no-duplicate-spread-property: handle intersection types (#449)

Author: ajafff

baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint

@@ -260,3 +260,38 @@ var v: any;
     get foo() { return 2; },
     set foo(v: number) {},
 });
+
+({
+    foo: 1,
+    ~~~     [error no-duplicate-spread-property: Property 'foo' is overridden later.]
+    bar: 1,
+    ~~~     [error no-duplicate-spread-property: Property 'bar' is overridden later.]
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    bas: 1,
+});
+
+({
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    foo: 1,
+    bar: 1,
+    bas: 1,
+});
+
+({
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: All properties of this object are overridden later.]
+    foo: 1,
+    bar: 1,
+    baz: 1,
+});
+
+({
+    bar: 1,
+    ~~~     [error no-duplicate-spread-property: Property 'bar' is overridden later.]
+    ...get<{bar: number} & Record<string, number>>(),
+});
+
+({
+    ...get<{bar: number} & Record<string, number>>(),
+    bar: 1,
+});

baselines/packages/mimir/test/no-duplicate-spread-property/loose/test.ts.lint

@@ -232,3 +232,34 @@ var v: any;
     get foo() { return 2; },
     set foo(v: number) {},
 });
+
+({
+    foo: 1,
+    bar: 1,
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    bas: 1,
+});
+
+({
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    foo: 1,
+    bar: 1,
+    bas: 1,
+});
+
+({
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    foo: 1,
+    bar: 1,
+    baz: 1,
+});
+
+({
+    bar: 1,
+    ...get<{bar: number} & Record<string, number>>(),
+});
+
+({
+    ...get<{bar: number} & Record<string, number>>(),
+    bar: 1,
+});

packages/mimir/src/rules/no-duplicate-spread-property.ts

@@ -1,6 +1,6 @@
 import { TypedRule, excludeDeclarationFiles, requiresCompilerOption } from '@fimbul/ymir';
 import * as ts from 'typescript';
-import { isReassignmentTarget, isObjectType, unionTypeParts, isClassLikeDeclaration, getPropertyName } from 'tsutils';
+import { isReassignmentTarget, isObjectType, unionTypeParts, isClassLikeDeclaration, getPropertyName, isIntersectionType } from 'tsutils';
 import { lateBoundPropertyNames } from '../utils';
 
 interface PropertyInfo {
@@ -88,11 +88,13 @@ export class Rule extends TypedRule {
 
     private getPropertyInfoFromSpread(node: ts.Expression): PropertyInfo {
         const type = this.checker.getTypeAtLocation(node)!;
-        return unionTypeParts(type).map(getPropertyInfoFromType).reduce(combinePropertyInfo);
+        return unionTypeParts(type).map(getPropertyInfoFromType).reduce(unionPropertyInfo);
     }
 }
 
 function getPropertyInfoFromType(type: ts.Type): PropertyInfo {
+    if (isIntersectionType(type))
+        return type.types.map(getPropertyInfoFromType).reduce(intersectPropertyInfo);
     if (!isObjectType(type))
         return emptyPropertyInfo;
     const result: PropertyInfo = {
@@ -118,10 +120,18 @@ function isSpreadableProperty(prop: ts.Symbol): boolean | undefined {
     return true;
 }
 
-function combinePropertyInfo(a: PropertyInfo, b: PropertyInfo): PropertyInfo {
+function unionPropertyInfo(a: PropertyInfo, b: PropertyInfo): PropertyInfo {
     return {
         known: a.known && b.known,
         names: [...a.names, ...b.names],
         assignedNames: a.assignedNames.filter((name) => b.assignedNames.includes(name)),
     };
 }
+
+function intersectPropertyInfo(a: PropertyInfo, b: PropertyInfo): PropertyInfo {
+    return {
+        known: a.known && b.known,
+        names: [...a.names, ...b.names],
+        assignedNames: [...a.assignedNames, ...b.assignedNames],
+    };
+}

packages/mimir/test/no-duplicate-spread-property/test.ts

@@ -232,3 +232,34 @@ var v: any;
     get foo() { return 2; },
     set foo(v: number) {},
 });
+
+({
+    foo: 1,
+    bar: 1,
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    bas: 1,
+});
+
+({
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    foo: 1,
+    bar: 1,
+    bas: 1,
+});
+
+({
+    ...get<{bar: number} & Record<'foo' | 'baz', number>>(),
+    foo: 1,
+    bar: 1,
+    baz: 1,
+});
+
+({
+    bar: 1,
+    ...get<{bar: number} & Record<string, number>>(),
+});
+
+({
+    ...get<{bar: number} & Record<string, number>>(),
+    bar: 1,
+});