Tweak co/contra inference logic from #52123

src/compiler/checker.ts

@@ -24579,8 +24579,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     // parameter and has inferences that would conflict. Otherwise, we use the contra-variant inference.
                     const useCovariantType = inferredCovariantType && !(inferredCovariantType.flags & TypeFlags.Never) &&
                         some(inference.contraCandidates, t => isTypeSubtypeOf(inferredCovariantType, t)) &&
-                        every(context.inferences, other => other === inference ||
-                            getConstraintOfTypeParameter(other.typeParameter) !== inference.typeParameter ||
+                        every(context.inferences, other =>
+                            other !== inference && getConstraintOfTypeParameter(other.typeParameter) !== inference.typeParameter ||
                             every(other.candidates, t => isTypeSubtypeOf(t, inferredCovariantType)));
                     inferredType = useCovariantType ? inferredCovariantType : getContravariantInference(inference);
                 }

tests/baselines/reference/coAndContraVariantInferences3.js

@@ -0,0 +1,163 @@
+//// [coAndContraVariantInferences3.ts]
+interface DeprecationOptions {
+    message?: string;
+    error?: boolean;
+    name?: string;
+}
+
+type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends ((k: infer I) => void) ? I : never;
+
+type OverloadDefinitions = { readonly [P in number]: (...args: any[]) => any; };
+
+type OverloadBinder<T extends OverloadDefinitions> = (args: OverloadParameters<T>) => OverloadKeys<T> | undefined;
+
+type OverloadKeys<T extends OverloadDefinitions> = Extract<keyof T, number>;
+
+type OverloadParameters<T extends OverloadDefinitions> = Parameters<{ [P in OverloadKeys<T>]: T[P]; }[OverloadKeys<T>]>;
+
+type OverloadFunction<T extends OverloadDefinitions> = UnionToIntersection<T[keyof T]>;
+
+type OverloadBinders<T extends OverloadDefinitions> = { [P in OverloadKeys<T>]: (args: OverloadParameters<T>) => boolean | undefined; };
+
+type OverloadDeprecations<T extends OverloadDefinitions> = { [P in OverloadKeys<T>]?: DeprecationOptions; };
+
+declare function createOverload<T extends OverloadDefinitions>(name: string, overloads: T, binder: OverloadBinders<T>, deprecations?: OverloadDeprecations<T>): UnionToIntersection<T[keyof T]>;
+
+declare function createBinder<T extends OverloadDefinitions>(overloads: T, binder: OverloadBinders<T>): OverloadBinder<T>;
+
+interface OverloadBuilder {
+    overload<T extends OverloadDefinitions>(overloads: T): BindableOverloadBuilder<T>;
+}
+
+interface BindableOverloadBuilder<T extends OverloadDefinitions> {
+    bind(binder: OverloadBinders<T>): BoundOverloadBuilder<T>;
+}
+
+interface FinishableOverloadBuilder<T extends OverloadDefinitions> {
+    finish(): OverloadFunction<T>;
+}
+
+interface BoundOverloadBuilder<T extends OverloadDefinitions> extends FinishableOverloadBuilder<T> {
+    deprecate(deprecations: OverloadDeprecations<T>): FinishableOverloadBuilder<T>;
+}
+
+declare function buildOverload(name: string): OverloadBuilder;
+
+const enum SyntaxKind {
+    ImportDeclaration,
+    Modifier,
+    ImportClause,
+    AssertClause,
+    Decorator
+}
+
+interface Node {
+    kind: SyntaxKind;
+}
+
+interface Declaration extends Node { _declarationBrand: any }
+interface Statement extends Node { _statementBrand: any };
+interface Expression extends Node { _expressionBrand: any; }
+
+interface ImportDeclaration extends Statement { kind: SyntaxKind.ImportDeclaration; }
+interface Modifier extends Node { kind: SyntaxKind.Modifier; }
+interface Decorator extends Node { kind: SyntaxKind.Decorator; }
+interface ImportClause extends Declaration { kind: SyntaxKind.ImportClause; }
+interface AssertClause extends Node { kind: SyntaxKind.AssertClause; }
+
+declare function isExpression(node: Node): node is Expression;
+declare function isAssertClause(node: Node): node is AssertClause;
+declare function isImportClause(node: Node): node is ImportClause;
+declare function isModifier(node: Node): node is Modifier;
+declare function isDecorator(node: Node): node is Decorator;
+
+declare const updateImportDeclaration: {
+    (node: ImportDeclaration, modifiers: readonly Modifier[] | undefined, importClause: ImportClause | undefined, moduleSpecifier: Expression, assertClause: AssertClause | undefined): ImportDeclaration;
+    (node: ImportDeclaration, decorators: readonly Decorator[] | undefined, modifiers: readonly Modifier[] | undefined, importClause: ImportClause | undefined, moduleSpecifier: Expression, assertClause: AssertClause | undefined): ImportDeclaration;
+}
+
+declare function every<T, U extends T>(array: readonly T[], callback: (element: T, index: number) => element is U): array is readonly U[];
+declare function every<T, U extends T>(array: readonly T[] | undefined, callback: (element: T, index: number) => element is U): array is readonly U[] | undefined;
+declare function every<T>(array: readonly T[] | undefined, callback: (element: T, index: number) => boolean): boolean;
+
+declare function isArray(value: any): value is readonly unknown[];
+
+declare const DISALLOW_DECORATORS: DeprecationOptions;
+
+buildOverload("updateImportDeclaration")
+    .overload({
+        0(node: ImportDeclaration, modifiers: readonly Modifier[] | undefined, importClause: ImportClause | undefined, moduleSpecifier: Expression, assertClause: AssertClause | undefined): ImportDeclaration {
+            return updateImportDeclaration(node, modifiers, importClause, moduleSpecifier, assertClause);
+        },
+
+        1(node: ImportDeclaration, _decorators: readonly Decorator[] | undefined, modifiers: readonly Modifier[] | undefined, importClause: ImportClause | undefined, moduleSpecifier: Expression, assertClause: AssertClause | undefined): ImportDeclaration {
+            return updateImportDeclaration(node, modifiers, importClause, moduleSpecifier, assertClause);
+        },
+    })
+    .bind({
+        0: ([, modifiers, importClause, moduleSpecifier, assertClause, other]) =>
+            (other === undefined) &&
+            (modifiers === undefined || every(modifiers, isModifier)) &&
+            (importClause === undefined || !isArray(importClause)) &&
+            (moduleSpecifier === undefined || isExpression(moduleSpecifier)) &&
+            (assertClause === undefined || isAssertClause(assertClause)),
+
+        1: ([, decorators, modifiers, importClause, moduleSpecifier, assertClause]) =>
+            (decorators === undefined || every(decorators, isDecorator)) &&
+            (modifiers === undefined || isArray(modifiers)) &&
+            (importClause === undefined || isImportClause(importClause)) &&
+            (moduleSpecifier !== undefined && isExpression(moduleSpecifier)) &&
+            (assertClause === undefined || isAssertClause(assertClause)),
+    })
+    .deprecate({
+        1: DISALLOW_DECORATORS
+    })
+    .finish();
+
+
+declare const modifiers: readonly Modifier[] | readonly Decorator[];
+
+function foo() {
+    every(modifiers, isModifier);
+    every(modifiers, isDecorator);
+}
+
+
+//// [coAndContraVariantInferences3.js]
+"use strict";
+;
+buildOverload("updateImportDeclaration")
+    .overload({
+    0: function (node, modifiers, importClause, moduleSpecifier, assertClause) {
+        return updateImportDeclaration(node, modifiers, importClause, moduleSpecifier, assertClause);
+    },
+    1: function (node, _decorators, modifiers, importClause, moduleSpecifier, assertClause) {
+        return updateImportDeclaration(node, modifiers, importClause, moduleSpecifier, assertClause);
+    },
+})
+    .bind({
+    0: function (_a) {
+        var modifiers = _a[1], importClause = _a[2], moduleSpecifier = _a[3], assertClause = _a[4], other = _a[5];
+        return (other === undefined) &&
+            (modifiers === undefined || every(modifiers, isModifier)) &&
+            (importClause === undefined || !isArray(importClause)) &&
+            (moduleSpecifier === undefined || isExpression(moduleSpecifier)) &&
+            (assertClause === undefined || isAssertClause(assertClause));
+    },
+    1: function (_a) {
+        var decorators = _a[1], modifiers = _a[2], importClause = _a[3], moduleSpecifier = _a[4], assertClause = _a[5];
+        return (decorators === undefined || every(decorators, isDecorator)) &&
+            (modifiers === undefined || isArray(modifiers)) &&
+            (importClause === undefined || isImportClause(importClause)) &&
+            (moduleSpecifier !== undefined && isExpression(moduleSpecifier)) &&
+            (assertClause === undefined || isAssertClause(assertClause));
+    },
+})
+    .deprecate({
+    1: DISALLOW_DECORATORS
+})
+    .finish();
+function foo() {
+    every(modifiers, isModifier);
+    every(modifiers, isDecorator);
+}