feat: port additional validation checks to `Langium (#576)

Closes partially #543

### Summary of Changes

Show an error if:
* A union type has no type arguments
* A callable type has optional parameters
* Positional type arguments occur after named type arguments
* Positional arguments occur after named arguments
* A parameter is variadic and optional

---------

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

src/language/grammar/safe-ds.langium

@@ -1045,16 +1045,16 @@ terminal TEMPLATE_STRING_END returns string: TEMPLATE_EXPRESSION_END STRING_TEXT
 terminal CALL_TYPE_ARGUMENT_LIST_START:
     '<'
     (?=
-        /\s*/
-        (   '*'                                 // Star projection as positional type argument
-        |   'in'                                // Contravariant type projection as positional type argument
-        |   'out'                               // Covariant type projection as positional type argument
-        |   'literal'                           // Invariant literal type as positional type argument
-        |   'union'                             // Invariant union type as positional type argument
-        |   '>'                                 // Empty type argument list
-        |    ID /\s*/
-            ( '='                               // Named type argument
-            | ('.' /\s*/ ID /\s*/)* (',' | '>') // Invariant type projection as positional type argument
+        /[\s»«]*/
+        (   '*'                                         // Star projection as positional type argument
+        |   'in'                                        // Contravariant type projection as positional type argument
+        |   'out'                                       // Covariant type projection as positional type argument
+        |   'literal'                                   // Invariant literal type as positional type argument
+        |   'union'                                     // Invariant union type as positional type argument
+        |   '>'                                         // Empty type argument list
+        |    ID /[\s»«]*/
+            ( '='                                       // Named type argument
+            | ('.' /[\s»«]*/ ID /[\s»«]*/)* (',' | '>') // Invariant type projection as positional type argument
             )
         )
     )

src/language/validation/other/argumentLists.ts

@@ -0,0 +1,21 @@
+import { SdsArgumentList } from '../../generated/ast.js';
+import { ValidationAcceptor } from 'langium';
+
+export const CODE_ARGUMENT_LIST_POSITIONAL_AFTER_NAMED = 'argument-list/positional-after-named';
+
+export const argumentListMustNotHavePositionalArgumentsAfterNamedArguments = (
+    node: SdsArgumentList,
+    accept: ValidationAcceptor,
+): void => {
+    let foundNamed = false;
+    for (const argument of node.arguments) {
+        if (argument.parameter) {
+            foundNamed = true;
+        } else if (foundNamed) {
+            accept('error', 'After the first named argument all arguments must be named.', {
+                node: argument,
+                code: CODE_ARGUMENT_LIST_POSITIONAL_AFTER_NAMED,
+            });
+        }
+    }
+};

src/language/validation/other/declarations/parameterLists.ts

@@ -11,9 +11,9 @@ export const parameterListMustNotHaveOptionalAndVariadicParameters = (
 ) => {
     const hasOptional = node.parameters.find((p) => p.defaultValue);
     if (hasOptional) {
-        const variadicParameters = node.parameters.filter((p) => p.variadic);
+        const variadicRequiredParameters = node.parameters.filter((p) => p.variadic && !p.defaultValue);
 
-        for (const variadic of variadicParameters) {
+        for (const variadic of variadicRequiredParameters) {
             accept('error', 'A callable with optional parameters must not have a variadic parameter.', {
                 node: variadic,
                 property: 'name',

src/language/validation/other/declarations/parameters.ts

@@ -0,0 +1,14 @@
+import { SdsParameter } from '../../../generated/ast.js';
+import { ValidationAcceptor } from 'langium';
+
+export const CODE_PARAMETER_VARIADIC_AND_OPTIONAL = 'parameter/variadic-and-optional';
+
+export const parameterMustNotBeVariadicAndOptional = (node: SdsParameter, accept: ValidationAcceptor) => {
+    if (node.variadic && node.defaultValue) {
+        accept('error', 'Variadic parameters must not be optional.', {
+            node,
+            property: 'name',
+            code: CODE_PARAMETER_VARIADIC_AND_OPTIONAL,
+        });
+    }
+};

src/language/validation/imports.ts → src/language/validation/other/imports.ts

@@ -1,6 +1,6 @@
 import { ValidationAcceptor } from 'langium';
-import { SdsImportAlias } from '../generated/ast.js';
-import { isWildcardImport } from '../ast/checks.js';
+import { SdsImportAlias } from '../../generated/ast.js';
+import { isWildcardImport } from '../../ast/checks.js';
 
 export const CODE_IMPORT_WILDCARD_IMPORT_WITH_ALIAS = 'import/wildcard-import-with-alias';
 

src/language/validation/other/types/callableTypes.ts

@@ -0,0 +1,17 @@
+import { SdsCallableType } from '../../../generated/ast.js';
+import { ValidationAcceptor } from 'langium';
+import { parametersOrEmpty } from '../../../ast/shortcuts.js';
+
+export const CODE_CALLABLE_TYPE_NO_OPTIONAL_PARAMETERS = 'callable-type/no-optional-parameters';
+
+export const callableTypeMustNotHaveOptionalParameters = (node: SdsCallableType, accept: ValidationAcceptor): void => {
+    for (const parameter of parametersOrEmpty(node.parameterList)) {
+        if (parameter.defaultValue && !parameter.variadic) {
+            accept('error', 'A callable type must not have optional parameters.', {
+                node: parameter,
+                property: 'defaultValue',
+                code: CODE_CALLABLE_TYPE_NO_OPTIONAL_PARAMETERS,
+            });
+        }
+    }
+};

src/language/validation/other/types/typeArgumentLists.ts

@@ -0,0 +1,21 @@
+import { SdsTypeArgumentList } from '../../../generated/ast.js';
+import { ValidationAcceptor } from 'langium';
+
+export const CODE_TYPE_ARGUMENT_LIST_POSITIONAL_AFTER_NAMED = 'type-argument-list/positional-after-named';
+
+export const typeArgumentListMustNotHavePositionalArgumentsAfterNamedArguments = (
+    node: SdsTypeArgumentList,
+    accept: ValidationAcceptor,
+): void => {
+    let foundNamed = false;
+    for (const typeArgument of node.typeArguments) {
+        if (typeArgument.typeParameter) {
+            foundNamed = true;
+        } else if (foundNamed) {
+            accept('error', 'After the first named type argument all type arguments must be named.', {
+                node: typeArgument,
+                code: CODE_TYPE_ARGUMENT_LIST_POSITIONAL_AFTER_NAMED,
+            });
+        }
+    }
+};

src/language/validation/other/types/unionTypes.ts

@@ -0,0 +1,16 @@
+import { SdsUnionType } from '../../../generated/ast.js';
+import { ValidationAcceptor } from 'langium';
+import { typeArgumentsOrEmpty } from '../../../ast/shortcuts.js';
+import { isEmpty } from 'radash';
+
+export const CODE_UNION_TYPE_MISSING_TYPE_ARGUMENTS = 'union-type/missing-type-arguments';
+
+export const unionTypeMustHaveTypeArguments = (node: SdsUnionType, accept: ValidationAcceptor): void => {
+    if (isEmpty(typeArgumentsOrEmpty(node.typeArgumentList))) {
+        accept('error', 'A union type must have least one type argument.', {
+            node,
+            property: 'typeArgumentList',
+            code: CODE_UNION_TYPE_MISSING_TYPE_ARGUMENTS,
+        });
+    }
+};

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

@@ -37,7 +37,12 @@ import {
     parameterListMustNotHaveRequiredParametersAfterOptionalParameters,
     parameterListVariadicParameterMustBeLast,
 } from './other/declarations/parameterLists.js';
-import { importAliasMustNotBeUsedForWildcardImports } from './imports.js';
+import { importAliasMustNotBeUsedForWildcardImports } from './other/imports.js';
+import { unionTypeMustHaveTypeArguments } from './other/types/unionTypes.js';
+import { callableTypeMustNotHaveOptionalParameters } from './other/types/callableTypes.js';
+import { typeArgumentListMustNotHavePositionalArgumentsAfterNamedArguments } from './other/types/typeArgumentLists.js';
+import { argumentListMustNotHavePositionalArgumentsAfterNamedArguments } from './other/argumentLists.js';
+import { parameterMustNotBeVariadicAndOptional } from './other/declarations/parameters.js';
 
 /**
  * Register custom validation checks.
@@ -48,9 +53,10 @@ export const registerValidationChecks = function (services: SafeDsServices) {
     const checks: ValidationChecks<SafeDsAstType> = {
         SdsAssignment: [assignmentShouldHaveMoreThanWildcardsAsAssignees],
         SdsAnnotation: [annotationMustContainUniqueNames, annotationParameterListShouldNotBeEmpty],
+        SdsArgumentList: [argumentListMustNotHavePositionalArgumentsAfterNamedArguments],
         SdsAttribute: [attributeMustHaveTypeHint],
         SdsBlockLambda: [blockLambdaMustContainUniqueNames],
-        SdsCallableType: [callableTypeMustContainUniqueNames],
+        SdsCallableType: [callableTypeMustContainUniqueNames, callableTypeMustNotHaveOptionalParameters],
         SdsClass: [classMustContainUniqueNames],
         SdsClassBody: [classBodyShouldNotBeEmpty],
         SdsConstraintList: [constraintListShouldNotBeEmpty],
@@ -62,7 +68,7 @@ export const registerValidationChecks = function (services: SafeDsServices) {
         SdsFunction: [functionMustContainUniqueNames, functionResultListShouldNotBeEmpty],
         SdsImportAlias: [importAliasMustNotBeUsedForWildcardImports],
         SdsModule: [moduleDeclarationsMustMatchFileKind, moduleWithDeclarationsMustStatePackage],
-        SdsParameter: [parameterMustHaveTypeHint],
+        SdsParameter: [parameterMustHaveTypeHint, parameterMustNotBeVariadicAndOptional],
         SdsParameterList: [
             parameterListMustNotHaveOptionalAndVariadicParameters,
             parameterListMustNotHaveRequiredParametersAfterOptionalParameters,
@@ -72,9 +78,10 @@ export const registerValidationChecks = function (services: SafeDsServices) {
         SdsResult: [resultMustHaveTypeHint],
         SdsSegment: [segmentMustContainUniqueNames, segmentResultListShouldNotBeEmpty],
         SdsTemplateString: [templateStringMustHaveExpressionBetweenTwoStringParts],
+        SdsTypeArgumentList: [typeArgumentListMustNotHavePositionalArgumentsAfterNamedArguments],
         SdsTypeParameterConstraint: [typeParameterConstraintLeftOperandMustBeOwnTypeParameter],
         SdsTypeParameterList: [typeParameterListShouldNotBeEmpty],
-        SdsUnionType: [unionTypeShouldNotHaveASingularTypeArgument],
+        SdsUnionType: [unionTypeMustHaveTypeArguments, unionTypeShouldNotHaveASingularTypeArgument],
         SdsYield: [yieldMustNotBeUsedInPipeline],
     };
     registry.register(checks, validator);

src/language/validation/value.ts

@@ -0,0 +1,3 @@
+// TODO: implement value-related checks here, including:
+//  - division by zero
+//  - must be constant

tests/language/validation/testValidation.test.ts

@@ -1,4 +1,4 @@
-import { afterEach, describe, it } from 'vitest';
+import { afterEach, beforeEach, describe, it } from 'vitest';
 import { createSafeDsServices } from '../../../src/language/safe-ds-module.js';
 import { URI } from 'vscode-uri';
 import { NodeFileSystem } from 'langium/node';
@@ -11,6 +11,11 @@ import { locationToString } from '../../helpers/location.js';
 const services = createSafeDsServices(NodeFileSystem).SafeDs;
 
 describe('validation', async () => {
+    beforeEach(async () => {
+        // Load the builtin library
+        await services.shared.workspace.WorkspaceManager.initializeWorkspace([]);
+    });
+
     afterEach(async () => {
         await clearDocuments(services);
     });

tests/resources/grammar/expressions/calls/good-named type argument with test markers.sdstest

@@ -0,0 +1,5 @@
+// $TEST$ no_syntax_error
+
+pipeline myPipeline {
+    f<»T = Int«>();
+}

tests/resources/grammar/expressions/calls/good-positional type argument with tests markers.sdstest

@@ -0,0 +1,5 @@
+// $TEST$ no_syntax_error
+
+pipeline myPipeline {
+    f<»Int«>();
+}

tests/resources/validation/other/argument lists/must not have positional argument after named argument/main.sdstest

@@ -0,0 +1,63 @@
+package tests.validation.other.argumentLists.mustNotHavePositionalArgumentAfterNamedArgument
+
+annotation MyAnnotation(a: Int, b: Int = 0, c: Int = 0, d: Int = 0, vararg e: Int)
+
+// $TEST$ no error "After the first named argument all arguments must be named."
+// $TEST$ no error "After the first named argument all arguments must be named."
+// $TEST$ error "After the first named argument all arguments must be named."
+// $TEST$ no error "After the first named argument all arguments must be named."
+// $TEST$ error "After the first named argument all arguments must be named."
+@MyAnnotation(»0«, »a = 1«, »2«, »b = 3«, »4«)
+class MyClass1
+
+// $TEST$ no error "After the first named argument all arguments must be named."
+@MyAnnotation(»0«)
+class MyClass2
+
+// $TEST$ no error "After the first named argument all arguments must be named."
+@MyAnnotation(»a = 0«)
+class MyClass3
+
+// $TEST$ no error "After the first named argument all arguments must be named."
+// $TEST$ no error "After the first named argument all arguments must be named."
+// $TEST$ error "After the first named argument all arguments must be named."
+// $TEST$ no error "After the first named argument all arguments must be named."
+@UnresolvedAnnotation(»0«, »a = 1«, »2«, »b = 3«)
+class MyClass4
+
+// $TEST$ no error "After the first named argument all arguments must be named."
+@UnresolvedAnnotation(»0«)
+class MyClass5
+
+// $TEST$ no error "After the first named argument all arguments must be named."
+@UnresolvedAnnotation(»a = 0«)
+class MyClass3
+
+fun f(a: Int, b: Int = 0, c: Int = 0, d: Int = 0, vararg e: Int)
+
+pipeline myPipeline {
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    // $TEST$ error "After the first named argument all arguments must be named."
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    // $TEST$ error "After the first named argument all arguments must be named."
+    f(»0«, »a = 1«, »2«, »b = 3«, »4«);
+
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    f(»0«);
+
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    f(»a = 0«);
+
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    // $TEST$ error "After the first named argument all arguments must be named."
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    unresolvedCallable(»0«, »a = 1«, »2«, »b = 3«);
+
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    unresolvedCallable(»0«);
+
+    // $TEST$ no error "After the first named argument all arguments must be named."
+    unresolvedCallable(»a = 0«);
+}

tests/resources/validation/other/declarations/parameter lists/must not mix optional and variadic/main.sdstest

@@ -9,7 +9,7 @@ annotation MyAnnotation1(»a«: Int, »b«: Int = 1, »c«: Int, »d«: Int = 2,
 
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-annotation MyAnnotation2(»a«: Int, vararg »b«: Int)
+annotation MyAnnotation2(»a«: Int, vararg »b«: Int = 1)
 
 // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
@@ -26,7 +26,7 @@ class MyClass1(»a«: Int, »b«: Int = 1, »c«: Int, »d«: Int = 2, vararg »
 
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-class MyClass2(»a«: Int, vararg »b«: Int)
+class MyClass2(»a«: Int, vararg »b«: Int = 1)
 
 // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
@@ -44,7 +44,7 @@ enum MyEnum {
 
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-    MyEnumVariant2(»a«: Int, vararg »b«: Int)
+    MyEnumVariant2(»a«: Int, vararg »b«: Int = 1)
 
     // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
@@ -62,7 +62,7 @@ fun myFunction1(»a«: Int, »b«: Int = 1, »c«: Int, »d«: Int = 2, vararg 
 
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-fun myFunction2(»a«: Int, vararg »b«: Int)
+fun myFunction2(»a«: Int, vararg »b«: Int = 1)
 
 // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
@@ -79,7 +79,7 @@ segment mySegment1(»a«: Int, »b«: Int = 1, »c«: Int, »d«: Int = 2, varar
 
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-segment mySegment2(»a«: Int, vararg »b«: Int) {}
+segment mySegment2(»a«: Int, vararg »b«: Int = 1) {}
 
 // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
 // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
@@ -97,7 +97,7 @@ pipeline myPipeline {
 
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-    (»a«: Int, vararg »b«: Int) {};
+    (»a«: Int, vararg »b«: Int = 1) {};
 
     // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
@@ -114,7 +114,7 @@ pipeline myPipeline {
 
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-    (»a«: Int, vararg »b«: Int) -> 1;
+    (»a«: Int, vararg »b«: Int = 1) -> 1;
 
     // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
@@ -133,7 +133,7 @@ fun myFunction4(
 
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."
-    p2: (»a«: Int, vararg »b«: Int) -> (),
+    p2: (»a«: Int, vararg »b«: Int = 1) -> (),
 
     // $TEST$ error "A callable with optional parameters must not have a variadic parameter."
     // $TEST$ no error "A callable with optional parameters must not have a variadic parameter."

tests/resources/validation/other/declarations/parameter/variadic must not be optional/main.sdstest

@@ -0,0 +1,12 @@
+package tests.validation.declarations.parameters.variadicMustNotBeOptional
+
+fun f(
+    // $TEST$ no error "Variadic parameters must not be optional."
+    »a«: Int,
+    // $TEST$ no error "Variadic parameters must not be optional."
+    »b«: Int = 1,
+    // $TEST$ no error "Variadic parameters must not be optional."
+    vararg »c«: Int,
+    // $TEST$ error "Variadic parameters must not be optional."
+    vararg »d«: Int = 2
+)

tests/resources/validation/other/types/callable types/must not have optional parameters/optional.sdstest

@@ -0,0 +1,8 @@
+package tests.validation.types.callableTypes.mustNotHaveOptionalParameters
+
+fun f(
+    g: (
+        // $TEST$ error "A callable type must not have optional parameters."
+        p: Int = »1«,
+    ) -> ()
+)

tests/resources/validation/other/types/callable types/must not have optional parameters/required.sdstest

@@ -0,0 +1,8 @@
+package tests.validation.types.callableTypes.mustNotHaveOptionalParameters
+
+fun f(
+    g: (
+        // $TEST$ no error "A callable type must not have optional parameters."
+        p: Int,
+    ) -> ()
+)

tests/resources/validation/other/types/callable types/must not have optional parameters/variadic optional.sdstest

@@ -0,0 +1,8 @@
+package tests.validation.types.callableTypes.mustNotHaveOptionalParameters
+
+fun f(
+    g: (
+        // $TEST$ no error "A callable type must not have optional parameters."
+        vararg p: Int = 1,
+    ) -> ()
+)