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| .. _fls_G64vdcIyB2Is: | ||
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| Closure capture precision |
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You may want to rename this section "Capture precision", similar to the Reference, and make it subheading of 6.22. Capturing.
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heh, I missed that 6.22 even existed :hide:
| Closure capture precision | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
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| :dp:`fls_rdDT7jsaOMbs` |
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This paragraph should be swapped with :dp:fls_j9WyKVyOLFon. The FLS avoids forward referencing as much as possible. Here you are using the term "place projection", but you have not defined it yet.
| A :dt:`place projection` is a :t:`field access expression`, tuple :t:`field access expression`, :t:`dereference`, array or slice :t:`index expression`, or :t:`pattern` destructuring applied to a variable. | ||
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| :dp:`fls_TbfUxVf8PKPs` | ||
| The closure :t:`[borrow]s` or :t:`moves <by move>` the :t:`capture path`, which may be truncated based on these rules: |
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How about
A :t:closure expression :t:[borrow]s or :t:moves <by move> the :t:capture path, as follows:
| The closure :t:`[borrow]s` or :t:`moves <by move>` the :t:`capture path`, which may be truncated based on these rules: | ||
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| - :dp:`fls_4TESOxGpEY2h` | ||
| When a :t:`capture path` and one of the ancestors of that path are both captured by a closure, the ancestor path is captured with the highest capture mode among the two captures, using the strict weak ordering: :t:`immutable borrow` < :t:`unique immutable borrow` < :t:`mutable borrow` < :t:`move <by move>`. |
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It is unclear what an "ancestor" is. Be careful when using the term "path", because we also have these paths. What the Reference describes is already documented in 6.22:12 The capture mode ....
I would rephrase the paragraph as follows (note that it is part of a list!):
- When a :t:
capture pathand an ancestor :t:capture pathand both :t:captured, the ancestor :t:capture pathis :t:capturedwith the highest :t:capture modeamong the two :t:[capture path]s.
Note that I intentionally dropped "by a closure" because a "capturing expression" is either an async block expression or a closure expression, and I suspect that these rules do apply when the context is an async block expression.
I also dropped the ordering because it is already documented by "capture mode". On a side note, perhaps 6.22:14 should be changed to "1. By immutable reference capture. (lowest precedence)" and 6:22:17 to "4. By value capture. (highest precedence)", or just use a small table similar to expression precedence.
| The :t:`capture path` is truncated at the rightmost :t:`dereference` in the capture path if the dereference is applied to a :t:`shared reference`. | ||
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| :dp:`fls_v8IFXHJnXhez` | ||
| A :t:`place` is not captured when an :t:`underscore expression` is used to bind it. |
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The Reference is unclear what "place" refers to - is it a "place projection", a "place expression", or a "place". I suspect the former, but this needs confirmation. Once that is cleared up, there are options to refactor some of the rules below.
Co-authored-by: Hristian Kirtchev <60669983+kirtchev-adacore@users.noreply.github.com>
Co-authored-by: Hristian Kirtchev <60669983+kirtchev-adacore@users.noreply.github.com>
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all addressed but #698 (comment) |
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This captures some gaps FLS has compared to Reference, and the content is adjusted from Closure capture precision section.