[Typed throws] Make try? and try! into catch nodes #70283
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The ASTScope class hierarchy rooted at ASTScopeImpl is relying entirely on overridden virtual functions and, in some cases, string comparisons on the class name, to provide customization for the various classes. Introduce proper LLVM dynamic casting support to this class hierarchy, eliminating the string comparisons and the manually-specified implementations of `getClassName` (which is now used only for printing). We've been meaning to do this for years, but today I got angry enough.
Replace a number of virtual query functions like `getDeclIfAny`, which had to be overridden at various points in the hierarchy, with simpler implementations based on the scope kind and `dyn_cast`. Macro-metaprogram whether each scope node is associated with a particular declaration/statement/expression/attribute so these implementations can be efficiently macro-metaprogrammed.
The subclasses of `GenericTypeOrExtensionScope` are customized by a `Portion` mix-in class that effectively makes each into several different scope nodes: one for the "whole decl", one for the where clause, one for the body. Re-introduce the customized `getClassName()` operation so we get the nicer debugging dumps.
The implementation of "lookup the catch node" is scattered throughout various `ASTScopeImpl` subclasses. Remove that, and instead centralize the code to find the innermost catch scope.
... it's just a `dyn_cast` now.
We only used this in one place, and then immediately filtered down to a `CustomAttr`. Just use `dyn_cast` in the obvious way and remove this function.
Both `try?` and `try!` are catch nodes, because they catch an error thrown in their subexpression and handle it. Introduce an ASTScope for all `try/try?/try1` expressions so we can find them, and model them as catch nodes. Fixes rdar://119216455.
An attempted SILGen optimization caused assertions and SIL verification errors. Always convert the error appropriately. Fixes rdar://119214492.
DougGregor
requested review from
hborla,
xedin and
slavapestov
as code owners
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@swift-ci please smoke test |
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@swift-ci please smoke test macOS |
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Both
try?andtry!are catch nodes, because they catch an errorthrown in their subexpression and handle it. Introduce an ASTScope for
all
try/try?/try1expressions so we can find them, and model them ascatch nodes.
While here, remove a premature SILGen optimization that ends up
emitting bad SIL.
Fixes rdar://119216455 & rdar://119214492.