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Infer fixed-size tuples from infer type parameters with extends clauses at variadic positions #51157

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Merged
merged 9 commits into from
Jan 3, 2023
Merged

Infer fixed-size tuples from infer type parameters with extends clauses at variadic positions #51157

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399528b
Infer fixed-size tuples from infer type parameters with extends claus…
Andarist Oct 11, 2022
3bdd860
Improve the fix to handle tuples with leading variadic elements
Andarist Oct 12, 2022
f6840d5
Merge branch 'main' into fix/51138
Andarist Nov 7, 2022
52c931c
Merge remote-tracking branch 'origin/main' into fix/51138
Andarist Nov 25, 2022
f92c184
Fixed indentation
Andarist Nov 25, 2022
b126b9d
Merge remote-tracking branch 'origin/main' into fix/51138
Andarist Dec 25, 2022
8a60a28
Infer rest element following a variadic element with a fixed-size con…
Andarist Dec 26, 2022
aef842f
Infer rest element preceding a variadic element with a fixed-size con…
Andarist Dec 26, 2022
f7478bf
Rewrite the test to avoid accidental union reductions
Andarist Dec 26, 2022
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43 changes: 36 additions & 7 deletions src/compiler/checker.ts
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Expand Up @@ -24307,13 +24307,42 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
}
else {
const middleLength = targetArity - startLength - endLength;
if (middleLength === 2 && elementFlags[startLength] & elementFlags[startLength + 1] & ElementFlags.Variadic && isTupleType(source)) {
// Middle of target is [...T, ...U] and source is tuple type
const targetInfo = getInferenceInfoForType(elementTypes[startLength]);
if (targetInfo && targetInfo.impliedArity !== undefined) {
// Infer slices from source based on implied arity of T.
inferFromTypes(sliceTupleType(source, startLength, endLength + sourceArity - targetInfo.impliedArity), elementTypes[startLength]);
inferFromTypes(sliceTupleType(source, startLength + targetInfo.impliedArity, endLength), elementTypes[startLength + 1]);
if (middleLength === 2) {
if (elementFlags[startLength] & elementFlags[startLength + 1] & ElementFlags.Variadic && isTupleType(source)) {
// Middle of target is [...T, ...U] and source is tuple type
const targetInfo = getInferenceInfoForType(elementTypes[startLength]);
if (targetInfo && targetInfo.impliedArity !== undefined) {
// Infer slices from source based on implied arity of T.
inferFromTypes(sliceTupleType(source, startLength, endLength + sourceArity - targetInfo.impliedArity), elementTypes[startLength]);
inferFromTypes(sliceTupleType(source, startLength + targetInfo.impliedArity, endLength), elementTypes[startLength + 1]);
}
}
else if (elementFlags[startLength] & ElementFlags.Variadic && elementFlags[startLength + 1] & ElementFlags.Rest) {
// Middle of target is [...T, ...rest] and source is tuple type
// if T is constrained by a fixed-size tuple we might be able to use its arity to infer T
const param = getInferenceInfoForType(elementTypes[startLength])?.typeParameter;
const constraint = param && getBaseConstraintOfType(param);
if (constraint && isTupleType(constraint) && !constraint.target.hasRestElement) {
const impliedArity = constraint.target.fixedLength;
inferFromTypes(sliceTupleType(source, startLength, sourceArity - (startLength + impliedArity)), elementTypes[startLength]);
inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength + impliedArity, endLength)!, elementTypes[startLength + 1]);
}
}
else if (elementFlags[startLength] & ElementFlags.Rest && elementFlags[startLength + 1] & ElementFlags.Variadic && isTupleType(source)) {
// Middle of target is [...rest, ...T] and source is tuple type
// if T is constrained by a fixed-size tuple we might be able to use its arity to infer T
const param = getInferenceInfoForType(elementTypes[startLength + 1])?.typeParameter;
const constraint = param && getBaseConstraintOfType(param);
if (constraint && isTupleType(constraint) && !constraint.target.hasRestElement) {
const impliedArity = constraint.target.fixedLength;
const endIndex = sourceArity - getEndElementCount(target.target, ElementFlags.Fixed);
const startIndex = endIndex - impliedArity;
const trailingSlice = createTupleType(getTypeArguments(source).slice(startIndex, endIndex), source.target.elementFlags.slice(startIndex, endIndex),
/*readonly*/ false, source.target.labeledElementDeclarations && source.target.labeledElementDeclarations.slice(startIndex, endIndex));

inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength, endLength + impliedArity)!, elementTypes[startLength]);
inferFromTypes(trailingSlice, elementTypes[startLength + 1]);
}
}
}
else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Variadic) {
Expand Down
160 changes: 160 additions & 0 deletions tests/baselines/reference/inferTypesWithFixedTupleExtendsAtVariadicPosition.symbols
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=== tests/cases/compiler/inferTypesWithFixedTupleExtendsAtVariadicPosition.ts ===
// repro #51138

type SubTup2FixedLength<T extends unknown[]> = T extends [
>SubTup2FixedLength : Symbol(SubTup2FixedLength, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 0, 0))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 2, 24))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 2, 24))

...infer B extends [any, any],
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 3, 10))

any
]
? B
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 3, 10))

: never;

type SubTup2FixedLengthTest = SubTup2FixedLength<[a: 0, b: 1, c: 2]>;
>SubTup2FixedLengthTest : Symbol(SubTup2FixedLengthTest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 7, 10))
>SubTup2FixedLength : Symbol(SubTup2FixedLength, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 0, 0))

type SubTup2Variadic<T extends unknown[]> = T extends [
>SubTup2Variadic : Symbol(SubTup2Variadic, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 9, 69))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 11, 21))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 11, 21))

...infer B extends [any, any],
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 12, 10))

...any
]
? B
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 12, 10))

: never;

type SubTup2VariadicTest = SubTup2Variadic<[a: 0, b: 1, ...c: 2[]]>;
>SubTup2VariadicTest : Symbol(SubTup2VariadicTest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 16, 10))
>SubTup2Variadic : Symbol(SubTup2Variadic, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 9, 69))

type SubTup2VariadicTest2 = SubTup2Variadic<[a: 0, b: 1, c: 2, ...d: 3[]]>;
>SubTup2VariadicTest2 : Symbol(SubTup2VariadicTest2, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 18, 68))
>SubTup2Variadic : Symbol(SubTup2Variadic, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 9, 69))

type SubTup2VariadicAndRest<T extends unknown[]> = T extends [
>SubTup2VariadicAndRest : Symbol(SubTup2VariadicAndRest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 19, 75))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 21, 28))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 21, 28))

...infer B extends [any, any],
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 22, 12))

...(infer C)[]
>C : Symbol(C, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 23, 13))

]
? [...B, ...[C]]
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 22, 12))
>C : Symbol(C, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 23, 13))

: never;

type SubTup2VariadicAndRestTest = SubTup2VariadicAndRest<[a: 0, b: 1, ...c: 2[]]>;
>SubTup2VariadicAndRestTest : Symbol(SubTup2VariadicAndRestTest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 26, 12))
>SubTup2VariadicAndRest : Symbol(SubTup2VariadicAndRest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 19, 75))

type SubTup2TrailingVariadic<T extends unknown[]> = T extends [
>SubTup2TrailingVariadic : Symbol(SubTup2TrailingVariadic, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 28, 82))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 30, 29))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 30, 29))

...any,
...infer B extends [any, any],
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 32, 10))

]
? B
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 32, 10))

: never;

type SubTup2TrailingVariadicTest = SubTup2TrailingVariadic<[...a: 0[], b: 1, c: 2]>;
>SubTup2TrailingVariadicTest : Symbol(SubTup2TrailingVariadicTest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 35, 10))
>SubTup2TrailingVariadic : Symbol(SubTup2TrailingVariadic, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 28, 82))

type SubTup2TrailingVariadicTest2 = SubTup2TrailingVariadic<[...a: 0[], b: 1, c: 2, d: 3]>;
>SubTup2TrailingVariadicTest2 : Symbol(SubTup2TrailingVariadicTest2, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 37, 84))
>SubTup2TrailingVariadic : Symbol(SubTup2TrailingVariadic, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 28, 82))

type SubTup2RestAndTrailingVariadic2<T extends unknown[]> = T extends [
>SubTup2RestAndTrailingVariadic2 : Symbol(SubTup2RestAndTrailingVariadic2, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 38, 91))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 40, 37))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 40, 37))

...(infer C)[],
>C : Symbol(C, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 41, 13))

...infer B extends [any, any],
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 42, 12))

]
? [C, ...B]
>C : Symbol(C, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 41, 13))
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 42, 12))

: never;

type SubTup2RestAndTrailingVariadic2Test = SubTup2RestAndTrailingVariadic2<[...a: 0[], b: 1, c: 2]>;
>SubTup2RestAndTrailingVariadic2Test : Symbol(SubTup2RestAndTrailingVariadic2Test, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 45, 12))
>SubTup2RestAndTrailingVariadic2 : Symbol(SubTup2RestAndTrailingVariadic2, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 38, 91))

type SubTup2VariadicWithLeadingFixedElements<T extends unknown[]> = T extends [
>SubTup2VariadicWithLeadingFixedElements : Symbol(SubTup2VariadicWithLeadingFixedElements, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 47, 100))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 49, 45))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 49, 45))

any,
...infer B extends [any, any],
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 51, 10))

...any
]
? B
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 51, 10))

: never;

type SubTup2VariadicWithLeadingFixedElementsTest = SubTup2VariadicWithLeadingFixedElements<[a: 0, b: 1, c: 2, ...d: 3[]]>;
>SubTup2VariadicWithLeadingFixedElementsTest : Symbol(SubTup2VariadicWithLeadingFixedElementsTest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 55, 10))
>SubTup2VariadicWithLeadingFixedElements : Symbol(SubTup2VariadicWithLeadingFixedElements, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 47, 100))

type SubTup2VariadicWithLeadingFixedElementsTest2 = SubTup2VariadicWithLeadingFixedElements<[a: 0, b: 1, c: 2, d: 3, ...e: 4[]]>;
>SubTup2VariadicWithLeadingFixedElementsTest2 : Symbol(SubTup2VariadicWithLeadingFixedElementsTest2, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 57, 122))
>SubTup2VariadicWithLeadingFixedElements : Symbol(SubTup2VariadicWithLeadingFixedElements, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 47, 100))

type SubTup2TrailingVariadicWithTrailingFixedElements<T extends unknown[]> = T extends [
>SubTup2TrailingVariadicWithTrailingFixedElements : Symbol(SubTup2TrailingVariadicWithTrailingFixedElements, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 58, 129))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 60, 54))
>T : Symbol(T, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 60, 54))

...any,
...infer B extends [any, any],
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 62, 10))

any,
]
? B
>B : Symbol(B, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 62, 10))

: never;

type SubTup2TrailingVariadicWithTrailingFixedElementsTest = SubTup2TrailingVariadicWithTrailingFixedElements<[...a: 0[], b: 1, c: 2, d: 3]>;
>SubTup2TrailingVariadicWithTrailingFixedElementsTest : Symbol(SubTup2TrailingVariadicWithTrailingFixedElementsTest, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 66, 10))
>SubTup2TrailingVariadicWithTrailingFixedElements : Symbol(SubTup2TrailingVariadicWithTrailingFixedElements, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 58, 129))

type SubTup2TrailingVariadicWithTrailingFixedElementsTest2 = SubTup2TrailingVariadicWithTrailingFixedElements<[...a: 0[], b: 1, c: 2, d: 3, e: 4]>;
>SubTup2TrailingVariadicWithTrailingFixedElementsTest2 : Symbol(SubTup2TrailingVariadicWithTrailingFixedElementsTest2, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 68, 140))
>SubTup2TrailingVariadicWithTrailingFixedElements : Symbol(SubTup2TrailingVariadicWithTrailingFixedElements, Decl(inferTypesWithFixedTupleExtendsAtVariadicPosition.ts, 58, 129))

101 changes: 101 additions & 0 deletions tests/baselines/reference/inferTypesWithFixedTupleExtendsAtVariadicPosition.types
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=== tests/cases/compiler/inferTypesWithFixedTupleExtendsAtVariadicPosition.ts ===
// repro #51138

type SubTup2FixedLength<T extends unknown[]> = T extends [
>SubTup2FixedLength : SubTup2FixedLength<T>

...infer B extends [any, any],
any
]
? B
: never;

type SubTup2FixedLengthTest = SubTup2FixedLength<[a: 0, b: 1, c: 2]>;
>SubTup2FixedLengthTest : [a: 0, b: 1]

type SubTup2Variadic<T extends unknown[]> = T extends [
>SubTup2Variadic : SubTup2Variadic<T>

...infer B extends [any, any],
...any
]
? B
: never;

type SubTup2VariadicTest = SubTup2Variadic<[a: 0, b: 1, ...c: 2[]]>;
>SubTup2VariadicTest : [a: 0, b: 1]

type SubTup2VariadicTest2 = SubTup2Variadic<[a: 0, b: 1, c: 2, ...d: 3[]]>;
>SubTup2VariadicTest2 : [a: 0, b: 1]

type SubTup2VariadicAndRest<T extends unknown[]> = T extends [
>SubTup2VariadicAndRest : SubTup2VariadicAndRest<T>

...infer B extends [any, any],
...(infer C)[]
]
? [...B, ...[C]]
: never;

type SubTup2VariadicAndRestTest = SubTup2VariadicAndRest<[a: 0, b: 1, ...c: 2[]]>;
>SubTup2VariadicAndRestTest : [0, 1, 2]

type SubTup2TrailingVariadic<T extends unknown[]> = T extends [
>SubTup2TrailingVariadic : SubTup2TrailingVariadic<T>

...any,
...infer B extends [any, any],
]
? B
: never;

type SubTup2TrailingVariadicTest = SubTup2TrailingVariadic<[...a: 0[], b: 1, c: 2]>;
>SubTup2TrailingVariadicTest : [b: 1, c: 2]

type SubTup2TrailingVariadicTest2 = SubTup2TrailingVariadic<[...a: 0[], b: 1, c: 2, d: 3]>;
>SubTup2TrailingVariadicTest2 : [c: 2, d: 3]

type SubTup2RestAndTrailingVariadic2<T extends unknown[]> = T extends [
>SubTup2RestAndTrailingVariadic2 : SubTup2RestAndTrailingVariadic2<T>

...(infer C)[],
...infer B extends [any, any],
]
? [C, ...B]
: never;

type SubTup2RestAndTrailingVariadic2Test = SubTup2RestAndTrailingVariadic2<[...a: 0[], b: 1, c: 2]>;
>SubTup2RestAndTrailingVariadic2Test : [0, 1, 2]

type SubTup2VariadicWithLeadingFixedElements<T extends unknown[]> = T extends [
>SubTup2VariadicWithLeadingFixedElements : SubTup2VariadicWithLeadingFixedElements<T>

any,
...infer B extends [any, any],
...any
]
? B
: never;

type SubTup2VariadicWithLeadingFixedElementsTest = SubTup2VariadicWithLeadingFixedElements<[a: 0, b: 1, c: 2, ...d: 3[]]>;
>SubTup2VariadicWithLeadingFixedElementsTest : [b: 1, c: 2]

type SubTup2VariadicWithLeadingFixedElementsTest2 = SubTup2VariadicWithLeadingFixedElements<[a: 0, b: 1, c: 2, d: 3, ...e: 4[]]>;
>SubTup2VariadicWithLeadingFixedElementsTest2 : [b: 1, c: 2]

type SubTup2TrailingVariadicWithTrailingFixedElements<T extends unknown[]> = T extends [
>SubTup2TrailingVariadicWithTrailingFixedElements : SubTup2TrailingVariadicWithTrailingFixedElements<T>

...any,
...infer B extends [any, any],
any,
]
? B
: never;

type SubTup2TrailingVariadicWithTrailingFixedElementsTest = SubTup2TrailingVariadicWithTrailingFixedElements<[...a: 0[], b: 1, c: 2, d: 3]>;
>SubTup2TrailingVariadicWithTrailingFixedElementsTest : [b: 1, c: 2]

type SubTup2TrailingVariadicWithTrailingFixedElementsTest2 = SubTup2TrailingVariadicWithTrailingFixedElements<[...a: 0[], b: 1, c: 2, d: 3, e: 4]>;
>SubTup2TrailingVariadicWithTrailingFixedElementsTest2 : [c: 2, d: 3]

73 changes: 73 additions & 0 deletions tests/cases/compiler/inferTypesWithFixedTupleExtendsAtVariadicPosition.ts
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// @strict: true
// @noEmit: true

// repro #51138

type SubTup2FixedLength<T extends unknown[]> = T extends [
...infer B extends [any, any],
any
]
? B
: never;

type SubTup2FixedLengthTest = SubTup2FixedLength<[a: 0, b: 1, c: 2]>;

type SubTup2Variadic<T extends unknown[]> = T extends [
...infer B extends [any, any],
...any
]
? B
: never;

type SubTup2VariadicTest = SubTup2Variadic<[a: 0, b: 1, ...c: 2[]]>;
type SubTup2VariadicTest2 = SubTup2Variadic<[a: 0, b: 1, c: 2, ...d: 3[]]>;

type SubTup2VariadicAndRest<T extends unknown[]> = T extends [
...infer B extends [any, any],
...(infer C)[]
]
? [...B, ...[C]]
: never;

type SubTup2VariadicAndRestTest = SubTup2VariadicAndRest<[a: 0, b: 1, ...c: 2[]]>;

type SubTup2TrailingVariadic<T extends unknown[]> = T extends [
...any,
...infer B extends [any, any],
]
? B
: never;

type SubTup2TrailingVariadicTest = SubTup2TrailingVariadic<[...a: 0[], b: 1, c: 2]>;
type SubTup2TrailingVariadicTest2 = SubTup2TrailingVariadic<[...a: 0[], b: 1, c: 2, d: 3]>;

type SubTup2RestAndTrailingVariadic2<T extends unknown[]> = T extends [
...(infer C)[],
...infer B extends [any, any],
]
? [C, ...B]
: never;

type SubTup2RestAndTrailingVariadic2Test = SubTup2RestAndTrailingVariadic2<[...a: 0[], b: 1, c: 2]>;

type SubTup2VariadicWithLeadingFixedElements<T extends unknown[]> = T extends [
any,
...infer B extends [any, any],
...any
]
? B
: never;

type SubTup2VariadicWithLeadingFixedElementsTest = SubTup2VariadicWithLeadingFixedElements<[a: 0, b: 1, c: 2, ...d: 3[]]>;
type SubTup2VariadicWithLeadingFixedElementsTest2 = SubTup2VariadicWithLeadingFixedElements<[a: 0, b: 1, c: 2, d: 3, ...e: 4[]]>;

type SubTup2TrailingVariadicWithTrailingFixedElements<T extends unknown[]> = T extends [
...any,
...infer B extends [any, any],
any,
]
? B
: never;

type SubTup2TrailingVariadicWithTrailingFixedElementsTest = SubTup2TrailingVariadicWithTrailingFixedElements<[...a: 0[], b: 1, c: 2, d: 3]>;
type SubTup2TrailingVariadicWithTrailingFixedElementsTest2 = SubTup2TrailingVariadicWithTrailingFixedElements<[...a: 0[], b: 1, c: 2, d: 3, e: 4]>;