[Macros] Teach name lookup in macro expansions to look in expansion context #61845
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Introduce a new source file kind to describe source files for macro expansions, and include the macro expression that they expand. This establishes a "parent" relationship Also track every kind of auxiliary source file---whether for macro expansions or other reasons---that is introduced into a module, adding an operation that allows us to find the source file that contains a given source location.
…tions. In the Swift grammar, the top-level of a source file is a mix of three different kinds of "items": declarations, statements, and expressions. However, the existing parser forces all of these into declarations at parse time, wrapping statements and expressions in TopLevelCodeDecls, so the primary API for getting the top-level entities in source files is based on getting declarations. Start generalizing the representation by storing ASTNode instances at the top level, rather than declaration pointers, updating many (but not all!) uses of this API. The walk over declarations is a (cached) filter to pick out all of the declarations. Existing parsed files are unaffected (the parser still creates top-level code declarations), but the new "macro expansion" source file kind skips creating top-level code declarations so we get the pure parse tree. Additionally, some generalized clients (like ASTScope lookup) will now look at the list of items, so they'll be able to walk into statements and expressions without the intervening TopLevelCodeDecl. Over time, I'd like to phase out `getTopLevelDecls()` entirely, relying on the new `getTopLevelItems()` for parsed content. We can introduce TopLevelCodeDecls more lazily for semantic walks.
…ontext Teach ASTScope how to reason about macro expansions. When we create an ASTScope for a source file that represents a macro expansion, its parent scope node is the macro expansion itself. When performing unqualified lookup (of any form), find the starting source file based on the location, not on the source file provided---this ensures that we start lookups within the macro expansion (for example). The effect of this is to enable macro expansions to work in nested contexts, where they refer to names in the scope in which the macro is expanded. This is decidedly unhiegenic, but it fits with our syntactic model.
DougGregor
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ahoppen,
bnbarham,
CodaFi and
rintaro
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swiftlang/swift-package-manager#5858 @swift-ci please smoke test |
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See swiftlang/swift#61662 and swiftlang/swift#61845. (cherry picked from commit 2c09962)
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Introduce a new source file kind to describe source files for macro
expansions, and include the macro expression that they expand. This
establishes a "parent" relationship so we can track source locations
within a macro expansion back to the place in the AST where the
macro expansion was triggered.
Teach ASTScope how to reason about macro expansions. When we create an
ASTScope for a source file that represents a macro expansion, its
parent scope node is the macro expansion itself. When performing
unqualified lookup (of any form), find the starting source file based
on the location, not on the source file provided---this ensures that
we start lookups within the macro expansion (for example).
The effect of this is to enable macro expansions to work in nested
contexts, where they refer to names in the scope in which the macro is
expanded.
This is decidedly unhiegenic, but it fits with our syntactic model.