Change inference.md as needed for 4718 - #4724
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lrhn
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| **definite completion** analysis specified elsewhere. | ||
| - Let `T` be `Null` if any control path reaches the end of the block | ||
| without exiting the block, as computed by the **definite completion** | ||
| analysis specified elsewhere. |
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(You can probably guess I'd prefer that case to have type void 😁 . Not returning something is not the same as returning null. It's the same as not returning anything useful. Alas, not where we are today.)
lrhn
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Jul 10, 2026
| block without reaching the end of the block, as computed by the | ||
| **definite completion** analysis specified elsewhere. | ||
| - Let `T` be `Null` if any control path reaches the end of the block | ||
| without exiting the block, as computed by the **definite completion** |
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Is "without exiting the block" redundant? Or just confusing?
If control reaches the end, then it definitely didn't exit before that.
On the other hand, it will exit as the very next thing, so does it really "reach then end of the block without exiting" when it "reaches the block and exits"?
lrhn
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Jul 10, 2026
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This PR changes the specification of type inference such that the inferred return type of a generator function literal does not include a spurious
Null, which is otherwise added in the case where the end of the body of the function literal can be reached. For example,() sync* {}has inferred return typeIterable<Null>, but with this change it will beIterable<Never>, as it should be.