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Fix define-instance context bug (1340) #1342

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merged 1 commit into from
Jan 14, 2025
Merged

Fix define-instance context bug (1340) #1342

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48 changes: 25 additions & 23 deletions src/typechecker/define-instance.lisp
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Original file line number Diff line number Diff line change
Expand Up @@ -183,29 +183,31 @@

:for superclass := (tc:apply-substitution instance-subs superclass_)

:for superclass-instance
:= (or (tc:lookup-class-instance
env
superclass
:no-error t)
(tc-error "Instance missing context"
(tc-location (parser:toplevel-define-instance-head-location unparsed-instance)
"No instance for ~S" superclass)))

:for additional-context
:= (tc:apply-substitution
(tc:predicate-match
(tc:apply-substitution instance-subs (tc:ty-class-instance-predicate superclass-instance))
superclass)
(tc:ty-class-instance-constraints superclass-instance))

:do (loop :for pred :in additional-context
:do (unless (tc:entail env context pred)
(tc-error "Instance missing context"
(tc-location (parser:toplevel-define-instance-head-location unparsed-instance)
"No instance for ~S arising from constraints of superclasses ~S"
pred
superclass)))))
:unless (tc:entail env context superclass)

:do (loop :for superclass-instance
:= (or (tc:lookup-class-instance
env
superclass
:no-error t)
(tc-error "Instance missing context"
(tc-location (parser:toplevel-define-instance-head-location unparsed-instance)
"No instance for ~S" superclass)))

:for additional-context
:= (tc:apply-substitution
(tc:predicate-match
(tc:apply-substitution instance-subs (tc:ty-class-instance-predicate superclass-instance))
superclass)
(tc:ty-class-instance-constraints superclass-instance))

:do (loop :for pred :in additional-context
:do (unless (tc:entail env context pred)
(tc-error "Instance missing context"
(tc-location (parser:toplevel-define-instance-head-location unparsed-instance)
"No instance for ~S arising from constraints of superclasses ~S"
pred
superclass))))))

(check-duplicates
(parser:toplevel-define-instance-methods unparsed-instance)
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15 changes: 15 additions & 0 deletions tests/test-files/define-instance.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,21 @@
(define-instance (Eq C)
(define (== _ _) True))

================================================================================
10 Define instance
================================================================================

(package coalton-unit-tests)

;; see issue #1340

(define-type (T :a))
(define-class (P :a))
(define-class (C :a :b))
(define-class ((P :a) (C :b :a) => PC :b :a))
(define-instance (C (T :a) :a))
(define-instance (P :a => PC (T :a) :a))

================================================================================
100 Malformed method definition
================================================================================
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