ISyntaxCheck: build ATF equivalences from canonical qualified tycons#1051
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ISyntaxCheck: build ATF equivalences from canonical qualified tycons#1051nanavati wants to merge 1 commit into
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ISyntaxCheck.atfEqsFromDict built associated-type-function tycons from raw getAllTypes enumeration keys. The symtab type map holds one entry per visible alias of a type -- for the current package's own decls both the qualified name and the bare one, sharing a single TypeInfo -- so each dict addition also manufactured a duplicate equivalence keyed by an unqualified ATF tycon (first seen: Rep alongside Prelude.Rep, during the Prelude's own compile). Every other ITCon producer feeds from CTypes canonicalized by MakeSymTab.trCType', which substitutes the qualified ti_qual_id, so real ATF applications always carry qualified tycon Ids. The unqualified duplicates could never match them in eqType: they sat in the equivalence classes as silently inert entries. Build the ATF tycon from ti_qual_id and keep one entry per ATF by matching only the canonical alias (atfId == qatfId). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Vjo7EmAfHvZTWPDJ923FVz
This was referenced Jul 15, 2026
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What
ISyntaxCheck.atfEqsFromDictbuilds associated-type-function tycons from raw symtabenumeration keys. The symtab type map holds one entry per visible alias of a type — for
the current package's own decls, both the qualified name and the bare one, sharing a
single
TypeInfo— so each dict addition also produced an equivalence keyed by anunqualified ATF tycon (first seen:
Repof Prelude'sGeneric, during the Prelude'sown compile).
Build the ATF tycon from
ti_qual_idand keep one entry per ATF by matching only thecanonical alias.
Why
Every other ITCon producer feeds from CTypes canonicalized by
MakeSymTab.trCType',which substitutes the qualified
ti_qual_id; this was the one site synthesizing tyconsoutside that layer. A bare-named equivalence key is latently unsound —
qualEqlets anunqualified id match any package's same-named ATF — and it breaks the
one-tycon-per-qualified-name invariant that the IType interning stack (#1048) turns into
a hard assertion. With the origin fixed, #1048 retires its tolerance paths for
unqualified tycons.
Validation
Found by the interning stack's checked build (
-trace-itype-intern, since removed);that checked library build is green with this fix, and the full stack records
fullparallel 20281 passes / 0 unexpected failures / 134 expected failures. Standalone on
main the change is output-neutral: the equivalence set merely loses its
duplicate/unqualified keys.
Stack
Standalone on main. First of four independent fixes (#1051 (this), #1052 listcons SDataCon
sort, #1053 (S0015 field position), #1054 (CIclass sort members)) that the reworked #1048
(IType interning) stacks on, below #1045 ← #1046 ← #1047.