The state of *b* is "definitely assigned" in the unreachable switch label `case 2 when b`.
>
> ```csharp
> bool b;
> switch (1)
> {
> case 2 when b: // b is definitely assigned here.
> break;
> }
> ```
>
> *end example*

A consequence of these rules is that a pattern variable declared in a *switch_label* will be “not definitely assigned” in the statements of its switch section if it is not the only reachable switch label in its section.

> *Example*:
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