From c378684655dbce4788e965130a2625a91d1bd525 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 12 Apr 2018 16:30:25 +0200
Subject: [PATCH 1/9] add some test cases

---
 .../default/test.ts.lint                      | 59 ++++++++++++
 .../src/rules/no-useless-object-property.ts   | 95 +++++++++++++++++++
 .../no-useless-object-property/.wotanrc.yaml  |  2 +
 .../default.test.json                         |  1 +
 .../test/no-useless-object-property/test.ts   | 52 ++++++++++
 .../no-useless-object-property/tsconfig.json  |  6 ++
 6 files changed, 215 insertions(+)
 create mode 100644 baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
 create mode 100644 packages/mimir/src/rules/no-useless-object-property.ts
 create mode 100644 packages/mimir/test/no-useless-object-property/.wotanrc.yaml
 create mode 100644 packages/mimir/test/no-useless-object-property/default.test.json
 create mode 100644 packages/mimir/test/no-useless-object-property/test.ts
 create mode 100644 packages/mimir/test/no-useless-object-property/tsconfig.json

diff --git a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
new file mode 100644
index 000000000..653dc2f43
--- /dev/null
+++ b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
@@ -0,0 +1,59 @@
+export {};
+
+declare function get<T>(): T;
+
+const foo = 'foo';
+
+({
+    x: 1,
+    ~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{x: 2, y: 2},
+    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    y: 1,
+    ...{x: 3},
+});
+
+({
+    foo,
+    ~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{foo},
+});
+
+({
+    [foo]: 1,
+    ~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{[foo]: 2},
+});
+
+({
+    [Symbol.iterator]: 1,
+    ~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{[Symbol.iterator]: 2},
+});
+
+({
+    [get<string>()]: 1,
+    ...{[get<string>()]: 2},
+});
+
+({
+    [get<'foo'>()]: 1,
+    ...{[get<'foo'>()]: 2},
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{[foo]: 3},
+});
+
+({
+    foo: 1,
+    bar: 1,
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    baz: 1,
+    ...get<{foo?: string, bar: number, baz: any}>(),
+});
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    ...get<{foo: string, bar: number} | {bar: number, baz: boolean}>(),
+});
diff --git a/packages/mimir/src/rules/no-useless-object-property.ts b/packages/mimir/src/rules/no-useless-object-property.ts
new file mode 100644
index 000000000..950ecc731
--- /dev/null
+++ b/packages/mimir/src/rules/no-useless-object-property.ts
@@ -0,0 +1,95 @@
+import { TypedRule, excludeDeclarationFiles } from '@fimbul/ymir';
+import * as ts from 'typescript';
+import { isReassignmentTarget, getPropertyName, isObjectType, unionTypeParts } from 'tsutils';
+
+@excludeDeclarationFiles
+export class Rule extends TypedRule {
+    public apply() {
+        const checkedObjects = new Set<number>();
+        for (const node of this.context.getFlatAst()) {
+            if (
+                node.kind === ts.SyntaxKind.SpreadAssignment &&
+                !checkedObjects.has(node.parent!.pos) &&
+                !isReassignmentTarget(<ts.ObjectLiteralExpression>node.parent)
+            ) {
+                checkedObjects.add(node.parent!.pos);
+                this.checkObject(<ts.ObjectLiteralExpression>node.parent);
+            }
+        }
+    }
+
+    private checkObject({properties}: ts.ObjectLiteralExpression) {
+        const propertiesSeen = new Set<string>();
+        for (let i = properties.length - 1; i >= 0; --i) {
+            const info = this.getPropertyInfo(properties[i]);
+            if (info.known && info.names.every((name) => propertiesSeen.has(name)))
+                this.addFailureAtNode(properties[i], 'Property is overridden later.');
+            for (const name of info.assignedNames)
+                propertiesSeen.add(name);
+        }
+    }
+
+    private getPropertyInfo(property: ts.ObjectLiteralElementLike): PropertyInfo {
+        switch (property.kind) {
+            case ts.SyntaxKind.SpreadAssignment:
+                return this.getPropertyInfoFromSpread(property.expression);
+            case ts.SyntaxKind.ShorthandPropertyAssignment:
+                return {
+                    known: true,
+                    names: [property.name.text],
+                    assignedNames: [property.name.text],
+                };
+            default: {
+                const name = getPropertyName(property.name) ||
+                    getNameOfSymbol(this.checker.getSymbolAtLocation(property.name));
+                if (name === undefined)
+                    return {
+                        known: false,
+                        names: [],
+                        assignedNames: [],
+                    };
+                return {
+                    known: true,
+                    names: [name],
+                    assignedNames: [name],
+                };
+            }
+        }
+    }
+
+    private getPropertyInfoFromSpread(node: ts.Expression): PropertyInfo {
+        const type = this.checker.getTypeAtLocation(node);
+        if (!isObjectType(type))
+            return {
+                known: false,
+                names: [],
+                assignedNames: [],
+            };
+        const result: PropertyInfo = {
+            known: (type.flags & ts.TypeFlags.Any) !== 0 ||
+                type.getStringIndexType() === undefined && type.getNumberIndexType() === undefined,
+            names: [],
+            assignedNames: [],
+        };
+        for (const prop of type.getProperties()) {
+            if (!unionTypeParts(this.checker.getTypeOfSymbolAtLocation(prop, node)).some(isOptionalType))
+                result.assignedNames.push(prop.name);
+            result.names.push(prop.name);
+        }
+        return result;
+    }
+}
+
+function isOptionalType(type: ts.Type) {
+    return (type.flags & (ts.TypeFlags.Undefined | ts.TypeFlags.Any)) !== 0;
+}
+
+function getNameOfSymbol(symbol: ts.Symbol | undefined) {
+    return symbol && symbol.name;
+}
+
+interface PropertyInfo {
+    known: boolean;
+    names: string[];
+    assignedNames: string[];
+}
diff --git a/packages/mimir/test/no-useless-object-property/.wotanrc.yaml b/packages/mimir/test/no-useless-object-property/.wotanrc.yaml
new file mode 100644
index 000000000..4792501a3
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/.wotanrc.yaml
@@ -0,0 +1,2 @@
+rules:
+  no-useless-object-property: error
diff --git a/packages/mimir/test/no-useless-object-property/default.test.json b/packages/mimir/test/no-useless-object-property/default.test.json
new file mode 100644
index 000000000..0967ef424
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/default.test.json
@@ -0,0 +1 @@
+{}
diff --git a/packages/mimir/test/no-useless-object-property/test.ts b/packages/mimir/test/no-useless-object-property/test.ts
new file mode 100644
index 000000000..86d074d21
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/test.ts
@@ -0,0 +1,52 @@
+export {};
+
+declare function get<T>(): T;
+
+const foo = 'foo';
+
+({
+    x: 1,
+    ...{x: 2, y: 2},
+    y: 1,
+    ...{x: 3},
+});
+
+({
+    foo,
+    ...{foo},
+});
+
+({
+    [foo]: 1,
+    ...{[foo]: 2},
+});
+
+({
+    [Symbol.iterator]: 1,
+    ...{[Symbol.iterator]: 2},
+});
+
+({
+    [get<string>()]: 1,
+    ...{[get<string>()]: 2},
+});
+
+({
+    [get<'foo'>()]: 1,
+    ...{[get<'foo'>()]: 2},
+    ...{[foo]: 3},
+});
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    ...get<{foo?: string, bar: number, baz: any}>(),
+});
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    ...get<{foo: string, bar: number} | {bar: number, baz: boolean}>(),
+});
diff --git a/packages/mimir/test/no-useless-object-property/tsconfig.json b/packages/mimir/test/no-useless-object-property/tsconfig.json
new file mode 100644
index 000000000..3338b50e9
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/tsconfig.json
@@ -0,0 +1,6 @@
+{
+  "compilerOptions": {
+    "strict": true,
+    "target": "esnext"
+  }
+}

From 613a69b427691992753a3c265bd6d60d759210d2 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 12 Apr 2018 20:14:15 +0200
Subject: [PATCH 2/9] make it work with unions and well known symbols

---
 .../default/test.ts.lint                      |  5 ++-
 .../src/rules/no-useless-object-property.ts   | 40 ++++++++++++-------
 .../test/no-useless-object-property/test.ts   |  4 +-
 3 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
index 653dc2f43..ae5bb2c71 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
@@ -26,6 +26,7 @@ const foo = 'foo';
 });
 
 ({
+    '__@iterator': 1,
     [Symbol.iterator]: 1,
     ~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
     ...{[Symbol.iterator]: 2},
@@ -54,6 +55,8 @@ const foo = 'foo';
 ({
     foo: 1,
     bar: 1,
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
     baz: 1,
-    ...get<{foo: string, bar: number} | {bar: number, baz: boolean}>(),
+    bas: 1,
+    ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
 });
diff --git a/packages/mimir/src/rules/no-useless-object-property.ts b/packages/mimir/src/rules/no-useless-object-property.ts
index 950ecc731..4e24530c0 100644
--- a/packages/mimir/src/rules/no-useless-object-property.ts
+++ b/packages/mimir/src/rules/no-useless-object-property.ts
@@ -1,6 +1,6 @@
 import { TypedRule, excludeDeclarationFiles } from '@fimbul/ymir';
 import * as ts from 'typescript';
-import { isReassignmentTarget, getPropertyName, isObjectType, unionTypeParts } from 'tsutils';
+import { isReassignmentTarget, isObjectType, unionTypeParts } from 'tsutils';
 
 @excludeDeclarationFiles
 export class Rule extends TypedRule {
@@ -19,7 +19,7 @@ export class Rule extends TypedRule {
     }
 
     private checkObject({properties}: ts.ObjectLiteralExpression) {
-        const propertiesSeen = new Set<string>();
+        const propertiesSeen = new Set<ts.__String>();
         for (let i = properties.length - 1; i >= 0; --i) {
             const info = this.getPropertyInfo(properties[i]);
             if (info.known && info.names.every((name) => propertiesSeen.has(name)))
@@ -36,12 +36,11 @@ export class Rule extends TypedRule {
             case ts.SyntaxKind.ShorthandPropertyAssignment:
                 return {
                     known: true,
-                    names: [property.name.text],
-                    assignedNames: [property.name.text],
+                    names: [property.name.escapedText],
+                    assignedNames: [property.name.escapedText],
                 };
             default: {
-                const name = getPropertyName(property.name) ||
-                    getNameOfSymbol(this.checker.getSymbolAtLocation(property.name));
+                const name = this.getPropertyName(property.name);
                 if (name === undefined)
                     return {
                         known: false,
@@ -57,8 +56,17 @@ export class Rule extends TypedRule {
         }
     }
 
+    private getPropertyName(node: ts.PropertyName): ts.__String | undefined {
+        const symbol = this.checker.getSymbolAtLocation(node);
+        return symbol && symbol.escapedName;
+    }
+
     private getPropertyInfoFromSpread(node: ts.Expression): PropertyInfo {
         const type = this.checker.getTypeAtLocation(node);
+        return unionTypeParts(type).map((t) => this.getPropertyInfoFromType(t, node)).reduce(combinePropertyInfo);
+    }
+
+    private getPropertyInfoFromType(type: ts.Type, node: ts.Expression): PropertyInfo {
         if (!isObjectType(type))
             return {
                 known: false,
@@ -73,23 +81,27 @@ export class Rule extends TypedRule {
         };
         for (const prop of type.getProperties()) {
             if (!unionTypeParts(this.checker.getTypeOfSymbolAtLocation(prop, node)).some(isOptionalType))
-                result.assignedNames.push(prop.name);
-            result.names.push(prop.name);
+                result.assignedNames.push(prop.escapedName);
+            result.names.push(prop.escapedName);
         }
         return result;
     }
 }
 
-function isOptionalType(type: ts.Type) {
-    return (type.flags & (ts.TypeFlags.Undefined | ts.TypeFlags.Any)) !== 0;
+function combinePropertyInfo(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 getNameOfSymbol(symbol: ts.Symbol | undefined) {
-    return symbol && symbol.name;
+function isOptionalType(type: ts.Type) {
+    return (type.flags & (ts.TypeFlags.Undefined | ts.TypeFlags.Any)) !== 0;
 }
 
 interface PropertyInfo {
     known: boolean;
-    names: string[];
-    assignedNames: string[];
+    names: ts.__String[];
+    assignedNames: ts.__String[];
 }
diff --git a/packages/mimir/test/no-useless-object-property/test.ts b/packages/mimir/test/no-useless-object-property/test.ts
index 86d074d21..3b26033dd 100644
--- a/packages/mimir/test/no-useless-object-property/test.ts
+++ b/packages/mimir/test/no-useless-object-property/test.ts
@@ -22,6 +22,7 @@ const foo = 'foo';
 });
 
 ({
+    '__@iterator': 1,
     [Symbol.iterator]: 1,
     ...{[Symbol.iterator]: 2},
 });
@@ -48,5 +49,6 @@ const foo = 'foo';
     foo: 1,
     bar: 1,
     baz: 1,
-    ...get<{foo: string, bar: number} | {bar: number, baz: boolean}>(),
+    bas: 1,
+    ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
 });

From f2ed567055f0e284275584d06a64dc032b6061e5 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 12 Apr 2018 20:29:30 +0200
Subject: [PATCH 3/9] add baselines for older typescript versions

---
 .../pre260/test.ts.lint                       | 56 +++++++++++++++++
 .../ts260/test.ts.lint                        | 60 +++++++++++++++++++
 .../default.test.json                         |  4 +-
 .../pre260.test.json                          |  3 +
 .../ts260.test.json                           |  3 +
 5 files changed, 125 insertions(+), 1 deletion(-)
 create mode 100644 baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
 create mode 100644 baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
 create mode 100644 packages/mimir/test/no-useless-object-property/pre260.test.json
 create mode 100644 packages/mimir/test/no-useless-object-property/ts260.test.json

diff --git a/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
new file mode 100644
index 000000000..c8dafd55e
--- /dev/null
+++ b/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
@@ -0,0 +1,56 @@
+export {};
+
+declare function get<T>(): T;
+
+const foo = 'foo';
+
+({
+    x: 1,
+    ...{x: 2, y: 2},
+    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    y: 1,
+    ...{x: 3},
+});
+
+({
+    foo,
+    ~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{foo},
+});
+
+({
+    [foo]: 1,
+    ...{[foo]: 2},
+});
+
+({
+    '__@iterator': 1,
+    [Symbol.iterator]: 1,
+    ...{[Symbol.iterator]: 2},
+});
+
+({
+    [get<string>()]: 1,
+    ...{[get<string>()]: 2},
+});
+
+({
+    [get<'foo'>()]: 1,
+    ...{[get<'foo'>()]: 2},
+    ...{[foo]: 3},
+});
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    ...get<{foo?: string, bar: number, baz: any}>(),
+});
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    bas: 1,
+    ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
+});
diff --git a/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
new file mode 100644
index 000000000..b952a5958
--- /dev/null
+++ b/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
@@ -0,0 +1,60 @@
+export {};
+
+declare function get<T>(): T;
+
+const foo = 'foo';
+
+({
+    x: 1,
+    ~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{x: 2, y: 2},
+    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    y: 1,
+    ...{x: 3},
+});
+
+({
+    foo,
+    ~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{foo},
+});
+
+({
+    [foo]: 1,
+    ...{[foo]: 2},
+});
+
+({
+    '__@iterator': 1,
+    [Symbol.iterator]: 1,
+    ...{[Symbol.iterator]: 2},
+});
+
+({
+    [get<string>()]: 1,
+    ...{[get<string>()]: 2},
+});
+
+({
+    [get<'foo'>()]: 1,
+    ...{[get<'foo'>()]: 2},
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{[foo]: 3},
+});
+
+({
+    foo: 1,
+    bar: 1,
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    baz: 1,
+    ...get<{foo?: string, bar: number, baz: any}>(),
+});
+
+({
+    foo: 1,
+    bar: 1,
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    baz: 1,
+    bas: 1,
+    ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
+});
diff --git a/packages/mimir/test/no-useless-object-property/default.test.json b/packages/mimir/test/no-useless-object-property/default.test.json
index 0967ef424..92b4d9e1c 100644
--- a/packages/mimir/test/no-useless-object-property/default.test.json
+++ b/packages/mimir/test/no-useless-object-property/default.test.json
@@ -1 +1,3 @@
-{}
+{
+  "typescriptVersion": ">= 2.7.0"
+}
diff --git a/packages/mimir/test/no-useless-object-property/pre260.test.json b/packages/mimir/test/no-useless-object-property/pre260.test.json
new file mode 100644
index 000000000..44754ce9a
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/pre260.test.json
@@ -0,0 +1,3 @@
+{
+  "typescriptVersion": "<2.6.0"
+}
diff --git a/packages/mimir/test/no-useless-object-property/ts260.test.json b/packages/mimir/test/no-useless-object-property/ts260.test.json
new file mode 100644
index 000000000..3ab0610ff
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/ts260.test.json
@@ -0,0 +1,3 @@
+{
+  "typescriptVersion": "~2.6.0"
+}

From 88a26a84ac42337293ea747cdbeaa6df9c759ef6 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 12 Apr 2018 20:31:58 +0200
Subject: [PATCH 4/9] Add docs

---
 packages/mimir/README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/mimir/README.md b/packages/mimir/README.md
index f7d659eb2..b5f7da1cb 100644
--- a/packages/mimir/README.md
+++ b/packages/mimir/README.md
@@ -41,6 +41,7 @@ Rule | Description | Difference to TSLint rule / Why you should use it
 `no-useless-assertion` | Detects type assertions that don't change the type or are not necessary in the first place. *requires type information* | TSLint's `no-unnecessary-type-assertion` does not detect assertions needed to silence the compiler warning `Variable ... is used before being assigned.` The Wotan builtin rule also checks whether the assertion is necessary at all or the receiver accepts the original type.
 `no-useless-initializer` | Detects unnecessary initialization with `undefined` and destructuring defaults (*requires type information*). | TSLint's rule `no-unnecessary-initializer` doesn't fix all parameter initializers and gives false positives for destructuring.
 `no-useless-jump-label` | Detects `continue label;` and `break label;` where the label is not necessary. | There's no similar TSLint rule.
+`no-useless-object-property` | Detects properties in object literals that are overridden by a spreaded object. | TSLint has no such rule.
 `no-useless-predicate` | Detects redundant conditions that are either always true or always false. *requires type information* | Combination of TSLint's `strict-type-predicates`, `typeof-compare` and parts of `strict-boolean-expressions`.
 `no-useless-spread` | Detects redundant array and object spread which can safely be removed. | There's no similar TSLint rule.
 `prefer-const` | Prefer `const` for variables that are never reassigned. Use option `{destructuring: "any"}` if you want to see failures for each identifier of a destructuring, even if not all of them can be constants. The default is `{destructuring: "all"}`. | TSLint's `prefer-const` rule gives some false positives for merged declarations and variables used in before being declared which results in a compiler error after fixing.

From 198ae2321451b462869cfa282319b1256567e34d Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 12 Apr 2018 20:57:29 +0200
Subject: [PATCH 5/9] some cleanup and fixup

---
 .../default/test.ts.lint                      |  4 +-
 .../loose/test.ts.lint                        | 64 +++++++++++++++
 .../pre260/test.ts.lint                       |  5 +-
 .../ts260/test.ts.lint                        |  4 +-
 packages/mimir/recommended.yaml               |  1 +
 .../src/rules/no-useless-object-property.ts   | 81 +++++++++----------
 .../loose.test.json                           |  4 +
 .../test/no-useless-object-property/test.ts   |  3 +-
 .../tsconfig-loose.json                       |  6 ++
 9 files changed, 122 insertions(+), 50 deletions(-)
 create mode 100644 baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
 create mode 100644 packages/mimir/test/no-useless-object-property/loose.test.json
 create mode 100644 packages/mimir/test/no-useless-object-property/tsconfig-loose.json

diff --git a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
index ae5bb2c71..9cbed06de 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
@@ -49,7 +49,8 @@ const foo = 'foo';
     bar: 1,
     ~~~~~~  [error no-useless-object-property: Property is overridden later.]
     baz: 1,
-    ...get<{foo?: string, bar: number, baz: any}>(),
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
 });
 
 ({
@@ -59,4 +60,5 @@ const foo = 'foo';
     baz: 1,
     bas: 1,
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
+    ...Boolean() && {foo},
 });
diff --git a/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
new file mode 100644
index 000000000..9cbed06de
--- /dev/null
+++ b/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
@@ -0,0 +1,64 @@
+export {};
+
+declare function get<T>(): T;
+
+const foo = 'foo';
+
+({
+    x: 1,
+    ~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{x: 2, y: 2},
+    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    y: 1,
+    ...{x: 3},
+});
+
+({
+    foo,
+    ~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{foo},
+});
+
+({
+    [foo]: 1,
+    ~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{[foo]: 2},
+});
+
+({
+    '__@iterator': 1,
+    [Symbol.iterator]: 1,
+    ~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{[Symbol.iterator]: 2},
+});
+
+({
+    [get<string>()]: 1,
+    ...{[get<string>()]: 2},
+});
+
+({
+    [get<'foo'>()]: 1,
+    ...{[get<'foo'>()]: 2},
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...{[foo]: 3},
+});
+
+({
+    foo: 1,
+    bar: 1,
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    baz: 1,
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
+});
+
+({
+    foo: 1,
+    bar: 1,
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    baz: 1,
+    bas: 1,
+    ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
+    ...Boolean() && {foo},
+});
diff --git a/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
index c8dafd55e..2691534a3 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
@@ -7,14 +7,12 @@ const foo = 'foo';
 ({
     x: 1,
     ...{x: 2, y: 2},
-    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
     y: 1,
     ...{x: 3},
 });
 
 ({
     foo,
-    ~~~  [error no-useless-object-property: Property is overridden later.]
     ...{foo},
 });
 
@@ -44,7 +42,7 @@ const foo = 'foo';
     foo: 1,
     bar: 1,
     baz: 1,
-    ...get<{foo?: string, bar: number, baz: any}>(),
+    ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
 });
 
 ({
@@ -53,4 +51,5 @@ const foo = 'foo';
     baz: 1,
     bas: 1,
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
+    ...Boolean() && {foo},
 });
diff --git a/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
index b952a5958..3c1668ec7 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
@@ -47,7 +47,8 @@ const foo = 'foo';
     bar: 1,
     ~~~~~~  [error no-useless-object-property: Property is overridden later.]
     baz: 1,
-    ...get<{foo?: string, bar: number, baz: any}>(),
+    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
 });
 
 ({
@@ -57,4 +58,5 @@ const foo = 'foo';
     baz: 1,
     bas: 1,
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
+    ...Boolean() && {foo},
 });
diff --git a/packages/mimir/recommended.yaml b/packages/mimir/recommended.yaml
index 2d990e8a1..74ec4a7c2 100644
--- a/packages/mimir/recommended.yaml
+++ b/packages/mimir/recommended.yaml
@@ -21,6 +21,7 @@ rules:
   no-useless-assertion: error
   no-useless-initializer: error
   no-useless-jump-label: error
+  no-useless-object-property: error
   no-useless-predicate: error
   no-useless-spread: error
   prefer-const: error
diff --git a/packages/mimir/src/rules/no-useless-object-property.ts b/packages/mimir/src/rules/no-useless-object-property.ts
index 4e24530c0..ca7b56683 100644
--- a/packages/mimir/src/rules/no-useless-object-property.ts
+++ b/packages/mimir/src/rules/no-useless-object-property.ts
@@ -2,8 +2,24 @@ import { TypedRule, excludeDeclarationFiles } from '@fimbul/ymir';
 import * as ts from 'typescript';
 import { isReassignmentTarget, isObjectType, unionTypeParts } from 'tsutils';
 
+interface PropertyInfo {
+    known: boolean;
+    names: ts.__String[];
+    assignedNames: ts.__String[];
+}
+
+const emptyPropertyInfo: PropertyInfo = {
+    known: false,
+    names: [],
+    assignedNames: [],
+};
+
 @excludeDeclarationFiles
 export class Rule extends TypedRule {
+    public static supports() {
+        return !ts.version.startsWith('2.4.');
+    }
+
     public apply() {
         const checkedObjects = new Set<number>();
         for (const node of this.context.getFlatAst()) {
@@ -40,52 +56,39 @@ export class Rule extends TypedRule {
                     assignedNames: [property.name.escapedText],
                 };
             default: {
-                const name = this.getPropertyName(property.name);
-                if (name === undefined)
-                    return {
-                        known: false,
-                        names: [],
-                        assignedNames: [],
-                    };
+                const symbol = this.checker.getSymbolAtLocation(property.name);
+                if (symbol === undefined)
+                    return emptyPropertyInfo;
                 return {
                     known: true,
-                    names: [name],
-                    assignedNames: [name],
+                    names: [symbol.escapedName],
+                    assignedNames: [symbol.escapedName],
                 };
             }
         }
     }
 
-    private getPropertyName(node: ts.PropertyName): ts.__String | undefined {
-        const symbol = this.checker.getSymbolAtLocation(node);
-        return symbol && symbol.escapedName;
-    }
-
     private getPropertyInfoFromSpread(node: ts.Expression): PropertyInfo {
         const type = this.checker.getTypeAtLocation(node);
-        return unionTypeParts(type).map((t) => this.getPropertyInfoFromType(t, node)).reduce(combinePropertyInfo);
+        return unionTypeParts(type).map(getPropertyInfoFromType).reduce(combinePropertyInfo);
     }
 
-    private getPropertyInfoFromType(type: ts.Type, node: ts.Expression): PropertyInfo {
-        if (!isObjectType(type))
-            return {
-                known: false,
-                names: [],
-                assignedNames: [],
-            };
-        const result: PropertyInfo = {
-            known: (type.flags & ts.TypeFlags.Any) !== 0 ||
-                type.getStringIndexType() === undefined && type.getNumberIndexType() === undefined,
-            names: [],
-            assignedNames: [],
-        };
-        for (const prop of type.getProperties()) {
-            if (!unionTypeParts(this.checker.getTypeOfSymbolAtLocation(prop, node)).some(isOptionalType))
-                result.assignedNames.push(prop.escapedName);
-            result.names.push(prop.escapedName);
-        }
-        return result;
+}
+function getPropertyInfoFromType(type: ts.Type): PropertyInfo {
+    if (!isObjectType(type))
+        return emptyPropertyInfo;
+    const result: PropertyInfo = {
+        known: (type.flags & ts.TypeFlags.Any) !== 0 ||
+            type.getStringIndexType() === undefined && type.getNumberIndexType() === undefined,
+        names: [],
+        assignedNames: [],
+    };
+    for (const prop of type.getProperties()) {
+        if ((prop.flags & ts.SymbolFlags.Optional) === 0)
+            result.assignedNames.push(prop.escapedName);
+        result.names.push(prop.escapedName);
     }
+    return result;
 }
 
 function combinePropertyInfo(a: PropertyInfo, b: PropertyInfo): PropertyInfo {
@@ -95,13 +98,3 @@ function combinePropertyInfo(a: PropertyInfo, b: PropertyInfo): PropertyInfo {
         assignedNames: a.assignedNames.filter((name) => b.assignedNames.includes(name)),
     };
 }
-
-function isOptionalType(type: ts.Type) {
-    return (type.flags & (ts.TypeFlags.Undefined | ts.TypeFlags.Any)) !== 0;
-}
-
-interface PropertyInfo {
-    known: boolean;
-    names: ts.__String[];
-    assignedNames: ts.__String[];
-}
diff --git a/packages/mimir/test/no-useless-object-property/loose.test.json b/packages/mimir/test/no-useless-object-property/loose.test.json
new file mode 100644
index 000000000..92781ebd9
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/loose.test.json
@@ -0,0 +1,4 @@
+{
+  "typescriptVersion": ">= 2.7.0",
+  "project": "tsconfig-loose.json"
+}
diff --git a/packages/mimir/test/no-useless-object-property/test.ts b/packages/mimir/test/no-useless-object-property/test.ts
index 3b26033dd..2691534a3 100644
--- a/packages/mimir/test/no-useless-object-property/test.ts
+++ b/packages/mimir/test/no-useless-object-property/test.ts
@@ -42,7 +42,7 @@ const foo = 'foo';
     foo: 1,
     bar: 1,
     baz: 1,
-    ...get<{foo?: string, bar: number, baz: any}>(),
+    ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
 });
 
 ({
@@ -51,4 +51,5 @@ const foo = 'foo';
     baz: 1,
     bas: 1,
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
+    ...Boolean() && {foo},
 });
diff --git a/packages/mimir/test/no-useless-object-property/tsconfig-loose.json b/packages/mimir/test/no-useless-object-property/tsconfig-loose.json
new file mode 100644
index 000000000..04608d4ca
--- /dev/null
+++ b/packages/mimir/test/no-useless-object-property/tsconfig-loose.json
@@ -0,0 +1,6 @@
+{
+  "compilerOptions": {
+    "strict": false,
+    "target": "esnext"
+  }
+}

From 91df02a4f8a48d299e7d9dff3eae5b5107d69057 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 12 Apr 2018 21:33:09 +0200
Subject: [PATCH 6/9] require strictNullChecks

---
 .../test/no-useless-object-property/loose/test.ts.lint   | 9 ---------
 packages/mimir/src/rules/no-useless-object-property.ts   | 7 ++++---
 .../test/no-useless-object-property/loose.test.json      | 1 -
 3 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
index 9cbed06de..2691534a3 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
@@ -6,29 +6,24 @@ const foo = 'foo';
 
 ({
     x: 1,
-    ~~~~  [error no-useless-object-property: Property is overridden later.]
     ...{x: 2, y: 2},
-    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
     y: 1,
     ...{x: 3},
 });
 
 ({
     foo,
-    ~~~  [error no-useless-object-property: Property is overridden later.]
     ...{foo},
 });
 
 ({
     [foo]: 1,
-    ~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
     ...{[foo]: 2},
 });
 
 ({
     '__@iterator': 1,
     [Symbol.iterator]: 1,
-    ~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
     ...{[Symbol.iterator]: 2},
 });
 
@@ -40,23 +35,19 @@ const foo = 'foo';
 ({
     [get<'foo'>()]: 1,
     ...{[get<'foo'>()]: 2},
-    ~~~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
     ...{[foo]: 3},
 });
 
 ({
     foo: 1,
     bar: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
     baz: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
     ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
 });
 
 ({
     foo: 1,
     bar: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
     baz: 1,
     bas: 1,
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
diff --git a/packages/mimir/src/rules/no-useless-object-property.ts b/packages/mimir/src/rules/no-useless-object-property.ts
index ca7b56683..18e7bd44a 100644
--- a/packages/mimir/src/rules/no-useless-object-property.ts
+++ b/packages/mimir/src/rules/no-useless-object-property.ts
@@ -1,6 +1,7 @@
-import { TypedRule, excludeDeclarationFiles } from '@fimbul/ymir';
+import { TypedRule, excludeDeclarationFiles, RuleSupportsContext } from '@fimbul/ymir';
 import * as ts from 'typescript';
 import { isReassignmentTarget, isObjectType, unionTypeParts } from 'tsutils';
+import { isStrictNullChecksEnabled } from '../utils';
 
 interface PropertyInfo {
     known: boolean;
@@ -16,8 +17,8 @@ const emptyPropertyInfo: PropertyInfo = {
 
 @excludeDeclarationFiles
 export class Rule extends TypedRule {
-    public static supports() {
-        return !ts.version.startsWith('2.4.');
+    public static supports(_sourceFile: ts.SourceFile, context: RuleSupportsContext) {
+        return !ts.version.startsWith('2.4.') && isStrictNullChecksEnabled(context.program!.getCompilerOptions());
     }
 
     public apply() {
diff --git a/packages/mimir/test/no-useless-object-property/loose.test.json b/packages/mimir/test/no-useless-object-property/loose.test.json
index 92781ebd9..44860f0aa 100644
--- a/packages/mimir/test/no-useless-object-property/loose.test.json
+++ b/packages/mimir/test/no-useless-object-property/loose.test.json
@@ -1,4 +1,3 @@
 {
-  "typescriptVersion": ">= 2.7.0",
   "project": "tsconfig-loose.json"
 }

From 65af5a54c4d0f519e61ad73e8d2617be82dbf716 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 12 Apr 2018 21:43:45 +0200
Subject: [PATCH 7/9] add test for destructuring

---
 .../test/no-useless-object-property/default/test.ts.lint     | 5 +++++
 .../mimir/test/no-useless-object-property/loose/test.ts.lint | 5 +++++
 .../test/no-useless-object-property/pre260/test.ts.lint      | 5 +++++
 .../mimir/test/no-useless-object-property/ts260/test.ts.lint | 5 +++++
 packages/mimir/test/no-useless-object-property/test.ts       | 5 +++++
 5 files changed, 25 insertions(+)

diff --git a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
index 9cbed06de..87454e10c 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
@@ -62,3 +62,8 @@ const foo = 'foo';
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
     ...Boolean() && {foo},
 });
+
+{
+    let a, b;
+    ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
+}
diff --git a/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
index 2691534a3..44944bb71 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
@@ -53,3 +53,8 @@ const foo = 'foo';
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
     ...Boolean() && {foo},
 });
+
+{
+    let a, b;
+    ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
+}
diff --git a/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
index 2691534a3..44944bb71 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
@@ -53,3 +53,8 @@ const foo = 'foo';
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
     ...Boolean() && {foo},
 });
+
+{
+    let a, b;
+    ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
+}
diff --git a/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint b/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
index 3c1668ec7..f1465aab3 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
+++ b/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
@@ -60,3 +60,8 @@ const foo = 'foo';
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
     ...Boolean() && {foo},
 });
+
+{
+    let a, b;
+    ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
+}
diff --git a/packages/mimir/test/no-useless-object-property/test.ts b/packages/mimir/test/no-useless-object-property/test.ts
index 2691534a3..44944bb71 100644
--- a/packages/mimir/test/no-useless-object-property/test.ts
+++ b/packages/mimir/test/no-useless-object-property/test.ts
@@ -53,3 +53,8 @@ const foo = 'foo';
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
     ...Boolean() && {foo},
 });
+
+{
+    let a, b;
+    ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
+}

From 6821e403fce6819d210040022a792886fce628b9 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 26 Apr 2018 22:14:25 +0200
Subject: [PATCH 8/9] rename all the things

---
 .../default/test.ts.lint                       | 18 +++++++++---------
 .../loose/test.ts.lint                         |  0
 .../pre260/test.ts.lint                        |  0
 .../ts260/test.ts.lint                         | 14 +++++++-------
 packages/mimir/README.md                       |  2 +-
 packages/mimir/recommended.yaml                |  2 +-
 ...erty.ts => no-duplicate-spread-property.ts} | 11 ++++++++++-
 .../no-duplicate-spread-property/.wotanrc.yaml |  2 ++
 .../default.test.json                          |  0
 .../loose.test.json                            |  0
 .../pre260.test.json                           |  0
 .../test.ts                                    |  0
 .../ts260.test.json                            |  0
 .../tsconfig-loose.json                        |  0
 .../tsconfig.json                              |  0
 .../no-useless-object-property/.wotanrc.yaml   |  2 --
 16 files changed, 30 insertions(+), 21 deletions(-)
 rename baselines/packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/default/test.ts.lint (55%)
 rename baselines/packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/loose/test.ts.lint (100%)
 rename baselines/packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/pre260/test.ts.lint (100%)
 rename baselines/packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/ts260/test.ts.lint (58%)
 rename packages/mimir/src/rules/{no-useless-object-property.ts => no-duplicate-spread-property.ts} (88%)
 create mode 100644 packages/mimir/test/no-duplicate-spread-property/.wotanrc.yaml
 rename packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/default.test.json (100%)
 rename packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/loose.test.json (100%)
 rename packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/pre260.test.json (100%)
 rename packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/test.ts (100%)
 rename packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/ts260.test.json (100%)
 rename packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/tsconfig-loose.json (100%)
 rename packages/mimir/test/{no-useless-object-property => no-duplicate-spread-property}/tsconfig.json (100%)
 delete mode 100644 packages/mimir/test/no-useless-object-property/.wotanrc.yaml

diff --git a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint
similarity index 55%
rename from baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
rename to baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint
index 87454e10c..d8512b09e 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/default/test.ts.lint
+++ b/baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint
@@ -6,29 +6,29 @@ const foo = 'foo';
 
 ({
     x: 1,
-    ~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{x: 2, y: 2},
-    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     y: 1,
     ...{x: 3},
 });
 
 ({
     foo,
-    ~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{foo},
 });
 
 ({
     [foo]: 1,
-    ~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{[foo]: 2},
 });
 
 ({
     '__@iterator': 1,
     [Symbol.iterator]: 1,
-    ~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{[Symbol.iterator]: 2},
 });
 
@@ -40,23 +40,23 @@ const foo = 'foo';
 ({
     [get<'foo'>()]: 1,
     ...{[get<'foo'>()]: 2},
-    ~~~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{[foo]: 3},
 });
 
 ({
     foo: 1,
     bar: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     baz: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
 });
 
 ({
     foo: 1,
     bar: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     baz: 1,
     bas: 1,
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
diff --git a/baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/loose/test.ts.lint
similarity index 100%
rename from baselines/packages/mimir/test/no-useless-object-property/loose/test.ts.lint
rename to baselines/packages/mimir/test/no-duplicate-spread-property/loose/test.ts.lint
diff --git a/baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/pre260/test.ts.lint
similarity index 100%
rename from baselines/packages/mimir/test/no-useless-object-property/pre260/test.ts.lint
rename to baselines/packages/mimir/test/no-duplicate-spread-property/pre260/test.ts.lint
diff --git a/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/ts260/test.ts.lint
similarity index 58%
rename from baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
rename to baselines/packages/mimir/test/no-duplicate-spread-property/ts260/test.ts.lint
index f1465aab3..df99cc57e 100644
--- a/baselines/packages/mimir/test/no-useless-object-property/ts260/test.ts.lint
+++ b/baselines/packages/mimir/test/no-duplicate-spread-property/ts260/test.ts.lint
@@ -6,16 +6,16 @@ const foo = 'foo';
 
 ({
     x: 1,
-    ~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{x: 2, y: 2},
-    ~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     y: 1,
     ...{x: 3},
 });
 
 ({
     foo,
-    ~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{foo},
 });
 
@@ -38,23 +38,23 @@ const foo = 'foo';
 ({
     [get<'foo'>()]: 1,
     ...{[get<'foo'>()]: 2},
-    ~~~~~~~~~~~~~~~~~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...{[foo]: 3},
 });
 
 ({
     foo: 1,
     bar: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     baz: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     ...get<{foo?: string, bar: number, baz: boolean | undefined}>(),
 });
 
 ({
     foo: 1,
     bar: 1,
-    ~~~~~~  [error no-useless-object-property: Property is overridden later.]
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
     baz: 1,
     bas: 1,
     ...get<{foo: string, bar: number, bas: number} | {bar: number, baz: boolean, bas?: number}>(),
diff --git a/packages/mimir/README.md b/packages/mimir/README.md
index 645c146b1..a283ce35c 100644
--- a/packages/mimir/README.md
+++ b/packages/mimir/README.md
@@ -27,6 +27,7 @@ Rule | Description | Difference to TSLint rule / Why you should use it
 `no-case-declaration` | Disallow `let`, `class` and `enum` in case blocks. These are visible within the whole switch statement body but not defined in other case clauses. The compiler currently doesn't warn about such uses. You should use a block to restrict the scope of the declarations. | TSLint has no similar rule, ESLint has `no-case-declarations` which forbids function declarations as well.
 `no-debugger` | Ban `debugger;` statements from your production code. | Performance!
 `no-duplicate-case` | Detects `switch` statements where multiple `case` clauses check for the same value. *uses type information if available* | This implementation tries to infer the value instead of just comparing the source code.
+`no-duplicate-spread-property` | Detects properties in object literals that are overridden by a spreaded object. | TSLint has no such rule.
 `no-fallthrough` | Prevents unintentional fallthough in `switch` statements from one case to another. If the fallthrough is intended, add a comment that matches `/^\s*falls? ?through\b/i`. | Allows more comment variants such as `fallthrough` or `fall through`.
 `no-inferred-empty-object` | Warns if a type parameter is inferred as `{}` because the compiler cannot find any inference site. *requires type information* | Really checks every type parameter of function, method and constructor calls. Correctly handles type parameters from JSDoc comments. Recognises type parameter defaults on all merged declarations.
 `no-invalid-assertion` | Disallows asserting a literal type to a different literal type of the same widened type, e.g. `'foo' as 'bar'`. *requires type information* | TSLint has no similar rule.
@@ -42,7 +43,6 @@ Rule | Description | Difference to TSLint rule / Why you should use it
 `no-useless-assertion` | Detects type assertions that don't change the type or are not necessary in the first place. *requires type information* | TSLint's `no-unnecessary-type-assertion` does not detect assertions needed to silence the compiler warning `Variable ... is used before being assigned.` The Wotan builtin rule also checks whether the assertion is necessary at all or the receiver accepts the original type.
 `no-useless-initializer` | Detects unnecessary initialization with `undefined` and destructuring defaults (*requires type information*). | TSLint's rule `no-unnecessary-initializer` doesn't fix all parameter initializers and gives false positives for destructuring.
 `no-useless-jump-label` | Detects `continue label;` and `break label;` where the label is not necessary. | There's no similar TSLint rule.
-`no-useless-object-property` | Detects properties in object literals that are overridden by a spreaded object. | TSLint has no such rule.
 `no-useless-predicate` | Detects redundant conditions that are either always true or always false. *requires type information* | Combination of TSLint's `strict-type-predicates`, `typeof-compare` and parts of `strict-boolean-expressions`.
 `no-useless-spread` | Detects redundant array and object spread which can safely be removed. | There's no similar TSLint rule.
 `prefer-const` | Prefer `const` for variables that are never reassigned. Use option `{destructuring: "any"}` if you want to see failures for each identifier of a destructuring, even if not all of them can be constants. The default is `{destructuring: "all"}`. | TSLint's `prefer-const` rule gives some false positives for merged declarations and variables used in before being declared which results in a compiler error after fixing.
diff --git a/packages/mimir/recommended.yaml b/packages/mimir/recommended.yaml
index c082aa11d..c3e0b3702 100644
--- a/packages/mimir/recommended.yaml
+++ b/packages/mimir/recommended.yaml
@@ -7,6 +7,7 @@ rules:
   no-case-declaration: error
   no-debugger: error
   no-duplicate-case: error
+  no-duplicate-spread-property: error
   no-fallthrough: error
   no-inferred-empty-object: error
   no-invalid-assertion: error
@@ -22,7 +23,6 @@ rules:
   no-useless-assertion: error
   no-useless-initializer: error
   no-useless-jump-label: error
-  no-useless-object-property: error
   no-useless-predicate: error
   no-useless-spread: error
   prefer-const: error
diff --git a/packages/mimir/src/rules/no-useless-object-property.ts b/packages/mimir/src/rules/no-duplicate-spread-property.ts
similarity index 88%
rename from packages/mimir/src/rules/no-useless-object-property.ts
rename to packages/mimir/src/rules/no-duplicate-spread-property.ts
index 18e7bd44a..de4533080 100644
--- a/packages/mimir/src/rules/no-useless-object-property.ts
+++ b/packages/mimir/src/rules/no-duplicate-spread-property.ts
@@ -1,6 +1,6 @@
 import { TypedRule, excludeDeclarationFiles, RuleSupportsContext } from '@fimbul/ymir';
 import * as ts from 'typescript';
-import { isReassignmentTarget, isObjectType, unionTypeParts } from 'tsutils';
+import { isReassignmentTarget, isObjectType, unionTypeParts, isClassLikeDeclaration } from 'tsutils';
 import { isStrictNullChecksEnabled } from '../utils';
 
 interface PropertyInfo {
@@ -85,12 +85,21 @@ function getPropertyInfoFromType(type: ts.Type): PropertyInfo {
         assignedNames: [],
     };
     for (const prop of type.getProperties()) {
+        if (isClassMethod(prop))
+            continue;
         if ((prop.flags & ts.SymbolFlags.Optional) === 0)
             result.assignedNames.push(prop.escapedName);
         result.names.push(prop.escapedName);
     }
     return result;
 }
+function isClassMethod(prop: ts.Symbol): boolean | undefined {
+    if (prop.flags & ts.SymbolFlags.Method && prop.declarations !== undefined)
+        for (const declaration of prop.declarations)
+            if (isClassLikeDeclaration(declaration.parent!))
+                return true;
+    return false;
+}
 
 function combinePropertyInfo(a: PropertyInfo, b: PropertyInfo): PropertyInfo {
     return {
diff --git a/packages/mimir/test/no-duplicate-spread-property/.wotanrc.yaml b/packages/mimir/test/no-duplicate-spread-property/.wotanrc.yaml
new file mode 100644
index 000000000..c76b77fcf
--- /dev/null
+++ b/packages/mimir/test/no-duplicate-spread-property/.wotanrc.yaml
@@ -0,0 +1,2 @@
+rules:
+  no-duplicate-spread-property: error
diff --git a/packages/mimir/test/no-useless-object-property/default.test.json b/packages/mimir/test/no-duplicate-spread-property/default.test.json
similarity index 100%
rename from packages/mimir/test/no-useless-object-property/default.test.json
rename to packages/mimir/test/no-duplicate-spread-property/default.test.json
diff --git a/packages/mimir/test/no-useless-object-property/loose.test.json b/packages/mimir/test/no-duplicate-spread-property/loose.test.json
similarity index 100%
rename from packages/mimir/test/no-useless-object-property/loose.test.json
rename to packages/mimir/test/no-duplicate-spread-property/loose.test.json
diff --git a/packages/mimir/test/no-useless-object-property/pre260.test.json b/packages/mimir/test/no-duplicate-spread-property/pre260.test.json
similarity index 100%
rename from packages/mimir/test/no-useless-object-property/pre260.test.json
rename to packages/mimir/test/no-duplicate-spread-property/pre260.test.json
diff --git a/packages/mimir/test/no-useless-object-property/test.ts b/packages/mimir/test/no-duplicate-spread-property/test.ts
similarity index 100%
rename from packages/mimir/test/no-useless-object-property/test.ts
rename to packages/mimir/test/no-duplicate-spread-property/test.ts
diff --git a/packages/mimir/test/no-useless-object-property/ts260.test.json b/packages/mimir/test/no-duplicate-spread-property/ts260.test.json
similarity index 100%
rename from packages/mimir/test/no-useless-object-property/ts260.test.json
rename to packages/mimir/test/no-duplicate-spread-property/ts260.test.json
diff --git a/packages/mimir/test/no-useless-object-property/tsconfig-loose.json b/packages/mimir/test/no-duplicate-spread-property/tsconfig-loose.json
similarity index 100%
rename from packages/mimir/test/no-useless-object-property/tsconfig-loose.json
rename to packages/mimir/test/no-duplicate-spread-property/tsconfig-loose.json
diff --git a/packages/mimir/test/no-useless-object-property/tsconfig.json b/packages/mimir/test/no-duplicate-spread-property/tsconfig.json
similarity index 100%
rename from packages/mimir/test/no-useless-object-property/tsconfig.json
rename to packages/mimir/test/no-duplicate-spread-property/tsconfig.json
diff --git a/packages/mimir/test/no-useless-object-property/.wotanrc.yaml b/packages/mimir/test/no-useless-object-property/.wotanrc.yaml
deleted file mode 100644
index 4792501a3..000000000
--- a/packages/mimir/test/no-useless-object-property/.wotanrc.yaml
+++ /dev/null
@@ -1,2 +0,0 @@
-rules:
-  no-useless-object-property: error

From c5a9108c0da0535c7da65d994353e5429b12117d Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Thu, 26 Apr 2018 22:24:40 +0200
Subject: [PATCH 9/9] add tests with class methods

---
 .../default/test.ts.lint                      | 50 +++++++++++++++++++
 .../loose/test.ts.lint                        | 41 +++++++++++++++
 .../pre260/test.ts.lint                       | 41 +++++++++++++++
 .../ts260/test.ts.lint                        | 50 +++++++++++++++++++
 .../test/no-duplicate-spread-property/test.ts | 41 +++++++++++++++
 5 files changed, 223 insertions(+)

diff --git a/baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint
index d8512b09e..25ad11002 100644
--- a/baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint
+++ b/baselines/packages/mimir/test/no-duplicate-spread-property/default/test.ts.lint
@@ -2,6 +2,12 @@ export {};
 
 declare function get<T>(): T;
 
+declare class WithMethods {
+    foo(): void;
+    bar: () => void;
+    baz: string;
+}
+
 const foo = 'foo';
 
 ({
@@ -67,3 +73,47 @@ const foo = 'foo';
     let a, b;
     ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
 }
+
+({
+    foo: 1,
+    bar: 1,
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    baz: 1,
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    ~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    baz: get<() => void>(),
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    ~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    bar: () => {},
+    ~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    baz: get<() => void>(),
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    ...get<{foo(): void, bar: () => void, baz: number}>(),
+});
+
+({
+    ...get<WithMethods>(),
+    ~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
+
+({
+    ...get<{foo: number, bar: number, baz: number}>(),
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
diff --git a/baselines/packages/mimir/test/no-duplicate-spread-property/loose/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/loose/test.ts.lint
index 44944bb71..d719ed80a 100644
--- a/baselines/packages/mimir/test/no-duplicate-spread-property/loose/test.ts.lint
+++ b/baselines/packages/mimir/test/no-duplicate-spread-property/loose/test.ts.lint
@@ -2,6 +2,12 @@ export {};
 
 declare function get<T>(): T;
 
+declare class WithMethods {
+    foo(): void;
+    bar: () => void;
+    baz: string;
+}
+
 const foo = 'foo';
 
 ({
@@ -58,3 +64,38 @@ const foo = 'foo';
     let a, b;
     ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
 }
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+    ...get<{foo(): void, bar: () => void, baz: number}>(),
+});
+
+({
+    ...get<WithMethods>(),
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
+
+({
+    ...get<{foo: number, bar: number, baz: number}>(),
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
diff --git a/baselines/packages/mimir/test/no-duplicate-spread-property/pre260/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/pre260/test.ts.lint
index 44944bb71..d719ed80a 100644
--- a/baselines/packages/mimir/test/no-duplicate-spread-property/pre260/test.ts.lint
+++ b/baselines/packages/mimir/test/no-duplicate-spread-property/pre260/test.ts.lint
@@ -2,6 +2,12 @@ export {};
 
 declare function get<T>(): T;
 
+declare class WithMethods {
+    foo(): void;
+    bar: () => void;
+    baz: string;
+}
+
 const foo = 'foo';
 
 ({
@@ -58,3 +64,38 @@ const foo = 'foo';
     let a, b;
     ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
 }
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+    ...get<{foo(): void, bar: () => void, baz: number}>(),
+});
+
+({
+    ...get<WithMethods>(),
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
+
+({
+    ...get<{foo: number, bar: number, baz: number}>(),
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
diff --git a/baselines/packages/mimir/test/no-duplicate-spread-property/ts260/test.ts.lint b/baselines/packages/mimir/test/no-duplicate-spread-property/ts260/test.ts.lint
index df99cc57e..d95094a7c 100644
--- a/baselines/packages/mimir/test/no-duplicate-spread-property/ts260/test.ts.lint
+++ b/baselines/packages/mimir/test/no-duplicate-spread-property/ts260/test.ts.lint
@@ -2,6 +2,12 @@ export {};
 
 declare function get<T>(): T;
 
+declare class WithMethods {
+    foo(): void;
+    bar: () => void;
+    baz: string;
+}
+
 const foo = 'foo';
 
 ({
@@ -65,3 +71,47 @@ const foo = 'foo';
     let a, b;
     ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
 }
+
+({
+    foo: 1,
+    bar: 1,
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    baz: 1,
+    ~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    ~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    baz: get<() => void>(),
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    ~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    bar: () => {},
+    ~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    baz: get<() => void>(),
+    ~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    ...get<{foo(): void, bar: () => void, baz: number}>(),
+});
+
+({
+    ...get<WithMethods>(),
+    ~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
+
+({
+    ...get<{foo: number, bar: number, baz: number}>(),
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  [error no-duplicate-spread-property: Property is overridden later.]
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
diff --git a/packages/mimir/test/no-duplicate-spread-property/test.ts b/packages/mimir/test/no-duplicate-spread-property/test.ts
index 44944bb71..d719ed80a 100644
--- a/packages/mimir/test/no-duplicate-spread-property/test.ts
+++ b/packages/mimir/test/no-duplicate-spread-property/test.ts
@@ -2,6 +2,12 @@ export {};
 
 declare function get<T>(): T;
 
+declare class WithMethods {
+    foo(): void;
+    bar: () => void;
+    baz: string;
+}
+
 const foo = 'foo';
 
 ({
@@ -58,3 +64,38 @@ const foo = 'foo';
     let a, b;
     ({[foo]: a, foo: b, ...{}} = get<{foo: string}>());
 }
+
+({
+    foo: 1,
+    bar: 1,
+    baz: 1,
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+    ...get<WithMethods>(),
+});
+
+({
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+    ...get<{foo(): void, bar: () => void, baz: number}>(),
+});
+
+({
+    ...get<WithMethods>(),
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});
+
+({
+    ...get<{foo: number, bar: number, baz: number}>(),
+    foo() {},
+    bar: () => {},
+    baz: get<() => void>(),
+});