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Merged
hvitved merged 3 commits into from
Oct 9, 2026
Merged

Type inference: Improve base type matching #22761

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72a00e3
Unified: More type inference tests
hvitved Oct 6, 2026
70e4424
Unified: Type inference for empty array literals
hvitved Oct 7, 2026
468caa3
Type inference: Improve base type matching
hvitved Oct 6, 2026
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Type inference: Improve base type matching
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@hvitved
hvitved committed Oct 7, 2026
commit 468caa3ba37def5992e656b62fa187fc07e61022
84 changes: 84 additions & 0 deletions shared/typeinference/codeql/typeinference/internal/TypeInference.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -1504,6 +1504,80 @@ module Make1<LocationSig Location, InputSig1<Location> Input1> {
hasNotTypeArgument(a, target, tp)
)
}

predicate baseTypeMatchAtTypeParameter(
Access a, AccessEnvironment e, AccessPosition apos, Declaration target, TypeParameter tp,
TypePath prefix, TypePath requiredPrefix
) {
exists(
TypePath pathToTypeParamInConstraint, TypePath pathToTp, TypePath pathToTypeParamInSub
|
argRootTypeSatisfiesTargetTypeCand(_, target, pragma[only_bind_into](apos), tp, pathToTp) and
SatisfiesParameterConstraint::satisfiesConstraintAtTypeParameter(MkRelevantAccess(a,
pragma[only_bind_into](apos), e),
MkRelevantTarget(target, pragma[only_bind_into](apos)), pathToTypeParamInConstraint,
pathToTypeParamInSub) and
hasNotTypeArgument(a, target, tp)
|
/*
* Example:
*
* ```swift
* class Base<B> {
* init(_ value: B) {}
* }
*
* class Derived<D>: Base<[D]> {
* init(_ value: D) { super.init([value]) }
* }
*
* func foo<T>(_ value: T, _ base: Base<T>) { }
*
* foo([2], Derived(<unknown>))
* ```
*
* - tp = T (bound by `foo`)
* - prefix = pathToTypeParamInSub = "D"
* - requiredPrefix = "Element"
* - pathToTypeParamInConstraint = "B.Element"
* - pathToTp = "B"
*/

pathToTypeParamInConstraint = pathToTp.appendInverse(requiredPrefix) and
prefix = pathToTypeParamInSub
or
/*
* Example:
*
* ```swift
* class Base<B> {
* init(_ value: B) {}
* }
*
* class Derived<D>: Base<D> {
* override init(_ value: D) { super.init(value) }
* }
*
* func foo<T>(_ value: T, _ base: Base<T?>) {}
*
* foo(2, Derived(Optional.none))
* ```
*
* - tp = T (bound by `foo`)
* - prefix = "D.Wrapped"
* - pathToTypeParamInSub = "D"
* - requiredPrefix = ""
* - pathToTypeParamInConstraint = "B"
* - pathToTp = "B.Wrapped"
*/

exists(TypePath path0 |
pathToTp = pathToTypeParamInConstraint.appendInverse(path0) and
prefix = pathToTypeParamInSub.append(path0) and
requiredPrefix = TypePath::nil()
)
)
}
}

private module AccessConstraint {
Expand Down Expand Up @@ -1745,6 +1819,16 @@ module Make1<LocationSig Location, InputSig1<Location> Input1> {
)
)
or
exists(
Declaration target, TypePath prefix, TypePath requiredPrefix, TypePath suffix,
TypeParameter tp
|
AccessBaseType::baseTypeMatchAtTypeParameter(a, e, apos, target, tp, prefix,
requiredPrefix) and
typeMatch(a, e, target, requiredPrefix.appendInverse(suffix), result, tp) and
path = prefix.append(suffix)
)
or
exists(
Declaration target, TypePath prefix, TypeMention constraint,
TypePath pathToTypeParamInConstraint, TypePath pathToTypeParamInSub
Expand Down
6 changes: 3 additions & 3 deletions unified/ql/test/library-tests/type-inference/generics.swift
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Expand Up @@ -204,15 +204,15 @@ func testDerived() {

let x = foo(false, [2], DerivedDerived([])) // $ target=foo target=DerivedDerived.init type=x@DerivedDerived<D>:Int

foo2(false, [2], DerivedDerived([])) // $ target=foo2 target=DerivedDerived.init $ MISSING: type=DerivedDerived(...)@DerivedDerived<D>:Int
foo2(false, [2], DerivedDerived([])) // $ target=foo2 target=DerivedDerived.init type=DerivedDerived(...)@DerivedDerived<D>:Int

let y = bar(false, 2, DerivedDerived([])) // $ type=y@DerivedDerived<D>:Int target=bar target=DerivedDerived.init

bar2(false, 2, DerivedDerived([])) // $ target=bar2 target=DerivedDerived.init $ MISSING: type=DerivedDerived(...)@DerivedDerived<D>:Int
bar2(false, 2, DerivedDerived([])) // $ target=bar2 target=DerivedDerived.init type=DerivedDerived(...)@DerivedDerived<D>:Int

let w = baz(false, 2, Derived(Optional.none)) // $ type=w@Derived<T1>.Optional<Wrapped>:Int target=baz target=Derived.init field=Optional.none

baz2(false, 2, Derived(Optional.none)) // $ target=baz2 target=Derived.init field=Optional.none $ MISSING: type=Derived(...)@Derived<T1>.Optional<Wrapped>:Int
baz2(false, 2, Derived(Optional.none)) // $ target=baz2 target=Derived.init field=Optional.none type=Derived(...)@Derived<T1>.Optional<Wrapped>:Int
}

// --- Generics and protocols ---
Expand Down
6 changes: 6 additions & 0 deletions unified/ql/test/library-tests/type-inference/type-inference.expected
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Original file line number Diff line number Diff line change
Expand Up @@ -1429,7 +1429,9 @@ inferType
| generics.swift:207:15:207:17 | ArrayLiteral | Element | {EXTERNAL LOCATION} | Int |
| generics.swift:207:16:207:16 | 2 | | {EXTERNAL LOCATION} | Int |
| generics.swift:207:20:207:37 | DerivedDerived(...) | | generics.swift:164:1:172:1 | DerivedDerived |
| generics.swift:207:20:207:37 | DerivedDerived(...) | D | {EXTERNAL LOCATION} | Int |
| generics.swift:207:35:207:36 | ArrayLiteral | | {EXTERNAL LOCATION} | Array |
| generics.swift:207:35:207:36 | ArrayLiteral | Element | {EXTERNAL LOCATION} | Int |
| generics.swift:209:7:209:7 | y | | generics.swift:164:1:172:1 | DerivedDerived |
| generics.swift:209:7:209:7 | y | D | {EXTERNAL LOCATION} | Int |
| generics.swift:209:11:209:43 | bar(...) | | generics.swift:164:1:172:1 | DerivedDerived |
Expand All @@ -1443,7 +1445,9 @@ inferType
| generics.swift:211:8:211:12 | false | | {EXTERNAL LOCATION} | Bool |
| generics.swift:211:15:211:15 | 2 | | {EXTERNAL LOCATION} | Int |
| generics.swift:211:18:211:35 | DerivedDerived(...) | | generics.swift:164:1:172:1 | DerivedDerived |
| generics.swift:211:18:211:35 | DerivedDerived(...) | D | {EXTERNAL LOCATION} | Int |
| generics.swift:211:33:211:34 | ArrayLiteral | | {EXTERNAL LOCATION} | Array |
| generics.swift:211:33:211:34 | ArrayLiteral | Element | {EXTERNAL LOCATION} | Int |
| generics.swift:213:7:213:7 | w | | generics.swift:154:1:162:1 | Derived |
| generics.swift:213:7:213:7 | w | T1 | {EXTERNAL LOCATION} | Optional |
| generics.swift:213:7:213:7 | w | T1.Wrapped | {EXTERNAL LOCATION} | Int |
Expand All @@ -1463,7 +1467,9 @@ inferType
| generics.swift:215:15:215:15 | 2 | | {EXTERNAL LOCATION} | Int |
| generics.swift:215:18:215:39 | Derived(...) | | generics.swift:154:1:162:1 | Derived |
| generics.swift:215:18:215:39 | Derived(...) | T1 | {EXTERNAL LOCATION} | Optional |
| generics.swift:215:18:215:39 | Derived(...) | T1.Wrapped | {EXTERNAL LOCATION} | Int |
| generics.swift:215:26:215:38 | ... .none | | {EXTERNAL LOCATION} | Optional |
| generics.swift:215:26:215:38 | ... .none | Wrapped | {EXTERNAL LOCATION} | Int |
| generics.swift:227:22:229:3 | Block | | generics.swift:220:1:224:1 | MyProtocol2 |
| generics.swift:228:12:228:15 | self | | generics.swift:220:1:224:1 | MyProtocol2 |
| generics.swift:233:7:233:11 | value | | generics.swift:232:15:232:15 | T |
Expand Down
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