feat: various checks for calls (#638)

Closes partially #543

### Summary of Changes

* Warn if results of a call are ignored implicitly in an assignment
* Error if receiver of a call is not callable
* Error if receiver of a call points to a class without a constructor

---------

Co-authored-by: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>

package.json

@@ -72,7 +72,8 @@
         ],
         "configurationDefaults": {
             "[safe-ds]": {
-                "editor.wordSeparators": "`~!@#$%^&*()-=+[]{}\\|;:'\",.<>/?»«"
+                "editor.wordSeparators": "`~!@#$%^&*()-=+[]{}\\|;:'\",.<>/?»«",
+                "files.trimTrailingWhitespace": true
             }
         }
     },

src/language/builtins/safe-ds-annotations.ts

@@ -4,39 +4,41 @@ import { SafeDsModuleMembers } from './safe-ds-module-members.js';
 import { resourceNameToUri } from '../../helpers/resources.js';
 import { URI } from 'langium';
 
-const CORE_ANNOTATIONS_URI = resourceNameToUri('builtins/safeds/lang/coreAnnotations.sdsstub');
+const ANNOTATION_USAGE_URI = resourceNameToUri('builtins/safeds/lang/annotationUsage.sdsstub');
+const IDE_INTEGRATION_URI = resourceNameToUri('builtins/safeds/lang/ideIntegration.sdsstub');
+const MATURITY_URI = resourceNameToUri('builtins/safeds/lang/maturity.sdsstub');
 
 export class SafeDsAnnotations extends SafeDsModuleMembers<SdsAnnotation> {
     isDeprecated(node: SdsAnnotatedObject | undefined): boolean {
         return this.hasAnnotationCallOf(node, this.Deprecated);
     }
 
     private get Deprecated(): SdsAnnotation | undefined {
-        return this.getAnnotation(CORE_ANNOTATIONS_URI, 'Deprecated');
+        return this.getAnnotation(MATURITY_URI, 'Deprecated');
     }
 
     isExperimental(node: SdsAnnotatedObject | undefined): boolean {
         return this.hasAnnotationCallOf(node, this.Experimental);
     }
 
     private get Experimental(): SdsAnnotation | undefined {
-        return this.getAnnotation(CORE_ANNOTATIONS_URI, 'Experimental');
+        return this.getAnnotation(MATURITY_URI, 'Experimental');
     }
 
     isExpert(node: SdsParameter | undefined): boolean {
         return this.hasAnnotationCallOf(node, this.Expert);
     }
 
     private get Expert(): SdsAnnotation | undefined {
-        return this.getAnnotation(CORE_ANNOTATIONS_URI, 'Expert');
+        return this.getAnnotation(IDE_INTEGRATION_URI, 'Expert');
     }
 
     isRepeatable(node: SdsAnnotation | undefined): boolean {
         return this.hasAnnotationCallOf(node, this.Repeatable);
     }
 
     private get Repeatable(): SdsAnnotation | undefined {
-        return this.getAnnotation(CORE_ANNOTATIONS_URI, 'Repeatable');
+        return this.getAnnotation(ANNOTATION_USAGE_URI, 'Repeatable');
     }
 
     private hasAnnotationCallOf(node: SdsAnnotatedObject | undefined, expected: SdsAnnotation | undefined): boolean {

src/language/helpers/safe-ds-node-mapper.ts

@@ -7,6 +7,8 @@ import {
     isSdsBlock,
     isSdsCall,
     isSdsCallable,
+    isSdsClass,
+    isSdsEnumVariant,
     isSdsNamedType,
     isSdsReference,
     isSdsSegment,
@@ -108,8 +110,17 @@ export class SafeDsNodeMapper {
             }
         }
 
-        // If the RHS is a call, the assignee gets the corresponding result
+        // If the RHS instantiates a class or enum variant, the first assignee gets the entire RHS
         const callable = this.callToCallableOrUndefined(expression);
+        if (isSdsClass(callable) || isSdsEnumVariant(callable)) {
+            if (assigneePosition === 0) {
+                return expression;
+            } else {
+                return undefined;
+            }
+        }
+
+        // Otherwise, the assignee gets the result at the same position
         const abstractResults = abstractResultsOrEmpty(callable);
         return abstractResults[assigneePosition];
     }

src/language/typing/model.ts

@@ -1,11 +1,13 @@
 import {
     isSdsNull,
+    SdsAbstractResult,
     SdsCallable,
     SdsClass,
     SdsDeclaration,
     SdsEnum,
     SdsEnumVariant,
     SdsLiteral,
+    SdsParameter,
 } from '../generated/ast.js';
 
 /* c8 ignore start */
@@ -28,8 +30,8 @@ export class CallableType extends Type {
 
     constructor(
         readonly sdsCallable: SdsCallable,
-        readonly inputType: NamedTupleType,
-        readonly outputType: NamedTupleType,
+        readonly inputType: NamedTupleType<SdsParameter>,
+        readonly outputType: NamedTupleType<SdsAbstractResult>,
     ) {
         super();
     }
@@ -99,10 +101,10 @@ export class LiteralType extends Type {
     }
 }
 
-export class NamedTupleType extends Type {
+export class NamedTupleType<T extends SdsDeclaration> extends Type {
     override readonly isNullable = false;
 
-    constructor(readonly entries: NamedTupleEntry[]) {
+    constructor(readonly entries: NamedTupleEntry<T>[]) {
         super();
     }
 
@@ -125,7 +127,7 @@ export class NamedTupleType extends Type {
         return this;
     }
 
-    override copyWithNullability(_isNullable: boolean): NamedTupleType {
+    override copyWithNullability(_isNullable: boolean): NamedTupleType<T> {
         return this;
     }
 
@@ -159,8 +161,9 @@ export class NamedTupleType extends Type {
     }
 }
 
-export class NamedTupleEntry {
+export class NamedTupleEntry<T extends SdsDeclaration> {
     constructor(
+        readonly sdsDeclaration: T | undefined,
         readonly name: string,
         readonly type: Type,
     ) {}
@@ -169,8 +172,8 @@ export class NamedTupleEntry {
         return `${this.name}: ${this.type}`;
     }
 
-    equals(other: NamedTupleEntry): boolean {
-        return this.name === other.name && this.type.equals(other.type);
+    equals(other: NamedTupleEntry<SdsDeclaration>): boolean {
+        return this.sdsDeclaration === other.sdsDeclaration && this.name === other.name && this.type.equals(other.type);
     }
 }
 

src/language/typing/safe-ds-type-computer.ts

@@ -59,6 +59,7 @@ import {
     isSdsTypeProjection,
     isSdsUnionType,
     isSdsYield,
+    SdsAbstractResult,
     SdsAssignee,
     SdsCall,
     SdsCallableType,
@@ -164,7 +165,7 @@ export class SafeDsTypeComputer {
     private computeTypeOfDeclaration(node: SdsDeclaration): Type {
         if (isSdsAnnotation(node)) {
             const parameterEntries = parametersOrEmpty(node).map(
-                (it) => new NamedTupleEntry(it.name, this.computeType(it.type)),
+                (it) => new NamedTupleEntry(it, it.name, this.computeType(it.type)),
             );
 
             return new CallableType(node, new NamedTupleType(parameterEntries), new NamedTupleType([]));
@@ -193,10 +194,10 @@ export class SafeDsTypeComputer {
 
     private computeTypeOfCallableWithManifestTypes(node: SdsFunction | SdsSegment | SdsCallableType): Type {
         const parameterEntries = parametersOrEmpty(node).map(
-            (it) => new NamedTupleEntry(it.name, this.computeType(it.type)),
+            (it) => new NamedTupleEntry(it, it.name, this.computeType(it.type)),
         );
         const resultEntries = resultsOrEmpty(node.resultList).map(
-            (it) => new NamedTupleEntry(it.name, this.computeType(it.type)),
+            (it) => new NamedTupleEntry(it, it.name, this.computeType(it.type)),
         );
 
         return new CallableType(node, new NamedTupleType(parameterEntries), new NamedTupleType(resultEntries));
@@ -278,18 +279,20 @@ export class SafeDsTypeComputer {
             return this.computeTypeOfCall(node);
         } else if (isSdsBlockLambda(node)) {
             const parameterEntries = parametersOrEmpty(node).map(
-                (it) => new NamedTupleEntry(it.name, this.computeType(it)),
+                (it) => new NamedTupleEntry(it, it.name, this.computeType(it)),
             );
             const resultEntries = blockLambdaResultsOrEmpty(node).map(
-                (it) => new NamedTupleEntry(it.name, this.computeType(it)),
+                (it) => new NamedTupleEntry(it, it.name, this.computeType(it)),
             );
 
             return new CallableType(node, new NamedTupleType(parameterEntries), new NamedTupleType(resultEntries));
         } else if (isSdsExpressionLambda(node)) {
             const parameterEntries = parametersOrEmpty(node).map(
-                (it) => new NamedTupleEntry(it.name, this.computeType(it)),
+                (it) => new NamedTupleEntry(it, it.name, this.computeType(it)),
             );
-            const resultEntries = [new NamedTupleEntry('result', this.computeType(node.result))];
+            const resultEntries = [
+                new NamedTupleEntry<SdsAbstractResult>(undefined, 'result', this.computeType(node.result)),
+            ];
 
             return new CallableType(node, new NamedTupleType(parameterEntries), new NamedTupleType(resultEntries));
         } else if (isSdsIndexedAccess(node)) {

src/language/validation/other/statements/assignments.ts

@@ -1,8 +1,10 @@
-import { isSdsPipeline, SdsAssignment, SdsYield } from '../../../generated/ast.js';
+import { isSdsCall, isSdsPipeline, SdsAssignment, SdsYield } from '../../../generated/ast.js';
 import { getContainerOfType, ValidationAcceptor } from 'langium';
 import { SafeDsServices } from '../../../safe-ds-module.js';
-import { assigneesOrEmpty } from '../../../helpers/nodeProperties.js';
+import { abstractResultsOrEmpty, assigneesOrEmpty } from '../../../helpers/nodeProperties.js';
+import { pluralize } from '../../../helpers/stringUtils.js';
 
+export const CODE_ASSIGNMENT_IMPLICITLY_IGNORED_RESULT = 'assignment/implicitly-ignored-result';
 export const CODE_ASSIGMENT_NOTHING_ASSIGNED = 'assignment/nothing-assigned';
 export const CODE_ASSIGMENT_YIELD_FORBIDDEN_IN_PIPELINE = 'assignment/yield-forbidden-in-pipeline';
 
@@ -19,6 +21,34 @@ export const assignmentAssigneeMustGetValue =
         }
     };
 
+export const assignmentShouldNotImplicitlyIgnoreResult = (services: SafeDsServices) => {
+    const nodeMapper = services.helpers.NodeMapper;
+
+    return (node: SdsAssignment, accept: ValidationAcceptor): void => {
+        const expression = node.expression;
+        if (!isSdsCall(expression)) {
+            return;
+        }
+
+        const assignees = assigneesOrEmpty(node);
+        const callable = nodeMapper.callToCallableOrUndefined(expression);
+        const results = abstractResultsOrEmpty(callable);
+
+        if (results.length > assignees.length) {
+            const kind = pluralize(results.length - assignees.length, 'result');
+            const names = results
+                .slice(assignees.length)
+                .map((result) => `'${result.name}'`)
+                .join(', ');
+
+            accept('warning', `The assignment implicitly ignores the ${kind} ${names}.`, {
+                node,
+                code: CODE_ASSIGNMENT_IMPLICITLY_IGNORED_RESULT,
+            });
+        }
+    };
+};
+
 export const yieldMustNotBeUsedInPipeline = (node: SdsYield, accept: ValidationAcceptor): void => {
     const containingPipeline = getContainerOfType(node, isSdsPipeline);
 

src/language/validation/safe-ds-validator.ts

@@ -34,9 +34,14 @@ import {
     unionTypeShouldNotHaveASingularTypeArgument,
 } from './style.js';
 import { templateStringMustHaveExpressionBetweenTwoStringParts } from './other/expressions/templateStrings.js';
-import { assignmentAssigneeMustGetValue, yieldMustNotBeUsedInPipeline } from './other/statements/assignments.js';
+import {
+    assignmentAssigneeMustGetValue,
+    assignmentShouldNotImplicitlyIgnoreResult,
+    yieldMustNotBeUsedInPipeline,
+} from './other/statements/assignments.js';
 import {
     attributeMustHaveTypeHint,
+    callReceiverMustBeCallable,
     namedTypeMustSetAllTypeParameters,
     parameterMustHaveTypeHint,
     resultMustHaveTypeHint,
@@ -99,7 +104,11 @@ export const registerValidationChecks = function (services: SafeDsServices) {
             assigneeAssignedResultShouldNotBeDeprecated(services),
             assigneeAssignedResultShouldNotBeExperimental(services),
         ],
-        SdsAssignment: [assignmentAssigneeMustGetValue(services), assignmentShouldHaveMoreThanWildcardsAsAssignees],
+        SdsAssignment: [
+            assignmentAssigneeMustGetValue(services),
+            assignmentShouldNotImplicitlyIgnoreResult(services),
+            assignmentShouldHaveMoreThanWildcardsAsAssignees,
+        ],
         SdsAnnotation: [
             annotationMustContainUniqueNames,
             annotationParameterListShouldNotBeEmpty,
@@ -118,7 +127,7 @@ export const registerValidationChecks = function (services: SafeDsServices) {
         SdsArgumentList: [argumentListMustNotHavePositionalArgumentsAfterNamedArguments],
         SdsAttribute: [attributeMustHaveTypeHint],
         SdsBlockLambda: [blockLambdaMustContainUniqueNames],
-        SdsCall: [callArgumentListShouldBeNeeded(services)],
+        SdsCall: [callArgumentListShouldBeNeeded(services), callReceiverMustBeCallable(services)],
         SdsCallableType: [
             callableTypeMustContainUniqueNames,
             callableTypeMustNotHaveOptionalParameters,

src/language/validation/types.ts

@@ -1,13 +1,65 @@
 import { getContainerOfType, ValidationAcceptor } from 'langium';
-import { isSdsCallable, isSdsLambda, SdsAttribute, SdsNamedType, SdsParameter, SdsResult } from '../generated/ast.js';
+import {
+    isSdsAnnotation,
+    isSdsCallable,
+    isSdsClass,
+    isSdsLambda,
+    isSdsMemberAccess,
+    isSdsPipeline,
+    isSdsReference,
+    isSdsSchema,
+    SdsAttribute,
+    SdsCall,
+    SdsNamedType,
+    SdsParameter,
+    SdsResult,
+} from '../generated/ast.js';
 import { typeArgumentsOrEmpty, typeParametersOrEmpty } from '../helpers/nodeProperties.js';
 import { isEmpty } from 'radash';
 import { SafeDsServices } from '../safe-ds-module.js';
 import { pluralize } from '../helpers/stringUtils.js';
 
+export const CODE_TYPE_CALLABLE_RECEIVER = 'type/callable-receiver';
 export const CODE_TYPE_MISSING_TYPE_ARGUMENTS = 'type/missing-type-arguments';
 export const CODE_TYPE_MISSING_TYPE_HINT = 'type/missing-type-hint';
 
+// -----------------------------------------------------------------------------
+// Type checking
+// -----------------------------------------------------------------------------
+
+export const callReceiverMustBeCallable = (services: SafeDsServices) => {
+    const nodeMapper = services.helpers.NodeMapper;
+
+    return (node: SdsCall, accept: ValidationAcceptor): void => {
+        let receiver = node.receiver;
+        if (isSdsMemberAccess(receiver)) {
+            receiver = receiver.member;
+        }
+
+        if (isSdsReference(receiver)) {
+            const target = receiver.target.ref;
+
+            // We already report other errors at this position in those cases
+            if (!target || isSdsAnnotation(target) || isSdsPipeline(target) || isSdsSchema(target)) {
+                return;
+            }
+        }
+
+        const callable = nodeMapper.callToCallableOrUndefined(node);
+        if (!callable) {
+            accept('error', 'This expression is not callable.', {
+                node: node.receiver,
+                code: CODE_TYPE_CALLABLE_RECEIVER,
+            });
+        } else if (isSdsClass(callable) && !callable.parameterList) {
+            accept('error', 'Cannot instantiate a class that has no constructor.', {
+                node: node.receiver,
+                code: CODE_TYPE_CALLABLE_RECEIVER,
+            });
+        }
+    };
+};
+
 // -----------------------------------------------------------------------------
 // Missing type arguments
 // -----------------------------------------------------------------------------