Skip to content

Properly account for start length when inferring into two variadic tuple elements when implied arity is available #62563

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 5 commits into
base: main
Choose a base branch
from
+394 −1
Open

Properly account for start length when inferring into two variadic tuple elements when implied arity is available #62563

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
6d4d06b
Properly account for start length when inferring into two variadic tu…
Andarist Oct 8, 2025
e7ad723
fix computation
Andarist Oct 8, 2025
a340459
simplify
Andarist Oct 8, 2025
8bd5c85
more tests
Andarist Oct 8, 2025
5942d7b
make computation clearer
Andarist Oct 8, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 2 additions & 1 deletion src/compiler/checker.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -27319,7 +27319,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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]);
const otherImpliedArity = sourceArity - targetInfo.impliedArity - startLength - endLength; // implied arity of U
inferFromTypes(sliceTupleType(source, startLength, endLength + otherImpliedArity), elementTypes[startLength]);
inferFromTypes(sliceTupleType(source, startLength + targetInfo.impliedArity, endLength), elementTypes[startLength + 1]);
}
}
Expand Down
120 changes: 120 additions & 0 deletions tests/baselines/reference/variadicTuples4.symbols
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,120 @@
//// [tests/cases/conformance/types/tuple/variadicTuples4.ts] ////

=== variadicTuples4.ts ===
// https://github.com/microsoft/TypeScript/issues/62561

function f<T extends unknown[], V extends unknown[]>(
>f : Symbol(f, Decl(variadicTuples4.ts, 0, 0))
>T : Symbol(T, Decl(variadicTuples4.ts, 2, 11))
>V : Symbol(V, Decl(variadicTuples4.ts, 2, 31))

x: [boolean, ...V, ...T],
>x : Symbol(x, Decl(variadicTuples4.ts, 2, 53))
>V : Symbol(V, Decl(variadicTuples4.ts, 2, 31))
>T : Symbol(T, Decl(variadicTuples4.ts, 2, 11))

...args: V
>args : Symbol(args, Decl(variadicTuples4.ts, 3, 27))
>V : Symbol(V, Decl(variadicTuples4.ts, 2, 31))

) {
return x;
>x : Symbol(x, Decl(variadicTuples4.ts, 2, 53))
}

const a = f([true, 2, "b", true], 1, "a"); // ok
>a : Symbol(a, Decl(variadicTuples4.ts, 9, 5))
>f : Symbol(f, Decl(variadicTuples4.ts, 0, 0))

function f2<T extends unknown[], V extends unknown[]>(
>f2 : Symbol(f2, Decl(variadicTuples4.ts, 9, 42))
>T : Symbol(T, Decl(variadicTuples4.ts, 11, 12))
>V : Symbol(V, Decl(variadicTuples4.ts, 11, 32))

x: [boolean, ...V, ...T, string],
>x : Symbol(x, Decl(variadicTuples4.ts, 11, 54))
>V : Symbol(V, Decl(variadicTuples4.ts, 11, 32))
>T : Symbol(T, Decl(variadicTuples4.ts, 11, 12))

...args: V
>args : Symbol(args, Decl(variadicTuples4.ts, 12, 35))
>V : Symbol(V, Decl(variadicTuples4.ts, 11, 32))

) {
return x;
>x : Symbol(x, Decl(variadicTuples4.ts, 11, 54))
}

const a2 = f2([true, 2, "b", true, "c"], 1, "a"); // ok
>a2 : Symbol(a2, Decl(variadicTuples4.ts, 18, 5))
>f2 : Symbol(f2, Decl(variadicTuples4.ts, 9, 42))

function f3<T extends unknown[], V extends unknown[]>(
>f3 : Symbol(f3, Decl(variadicTuples4.ts, 18, 49))
>T : Symbol(T, Decl(variadicTuples4.ts, 20, 12))
>V : Symbol(V, Decl(variadicTuples4.ts, 20, 32))

x: [boolean, ...V, ...T, string, number],
>x : Symbol(x, Decl(variadicTuples4.ts, 20, 54))
>V : Symbol(V, Decl(variadicTuples4.ts, 20, 32))
>T : Symbol(T, Decl(variadicTuples4.ts, 20, 12))

...args: V
>args : Symbol(args, Decl(variadicTuples4.ts, 21, 43))
>V : Symbol(V, Decl(variadicTuples4.ts, 20, 32))

) {
return x;
>x : Symbol(x, Decl(variadicTuples4.ts, 20, 54))
}

const a3 = f3([true, 2, "b", true, "c", 3], 1, "a"); // ok
>a3 : Symbol(a3, Decl(variadicTuples4.ts, 27, 5))
>f3 : Symbol(f3, Decl(variadicTuples4.ts, 18, 49))

function f4<T extends unknown[], V extends unknown[]>(
>f4 : Symbol(f4, Decl(variadicTuples4.ts, 27, 52))
>T : Symbol(T, Decl(variadicTuples4.ts, 29, 12))
>V : Symbol(V, Decl(variadicTuples4.ts, 29, 32))

x: [boolean, boolean, boolean, ...V, ...T, string, number],
>x : Symbol(x, Decl(variadicTuples4.ts, 29, 54))
>V : Symbol(V, Decl(variadicTuples4.ts, 29, 32))
>T : Symbol(T, Decl(variadicTuples4.ts, 29, 12))

...args: V
>args : Symbol(args, Decl(variadicTuples4.ts, 30, 61))
>V : Symbol(V, Decl(variadicTuples4.ts, 29, 32))

) {
return x;
>x : Symbol(x, Decl(variadicTuples4.ts, 29, 54))
}

const a4 = f4([true, true, true, 2, "b", true, "c", 3], 1, "a"); // ok
>a4 : Symbol(a4, Decl(variadicTuples4.ts, 36, 5))
>f4 : Symbol(f4, Decl(variadicTuples4.ts, 27, 52))

function f5<T extends unknown[], V extends unknown[]>(
>f5 : Symbol(f5, Decl(variadicTuples4.ts, 36, 64))
>T : Symbol(T, Decl(variadicTuples4.ts, 38, 12))
>V : Symbol(V, Decl(variadicTuples4.ts, 38, 32))

x: [boolean, boolean, boolean, ...V, ...T],
>x : Symbol(x, Decl(variadicTuples4.ts, 38, 54))
>V : Symbol(V, Decl(variadicTuples4.ts, 38, 32))
>T : Symbol(T, Decl(variadicTuples4.ts, 38, 12))

...args: V
>args : Symbol(args, Decl(variadicTuples4.ts, 39, 45))
>V : Symbol(V, Decl(variadicTuples4.ts, 38, 32))

) {
return x;
>x : Symbol(x, Decl(variadicTuples4.ts, 38, 54))
}

const a5 = f5([true, true, true, 2, "b", true], 1, "a"); // ok
>a5 : Symbol(a5, Decl(variadicTuples4.ts, 45, 5))
>f5 : Symbol(f5, Decl(variadicTuples4.ts, 36, 64))

223 changes: 223 additions & 0 deletions tests/baselines/reference/variadicTuples4.types
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,223 @@
//// [tests/cases/conformance/types/tuple/variadicTuples4.ts] ////

=== variadicTuples4.ts ===
// https://github.com/microsoft/TypeScript/issues/62561

function f<T extends unknown[], V extends unknown[]>(
>f : <T extends unknown[], V extends unknown[]>(x: [boolean, ...V, ...T], ...args: V) => [boolean, ...V, ...T]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^

x: [boolean, ...V, ...T],
>x : [boolean, ...V, ...T]
> : ^^^^^^^^^^^^^^^^^^^^^

...args: V
>args : V
> : ^

) {
return x;
>x : [boolean, ...V, ...T]
> : ^^^^^^^^^^^^^^^^^^^^^
}

const a = f([true, 2, "b", true], 1, "a"); // ok
>a : [boolean, number, string, boolean]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f([true, 2, "b", true], 1, "a") : [boolean, number, string, boolean]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f : <T extends unknown[], V extends unknown[]>(x: [boolean, ...V, ...T], ...args: V) => [boolean, ...V, ...T]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^
>[true, 2, "b", true] : [true, number, string, true]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>true : true
> : ^^^^
>2 : 2
> : ^
>"b" : "b"
> : ^^^
>true : true
> : ^^^^
>1 : 1
> : ^
>"a" : "a"
> : ^^^

function f2<T extends unknown[], V extends unknown[]>(
>f2 : <T extends unknown[], V extends unknown[]>(x: [boolean, ...V, ...T, string], ...args: V) => [boolean, ...V, ...T, string]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

x: [boolean, ...V, ...T, string],
>x : [boolean, ...V, ...T, string]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

...args: V
>args : V
> : ^

) {
return x;
>x : [boolean, ...V, ...T, string]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
}

const a2 = f2([true, 2, "b", true, "c"], 1, "a"); // ok
>a2 : [boolean, number, string, boolean, string]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f2([true, 2, "b", true, "c"], 1, "a") : [boolean, number, string, boolean, string]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f2 : <T extends unknown[], V extends unknown[]>(x: [boolean, ...V, ...T, string], ...args: V) => [boolean, ...V, ...T, string]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>[true, 2, "b", true, "c"] : [true, number, string, true, string]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>true : true
> : ^^^^
>2 : 2
> : ^
>"b" : "b"
> : ^^^
>true : true
> : ^^^^
>"c" : "c"
> : ^^^
>1 : 1
> : ^
>"a" : "a"
> : ^^^

function f3<T extends unknown[], V extends unknown[]>(
>f3 : <T extends unknown[], V extends unknown[]>(x: [boolean, ...V, ...T, string, number], ...args: V) => [boolean, ...V, ...T, string, number]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

x: [boolean, ...V, ...T, string, number],
>x : [boolean, ...V, ...T, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

...args: V
>args : V
> : ^

) {
return x;
>x : [boolean, ...V, ...T, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
}

const a3 = f3([true, 2, "b", true, "c", 3], 1, "a"); // ok
>a3 : [boolean, number, string, boolean, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f3([true, 2, "b", true, "c", 3], 1, "a") : [boolean, number, string, boolean, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f3 : <T extends unknown[], V extends unknown[]>(x: [boolean, ...V, ...T, string, number], ...args: V) => [boolean, ...V, ...T, string, number]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>[true, 2, "b", true, "c", 3] : [true, number, string, true, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>true : true
> : ^^^^
>2 : 2
> : ^
>"b" : "b"
> : ^^^
>true : true
> : ^^^^
>"c" : "c"
> : ^^^
>3 : 3
> : ^
>1 : 1
> : ^
>"a" : "a"
> : ^^^

function f4<T extends unknown[], V extends unknown[]>(
>f4 : <T extends unknown[], V extends unknown[]>(x: [boolean, boolean, boolean, ...V, ...T, string, number], ...args: V) => [boolean, boolean, boolean, ...V, ...T, string, number]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

x: [boolean, boolean, boolean, ...V, ...T, string, number],
>x : [boolean, boolean, boolean, ...V, ...T, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

...args: V
>args : V
> : ^

) {
return x;
>x : [boolean, boolean, boolean, ...V, ...T, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
}

const a4 = f4([true, true, true, 2, "b", true, "c", 3], 1, "a"); // ok
>a4 : [boolean, boolean, boolean, number, string, boolean, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f4([true, true, true, 2, "b", true, "c", 3], 1, "a") : [boolean, boolean, boolean, number, string, boolean, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f4 : <T extends unknown[], V extends unknown[]>(x: [boolean, boolean, boolean, ...V, ...T, string, number], ...args: V) => [boolean, boolean, boolean, ...V, ...T, string, number]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>[true, true, true, 2, "b", true, "c", 3] : [true, true, true, number, string, true, string, number]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>true : true
> : ^^^^
>true : true
> : ^^^^
>true : true
> : ^^^^
>2 : 2
> : ^
>"b" : "b"
> : ^^^
>true : true
> : ^^^^
>"c" : "c"
> : ^^^
>3 : 3
> : ^
>1 : 1
> : ^
>"a" : "a"
> : ^^^

function f5<T extends unknown[], V extends unknown[]>(
>f5 : <T extends unknown[], V extends unknown[]>(x: [boolean, boolean, boolean, ...V, ...T], ...args: V) => [boolean, boolean, boolean, ...V, ...T]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

x: [boolean, boolean, boolean, ...V, ...T],
>x : [boolean, boolean, boolean, ...V, ...T]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

...args: V
>args : V
> : ^

) {
return x;
>x : [boolean, boolean, boolean, ...V, ...T]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
}

const a5 = f5([true, true, true, 2, "b", true], 1, "a"); // ok
>a5 : [boolean, boolean, boolean, number, string, boolean]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f5([true, true, true, 2, "b", true], 1, "a") : [boolean, boolean, boolean, number, string, boolean]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>f5 : <T extends unknown[], V extends unknown[]>(x: [boolean, boolean, boolean, ...V, ...T], ...args: V) => [boolean, boolean, boolean, ...V, ...T]
> : ^ ^^^^^^^^^ ^^ ^^^^^^^^^ ^^ ^^ ^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>[true, true, true, 2, "b", true] : [true, true, true, number, string, true]
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>true : true
> : ^^^^
>true : true
> : ^^^^
>true : true
> : ^^^^
>2 : 2
> : ^
>"b" : "b"
> : ^^^
>true : true
> : ^^^^
>1 : 1
> : ^
>"a" : "a"
> : ^^^

Loading