mirtypes: properly translate recursive imported types #1642
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In the MIR type IR, imported types use a dedicated type kind
(`tkImported`), which has the "to be treated as" type as the element/
base.
Due to unconditionally updating the `PType`->MIR mapping when
translating `importc`ed object types meant that usages of the imported
types within its own body (via a pointer/ref indirection) used the
`tkStruct` symbol, not the `tkImported` symbol.
```nim
type Foreign {.importc: "...".} = object
field: ptr Foreign
# ^^ the field had type `(tkPtr (tkStruct ...))`,
# not `(tkPtr (tkImported ...))`
```
To fix this, `handleImported` now adds a symbol and registers a
mapping right away, with creation of a MIR type symbol for the
"internal" type of `importc`ed types leaving the mapping as is.
zerbina
added
bug
Clyybber
approved these changes
Oct 12, 2025
saem
approved these changes
Oct 13, 2025
|
/merge |
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Merge requested by: @saem Contents after the first section break of the PR description has been removed and preserved below:
|
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Summary
Fix an internal issue with MIR type translation of recursive
imported types.
Details
In the MIR type IR, imported types use a dedicated type kind
(
tkImported), which has the "to be treated as" type as the element/base.
Due to unconditionally updating the
PType->MIR mapping whentranslating
importced object types, usages of the imported typeswithin their own body (via a pointer/ref indirection) used the
tkStructsymbol, not thetkImportedsymbol.This led to internal type mismatches between the actual and computed
type of MIR access expression, but since the type of access expressions
is never recomputed at the moment, the bug had no user-facing effect.
To fix the bug,
handleImportednow adds a symbol and registers amapping right away, with creation of a MIR type symbol for the
"internal" type of
importced types leaving the mapping as is.