tmp/tmp680t27_t/{from.md → to.md}
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### Undefined behavior <a id="utility.undefined">[[utility.undefined]]</a>
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``` cpp
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[[noreturn]] void unreachable();
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```
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*Preconditions:* `false` is `true`.
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[*Note 1*: This precondition cannot be satisfied, thus the behavior of
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calling `unreachable` is undefined. — *end note*]
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[*Example 1*:
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``` cpp
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int f(int x) {
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switch (x) {
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case 0:
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case 1:
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return x;
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default:
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std::unreachable();
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}
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}
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int a = f(1); // OK, a has value 1
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int b = f(3); // undefined behavior
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```
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— *end example*]
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``` cpp
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void observable_checkpoint() noexcept;
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```
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*Effects:* Establishes an observable checkpoint [[intro.abstract]].
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