[move-only] Implement escaping closure semantics part 1 #63783
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…gerly projected box form. This is the first slice of bringing up escaping closure support. The support is based around introducing a new type of SILGen VarLoc: a VarLoc with a box and without a value. Because the VarLoc only has a box, we have to in SILGen always eagerly reproject out the address from the box. The reason why I am doing this is that it makes it easy for the move checker to distinguish in between different accesses to the box that we want to check separately. As such every time that we open the box, we insert a mark_must_check [assignable_but_not_consumable] on that project. If allocbox_to_stack manages to determine that the box can be stack allocated, we eliminate all of the mark_must_check and place a new mark_must_check [consumable_and_assignable] on the alloc_stack. The end result is that we get the old model that we had before and also can support escaping closures.
Some notes: 1. This ensures that if we capture them, we just capture the box by reference. 2. We are still using the old incorrect semantics for captures. I am doing this so I can bring this up in separate easy to understand patches all of which pass all of the moveonly tests. 3. Most of the test edits are due to small differences in error messages in between the object and address checker. 4. I had to add a little support to the move only address checker for a small pattern that doesn't occur with vars but do es occur for lets when we codegen like this, specifically around enums. The pattern is we perform a load_borrow and then copy_value and then use the result of the copy_value. Rather than fight SILGen pattern I introduced a small canonicalization into the address checker which transforms that pattern into a load [copy] + begin_borrow to restore the codegen to a pattern the checker expects. 5. I left noimplicitcopy alone for now. But we should come back around and fix it in a similar way. I just did not have time to do so.
NOTE: A few of the test patterns need to be made better, but this patch series is large enough, I want to get it into tree and iterate.
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jckarter
reviewed
Feb 20, 2023
jckarter
reviewed
Feb 20, 2023
Thanks to JoeG for seeing this quickly and preventing me from having to track this down!
…escaping closure since we will already emit a more specific capture error.
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Linux failure was unrelated problem in dispatch. |
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Windows failed b/c I left in some optnone by mistake from when I was debugging |
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@swift-ci clean smoke test linux platform |
ludwwwig
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This header was supposed to be deleted by swiftlang#63783.
ludwwwig
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This header was supposed to be deleted by swiftlang#63783.
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This patch series does a bunch of things:
This basically required me to rewrite a large part of SILGen for non copyable types and redesign parts of the checker as well. I also had to do a bunch of work in alloc box to stack to massage its output since it semantically is what controls whether we use non-escaping or escaping semantics when we emit these errors.