Remove carve-out in conditional type instantiation that hopefully has been rendered unneeded

src/compiler/checker.ts

@@ -16374,11 +16374,7 @@ namespace ts {
                             }
                         }
                     }
-                    // We skip inference of the possible `infer` types unles the `extendsType` _is_ an infer type
-                    // if it was, it's trivial to say that extendsType = checkType, however such a pattern is used to
-                    // "reset" the type being build up during constraint calculation and avoid making an apparently "infinite" constraint
-                    // so in those cases we refain from performing inference and retain the uninfered type parameter
-                    if (!checkTypeInstantiable || !some(root.inferTypeParameters, t => t === extendsType)) {
+                    if (!checkTypeInstantiable) {
                         // We don't want inferences from constraints as they may cause us to eagerly resolve the
                         // conditional type instead of deferring resolution. Also, we always want strict function
                         // types rules (i.e. proper contravariance) for inferences.

tests/baselines/reference/recursiveTypeAliasWithSpreadConditionalReturnNotCircular.js

@@ -0,0 +1,33 @@
+//// [recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts]
+export {}
+export interface Option<T> {
+	zip1<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray1<O>]>;
+
+	zip2<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray2<O>]>;
+
+	zip3<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray3<O>]>;
+}
+
+type UnzipOption<T> = T extends Option<infer V> ? V : never;
+
+/// This doesn't work
+type UnzipOptionArray1<T> = { [k in keyof T]: T[k] extends Option<any> ? UnzipOption<T[k]> : never };
+
+/// But these work
+type UnzipOptionArray2<T> = { [k in keyof T]: UnzipOption<T[k]> };
+type UnzipOptionArray3<T> = { [k in keyof T]: T[k] extends Option<infer V> ? V : never };
+
+declare const opt1: Option<number>;
+declare const opt2: Option<string>;
+declare const opt3: Option<boolean>;
+
+const zipped1 = opt1.zip1(opt2, opt3);
+const zipped2 = opt1.zip2(opt2, opt3);
+const zipped3 = opt1.zip3(opt2, opt3);
+
+//// [recursiveTypeAliasWithSpreadConditionalReturnNotCircular.js]
+"use strict";
+exports.__esModule = true;
+var zipped1 = opt1.zip1(opt2, opt3);
+var zipped2 = opt1.zip2(opt2, opt3);
+var zipped3 = opt1.zip3(opt2, opt3);

tests/baselines/reference/recursiveTypeAliasWithSpreadConditionalReturnNotCircular.symbols

@@ -0,0 +1,121 @@
+=== tests/cases/compiler/recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts ===
+export {}
+export interface Option<T> {
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 1, 24))
+
+	zip1<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray1<O>]>;
+>zip1 : Symbol(Option.zip1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 1, 28))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 2, 6))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>others : Symbol(others, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 2, 36))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 2, 6))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 1, 24))
+>UnzipOptionArray1 : Symbol(UnzipOptionArray1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 9, 60))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 2, 6))
+
+	zip2<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray2<O>]>;
+>zip2 : Symbol(Option.zip2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 2, 88))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 4, 6))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>others : Symbol(others, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 4, 36))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 4, 6))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 1, 24))
+>UnzipOptionArray2 : Symbol(UnzipOptionArray2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 101))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 4, 6))
+
+	zip3<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray3<O>]>;
+>zip3 : Symbol(Option.zip3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 4, 88))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 6, 6))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>others : Symbol(others, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 6, 36))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 6, 6))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 1, 24))
+>UnzipOptionArray3 : Symbol(UnzipOptionArray3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 15, 66))
+>O : Symbol(O, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 6, 6))
+}
+
+type UnzipOption<T> = T extends Option<infer V> ? V : never;
+>UnzipOption : Symbol(UnzipOption, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 7, 1))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 9, 17))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 9, 17))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>V : Symbol(V, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 9, 44))
+>V : Symbol(V, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 9, 44))
+
+/// This doesn't work
+type UnzipOptionArray1<T> = { [k in keyof T]: T[k] extends Option<any> ? UnzipOption<T[k]> : never };
+>UnzipOptionArray1 : Symbol(UnzipOptionArray1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 9, 60))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 23))
+>k : Symbol(k, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 31))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 23))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 23))
+>k : Symbol(k, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 31))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>UnzipOption : Symbol(UnzipOption, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 7, 1))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 23))
+>k : Symbol(k, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 31))
+
+/// But these work
+type UnzipOptionArray2<T> = { [k in keyof T]: UnzipOption<T[k]> };
+>UnzipOptionArray2 : Symbol(UnzipOptionArray2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 12, 101))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 15, 23))
+>k : Symbol(k, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 15, 31))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 15, 23))
+>UnzipOption : Symbol(UnzipOption, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 7, 1))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 15, 23))
+>k : Symbol(k, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 15, 31))
+
+type UnzipOptionArray3<T> = { [k in keyof T]: T[k] extends Option<infer V> ? V : never };
+>UnzipOptionArray3 : Symbol(UnzipOptionArray3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 15, 66))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 16, 23))
+>k : Symbol(k, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 16, 31))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 16, 23))
+>T : Symbol(T, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 16, 23))
+>k : Symbol(k, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 16, 31))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+>V : Symbol(V, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 16, 71))
+>V : Symbol(V, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 16, 71))
+
+declare const opt1: Option<number>;
+>opt1 : Symbol(opt1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 18, 13))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+
+declare const opt2: Option<string>;
+>opt2 : Symbol(opt2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 19, 13))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+
+declare const opt3: Option<boolean>;
+>opt3 : Symbol(opt3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 20, 13))
+>Option : Symbol(Option, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 0, 9))
+
+const zipped1 = opt1.zip1(opt2, opt3);
+>zipped1 : Symbol(zipped1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 22, 5))
+>opt1.zip1 : Symbol(Option.zip1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 1, 28))
+>opt1 : Symbol(opt1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 18, 13))
+>zip1 : Symbol(Option.zip1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 1, 28))
+>opt2 : Symbol(opt2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 19, 13))
+>opt3 : Symbol(opt3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 20, 13))
+
+const zipped2 = opt1.zip2(opt2, opt3);
+>zipped2 : Symbol(zipped2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 23, 5))
+>opt1.zip2 : Symbol(Option.zip2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 2, 88))
+>opt1 : Symbol(opt1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 18, 13))
+>zip2 : Symbol(Option.zip2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 2, 88))
+>opt2 : Symbol(opt2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 19, 13))
+>opt3 : Symbol(opt3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 20, 13))
+
+const zipped3 = opt1.zip3(opt2, opt3);
+>zipped3 : Symbol(zipped3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 24, 5))
+>opt1.zip3 : Symbol(Option.zip3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 4, 88))
+>opt1 : Symbol(opt1, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 18, 13))
+>zip3 : Symbol(Option.zip3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 4, 88))
+>opt2 : Symbol(opt2, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 19, 13))
+>opt3 : Symbol(opt3, Decl(recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts, 20, 13))
+

tests/baselines/reference/recursiveTypeAliasWithSpreadConditionalReturnNotCircular.types

@@ -0,0 +1,66 @@
+=== tests/cases/compiler/recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts ===
+export {}
+export interface Option<T> {
+	zip1<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray1<O>]>;
+>zip1 : <O extends Option<any>[]>(...others: O) => Option<[T, ...UnzipOptionArray1<O>]>
+>others : O
+
+	zip2<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray2<O>]>;
+>zip2 : <O extends Option<any>[]>(...others: O) => Option<[T, ...UnzipOptionArray2<O>]>
+>others : O
+
+	zip3<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray3<O>]>;
+>zip3 : <O extends Option<any>[]>(...others: O) => Option<[T, ...UnzipOptionArray3<O>]>
+>others : O
+}
+
+type UnzipOption<T> = T extends Option<infer V> ? V : never;
+>UnzipOption : UnzipOption<T>
+
+/// This doesn't work
+type UnzipOptionArray1<T> = { [k in keyof T]: T[k] extends Option<any> ? UnzipOption<T[k]> : never };
+>UnzipOptionArray1 : UnzipOptionArray1<T>
+
+/// But these work
+type UnzipOptionArray2<T> = { [k in keyof T]: UnzipOption<T[k]> };
+>UnzipOptionArray2 : UnzipOptionArray2<T>
+
+type UnzipOptionArray3<T> = { [k in keyof T]: T[k] extends Option<infer V> ? V : never };
+>UnzipOptionArray3 : UnzipOptionArray3<T>
+
+declare const opt1: Option<number>;
+>opt1 : Option<number>
+
+declare const opt2: Option<string>;
+>opt2 : Option<string>
+
+declare const opt3: Option<boolean>;
+>opt3 : Option<boolean>
+
+const zipped1 = opt1.zip1(opt2, opt3);
+>zipped1 : Option<[number, string, boolean]>
+>opt1.zip1(opt2, opt3) : Option<[number, string, boolean]>
+>opt1.zip1 : <O extends Option<any>[]>(...others: O) => Option<[number, ...UnzipOptionArray1<O>]>
+>opt1 : Option<number>
+>zip1 : <O extends Option<any>[]>(...others: O) => Option<[number, ...UnzipOptionArray1<O>]>
+>opt2 : Option<string>
+>opt3 : Option<boolean>
+
+const zipped2 = opt1.zip2(opt2, opt3);
+>zipped2 : Option<[number, string, boolean]>
+>opt1.zip2(opt2, opt3) : Option<[number, string, boolean]>
+>opt1.zip2 : <O extends Option<any>[]>(...others: O) => Option<[number, ...UnzipOptionArray2<O>]>
+>opt1 : Option<number>
+>zip2 : <O extends Option<any>[]>(...others: O) => Option<[number, ...UnzipOptionArray2<O>]>
+>opt2 : Option<string>
+>opt3 : Option<boolean>
+
+const zipped3 = opt1.zip3(opt2, opt3);
+>zipped3 : Option<[number, string, boolean]>
+>opt1.zip3(opt2, opt3) : Option<[number, string, boolean]>
+>opt1.zip3 : <O extends Option<any>[]>(...others: O) => Option<[number, ...UnzipOptionArray3<O>]>
+>opt1 : Option<number>
+>zip3 : <O extends Option<any>[]>(...others: O) => Option<[number, ...UnzipOptionArray3<O>]>
+>opt2 : Option<string>
+>opt3 : Option<boolean>
+

tests/cases/compiler/recursiveTypeAliasWithSpreadConditionalReturnNotCircular.ts

@@ -0,0 +1,25 @@
+export {}
+export interface Option<T> {
+	zip1<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray1<O>]>;
+
+	zip2<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray2<O>]>;
+
+	zip3<O extends Array<Option<any>>>(...others: O): Option<[T, ...UnzipOptionArray3<O>]>;
+}
+
+type UnzipOption<T> = T extends Option<infer V> ? V : never;
+
+/// This doesn't work
+type UnzipOptionArray1<T> = { [k in keyof T]: T[k] extends Option<any> ? UnzipOption<T[k]> : never };
+
+/// But these work
+type UnzipOptionArray2<T> = { [k in keyof T]: UnzipOption<T[k]> };
+type UnzipOptionArray3<T> = { [k in keyof T]: T[k] extends Option<infer V> ? V : never };
+
+declare const opt1: Option<number>;
+declare const opt2: Option<string>;
+declare const opt3: Option<boolean>;
+
+const zipped1 = opt1.zip1(opt2, opt3);
+const zipped2 = opt1.zip2(opt2, opt3);
+const zipped3 = opt1.zip3(opt2, opt3);