Added a check for class pattern matches where the number of positional patterns exceeds the number of positional fields supported by the class. This addresses #6019.

packages/pyright-internal/src/analyzer/patternMatching.ts

@@ -1669,16 +1669,9 @@ export function validateClassPattern(evaluator: TypeEvaluator, pattern: PatternC
     } else {
         const isBuiltIn = isClassSpecialCaseForClassPattern(exprType);
 
-        // If it's a special-case builtin class, only one positional argument is allowed.
+        // If it's a special-case builtin class, only positional arguments are allowed.
         if (isBuiltIn) {
-            if (pattern.arguments.length > 1) {
-                evaluator.addDiagnostic(
-                    getFileInfo(pattern).diagnosticRuleSet.reportGeneralTypeIssues,
-                    DiagnosticRule.reportGeneralTypeIssues,
-                    Localizer.Diagnostic.classPatternBuiltInArgCount(),
-                    pattern.arguments[1]
-                );
-            } else if (pattern.arguments.length === 1 && pattern.arguments[0].name) {
+            if (pattern.arguments.length === 1 && pattern.arguments[0].name) {
                 evaluator.addDiagnostic(
                     getFileInfo(pattern).diagnosticRuleSet.reportGeneralTypeIssues,
                     DiagnosticRule.reportGeneralTypeIssues,
@@ -1687,6 +1680,36 @@ export function validateClassPattern(evaluator: TypeEvaluator, pattern: PatternC
                 );
             }
         }
+
+        // Emits an error if the supplied number of positional patterns is less than
+        // expected for the given subject type.
+        let positionalPatternCount = pattern.arguments.findIndex((arg) => arg.name !== undefined);
+        if (positionalPatternCount < 0) {
+            positionalPatternCount = pattern.arguments.length;
+        }
+
+        let expectedPatternCount = 1;
+        if (!isBuiltIn) {
+            let positionalArgNames: string[] = [];
+            if (pattern.arguments.some((arg) => !arg.name)) {
+                positionalArgNames = getPositionalMatchArgNames(evaluator, exprType);
+            }
+
+            expectedPatternCount = positionalArgNames.length;
+        }
+
+        if (positionalPatternCount > expectedPatternCount) {
+            evaluator.addDiagnostic(
+                getFileInfo(pattern).diagnosticRuleSet.reportGeneralTypeIssues,
+                DiagnosticRule.reportGeneralTypeIssues,
+                Localizer.Diagnostic.classPatternPositionalArgCount().format({
+                    type: exprType.details.name,
+                    expected: expectedPatternCount,
+                    received: positionalPatternCount,
+                }),
+                pattern.arguments[expectedPatternCount]
+            );
+        }
     }
 }
 

packages/pyright-internal/src/localization/localize.ts

@@ -281,9 +281,12 @@ export namespace Localizer {
         export const classMethodClsParam = () => getRawString('Diagnostic.classMethodClsParam');
         export const classNotRuntimeSubscriptable = () =>
             new ParameterizedString<{ name: string }>(getRawString('Diagnostic.classNotRuntimeSubscriptable'));
-        export const classPatternBuiltInArgCount = () => getRawString('Diagnostic.classPatternBuiltInArgCount');
         export const classPatternBuiltInArgPositional = () =>
             getRawString('Diagnostic.classPatternBuiltInArgPositional');
+        export const classPatternPositionalArgCount = () =>
+            new ParameterizedString<{ type: string; expected: number; received: number }>(
+                getRawString('Diagnostic.classPatternPositionalArgCount')
+            );
         export const classPatternTypeAlias = () =>
             new ParameterizedString<{ type: string }>(getRawString('Diagnostic.classPatternTypeAlias'));
         export const classTypeParametersIllegal = () => getRawString('Diagnostic.classTypeParametersIllegal');

packages/pyright-internal/src/localization/package.nls.cs.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "Přepsání __class_getitem__ by mělo mít parametr cls",
         "classMethodClsParam": "Metody třídy by měly mít parametr „cls“",
         "classNotRuntimeSubscriptable": "Dolní index pro třídu {name} vygeneruje výjimku modulu runtime; anotaci typu uzavřete do uvozovek",
-        "classPatternBuiltInArgCount": "Vzor třídy přijímá maximálně 1 poziční dílčí vzor",
         "classPatternBuiltInArgPositional": "Vzor třídy přijímá pouze poziční dílčí vzor",
         "classPatternTypeAlias": "Typ „{type}“ nelze použít ve vzorci třídy, protože se jedná o specializovaný alias typu",
         "classTypeParametersIllegal": "Syntaxe parametru typu třídy vyžaduje Python 312 nebo novější",

packages/pyright-internal/src/localization/package.nls.de.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ Außerkraftsetzung sollte einen \"cls\"-Parameter annehmen.",
         "classMethodClsParam": "Klassenmethoden sollten einen \"cls\"-Parameter verwenden.",
         "classNotRuntimeSubscriptable": "Durch das Tiefstellungsskript für die Klasse \"{name}\" wird eine Laufzeitausnahme generiert; schließen Sie die Typanmerkung in Anführungszeichen ein",
-        "classPatternBuiltInArgCount": "Das Klassenmuster akzeptiert höchstens 1 positionsbezogenes Untermuster.",
         "classPatternBuiltInArgPositional": "Das Klassenmuster akzeptiert nur positionsbezogenes Untermuster.",
         "classPatternTypeAlias": "\"{type}\" kann nicht in einem Klassenmuster verwendet werden, da es sich um einen spezialisierten Typalias handelt.",
         "classTypeParametersIllegal": "Die Syntax des Klassentypparameters erfordert Python 3.12 oder höher.",

packages/pyright-internal/src/localization/package.nls.en-us.json

@@ -52,8 +52,8 @@
         "classGetItemClsParam": "__class_getitem__ override should take a \"cls\" parameter",
         "classMethodClsParam": "Class methods should take a \"cls\" parameter",
         "classNotRuntimeSubscriptable": "Subscript for class \"{name}\" will generate runtime exception; enclose type annotation in quotes",
-        "classPatternBuiltInArgCount": "Class pattern accepts at most 1 positional sub-pattern",
         "classPatternBuiltInArgPositional": "Class pattern accepts only positional sub-pattern",
+        "classPatternPositionalArgCount": "Too many positional patterns for class \"{type}\"; expected {expected} but received {received}",
         "classPatternTypeAlias": "\"{type}\" cannot be used in a class pattern because it is a specialized type alias",
         "classTypeParametersIllegal": "Class type parameter syntax requires Python 3.12 or newer",
         "classVarNotAllowed": "\"ClassVar\" is not allowed in this context",

packages/pyright-internal/src/localization/package.nls.es.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ debe tomar un parámetro \"cls\"",
         "classMethodClsParam": "Los métodos de clase deben tomar un parámetro \"cls\"",
         "classNotRuntimeSubscriptable": "El subíndice para la clase \"{name}\" generará una excepción en tiempo de ejecución; encierre la anotación de tipo entre comillas",
-        "classPatternBuiltInArgCount": "El patrón de clase acepta como máximo 1 subpatrón posicional",
         "classPatternBuiltInArgPositional": "El patrón de clase solo acepta subpatrones posicionales",
         "classPatternTypeAlias": "\"{type}\" no se puede usar en un patrón de clase porque es un alias de tipo especializado",
         "classTypeParametersIllegal": "La sintaxis de los parámetros de tipo de clase requiere Python 3.12 o posterior.",

packages/pyright-internal/src/localization/package.nls.fr.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ remplacement doit prendre un paramètre « cls »",
         "classMethodClsParam": "Les méthodes de classe doivent prendre un paramètre \"cls\"",
         "classNotRuntimeSubscriptable": "L’indice de la classe « {name} » génère une exception d’exécution ; placer l’annotation de type entre guillemets",
-        "classPatternBuiltInArgCount": "Le modèle de classe accepte au maximum 1 sous-modèle positionnel",
         "classPatternBuiltInArgPositional": "Le modèle de classe accepte uniquement le sous-modèle positionnel",
         "classPatternTypeAlias": "\"{type}\" ne peut pas être utilisé dans un modèle de classe car il s'agit d'un alias de type spécialisé",
         "classTypeParametersIllegal": "La syntaxe du paramètre de type de classe nécessite Python 3.12 ou version ultérieure",

packages/pyright-internal/src/localization/package.nls.it.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ override deve accettare un parametro \"cls\"",
         "classMethodClsParam": "I metodi di classe devono accettare un parametro \"cls\"",
         "classNotRuntimeSubscriptable": "Il pedice per la classe \"{name}\" genererà un'eccezione di runtime; racchiudere l'annotazione di tipo tra virgolette",
-        "classPatternBuiltInArgCount": "Il modello di classe accetta al massimo 1 sotto pattern posizionale",
         "classPatternBuiltInArgPositional": "Il modello di classe accetta solo un sotto pattern posizionale",
         "classPatternTypeAlias": "\"{type}\" non può essere usato in uno schema di classe, perché è un alias di tipo specializzato",
         "classTypeParametersIllegal": "La sintassi del parametro del tipo di classe richiede Python 3.12 o versione successiva",

packages/pyright-internal/src/localization/package.nls.ja.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ override は \"cls\" パラメーターを受け取る必要があります",
         "classMethodClsParam": "クラス メソッドは \"cls\" パラメーターを受け取る必要があります",
         "classNotRuntimeSubscriptable": "クラス \"{name}\" の添字はランタイム例外を生成します。型の注釈を引用符で囲む",
-        "classPatternBuiltInArgCount": "クラス パターンは、最大 1 つの位置指定サブパターンを受け入れます",
         "classPatternBuiltInArgPositional": "クラス パターンは位置指定サブパターンのみを受け入れます",
         "classPatternTypeAlias": "\"{type}\" は特殊な型エイリアスであるため、クラス パターンでは使用できません",
         "classTypeParametersIllegal": "クラス型パラメーターの構文には Python 3.12 以降が必要です",

packages/pyright-internal/src/localization/package.nls.ko.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ 재정의는 \"cls\" 매개 변수를 사용해야 합니다.",
         "classMethodClsParam": "클래스 메서드는 ‘cls’ 매개 변수를 사용해야 합니다.",
         "classNotRuntimeSubscriptable": "클래스 \"{name}\"에 대한 첨자는 런타임 예외를 생성합니다. 따옴표로 형식 주석 묶기",
-        "classPatternBuiltInArgCount": "클래스 패턴은 최대 1개의 위치 하위 패턴을 허용합니다.",
         "classPatternBuiltInArgPositional": "클래스 패턴은 위치 하위 패턴만 허용합니다.",
         "classPatternTypeAlias": "‘{type}’은(는) 특수 형식 별칭이므로 클래스 패턴에서 사용할 수 없습니다.",
         "classTypeParametersIllegal": "클래스 형식 매개 변수 구문에는 Python 3.12 이상이 필요합니다.",

packages/pyright-internal/src/localization/package.nls.pl.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "Przesłonięcie __class_getitem__ powinno przyjmować parametr „cls”.",
         "classMethodClsParam": "Metody klasy powinny przyjmować parametr „cls”",
         "classNotRuntimeSubscriptable": "Indeks dolny dla klasy „{name}” wygeneruje wyjątek czasu uruchamiania; umieść adnotację typu w cudzysłowie",
-        "classPatternBuiltInArgCount": "Wzorzec klasy akceptuje co najwyżej 1 podwzorzec pozycyjny",
         "classPatternBuiltInArgPositional": "Wzorzec klasy akceptuje tylko podwzorzec pozycyjny",
         "classPatternTypeAlias": "„{type}” nie może być używany we wzorcu klasy, ponieważ jest to alias typu specjalnego",
         "classTypeParametersIllegal": "Składnia parametru typu klasy wymaga języka Python w wersji 3.12 lub nowszej",

packages/pyright-internal/src/localization/package.nls.pt-br.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "A substituição__class_getitem__ deve usar um parâmetro \"cls\"",
         "classMethodClsParam": "Os métodos de classe devem usar um parâmetro \"cls\"",
         "classNotRuntimeSubscriptable": "O subscrito para a classe \"{name}\" gerará uma exceção de runtime. Coloque a anotação de tipo entre aspas",
-        "classPatternBuiltInArgCount": "O padrão de classe aceita no máximo 1 sub-padrão posicional",
         "classPatternBuiltInArgPositional": "O padrão de classe aceita apenas sub-padrão posicional",
         "classPatternTypeAlias": "\"{type}\" não pode ser usado em um padrão de classe porque é um alias de tipo especializado",
         "classTypeParametersIllegal": "A sintaxe do parâmetro de tipo de classe requer o Python 3.12 ou mais recente",

packages/pyright-internal/src/localization/package.nls.qps-ploc.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "[A2iHF][นั้__çlæss_gëtïtëm__ øvërrïðë shøµlð tækë æ \"çls\" pæræmëtërẤğ倪İЂҰक्र्तिृまẤğ倪İЂҰक्นั้ढूँ]",
         "classMethodClsParam": "[aWMN3][นั้Çlæss mëthøðs shøµlð tækë æ \"çls\" pæræmëtërẤğ倪İЂҰक्र्तिृまẤğ倪นั้ढूँ]",
         "classNotRuntimeSubscriptable": "[O9BL6][นั้§µþsçrïpt før çlæss \"{ñæmë}\" wïll gëñërætë rµñtïmë ëxçëptïøñ; ëñçløsë tÿpë æññøtætïøñ ïñ qµøtësẤğ倪İЂҰक्र्तिृまẤğ倪İЂҰक्र्तिृまẤğ倪İЂҰक्र्นั้ढूँ]",
-        "classPatternBuiltInArgCount": "[moI4V][นั้Çlæss pættërñ æççëpts æt møst 1 pøsïtïøñæl sµþ-pættërñẤğ倪İЂҰक्र्तिृまẤğ倪İЂҰक्นั้ढूँ]",
         "classPatternBuiltInArgPositional": "[DOfs5][นั้Çlæss pættërñ æççëpts øñlÿ pøsïtïøñæl sµþ-pættërñẤğ倪İЂҰक्र्तिृまẤğ倪İЂҰนั้ढूँ]",
         "classPatternTypeAlias": "[AxDtv][นั้\"{tÿpë}\" çæññøt þë µsëð ïñ æ çlæss pættërñ þëçæµsë ït ïs æ spëçïælïzëð tÿpë ælïæsẤğ倪İЂҰक्र्तिृまẤğ倪İЂҰक्र्तिृまẤğ倪İนั้ढूँ]",
         "classTypeParametersIllegal": "[GybXD][นั้Çlæss tÿpë pæræmëtër sÿñtæx rëqµïrës Pÿthøñ 3.12 ør ñëwërẤğ倪İЂҰक्र्तिृまẤğ倪İЂҰक्र्นั้ढूँ]",

packages/pyright-internal/src/localization/package.nls.ru.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "Переопределение метода __class_getitem__ должно принимать параметр \"cls\"",
         "classMethodClsParam": "Методы класса должны принимать параметр cls",
         "classNotRuntimeSubscriptable": "Операция взятия подстроки для класса \"{name}\" создаст исключение среды выполнения; заключите заметку типа в кавычки",
-        "classPatternBuiltInArgCount": "Шаблон класса принимает не более одного позиционного вложенного шаблона",
         "classPatternBuiltInArgPositional": "Шаблон класса принимает только позиционный вложенный шаблон",
         "classPatternTypeAlias": "\"{type}\" нельзя использовать в шаблоне класса, поскольку это псевдоним специализированного типа",
         "classTypeParametersIllegal": "Синтаксис параметра типа класса может использоваться в Python версии не ниже 3.12.",

packages/pyright-internal/src/localization/package.nls.tr.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ geçersiz kılması bir \"cls\" parametresi almalı",
         "classMethodClsParam": "Sınıf metotları bir \"cls\" parametresi almalıdır",
         "classNotRuntimeSubscriptable": "\"{name}\" sınıfına ait alt simge çalışma zamanı özel durumunu oluşturur; tür ek açıklamalarını tırnak içine alın",
-        "classPatternBuiltInArgCount": "Sınıf deseni en fazla 1 konumsal alt deseni kabul eder",
         "classPatternBuiltInArgPositional": "Sınıf deseni yalnızca konumsal alt desen kabul eder",
         "classPatternTypeAlias": "\"{type}\" özel bir tür diğer adı olduğundan sınıf deseninde kullanılamaz",
         "classTypeParametersIllegal": "Sınıf türü parametresi söz dizimi için Python 3.12 veya daha yeni bir sürümü gerekiyor",

packages/pyright-internal/src/localization/package.nls.zh-cn.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__替代应采用“cls”参数",
         "classMethodClsParam": "类方法应采用“cls”参数",
         "classNotRuntimeSubscriptable": "类“{name}”的下标将生成运行时异常；将类型批注括在引号中",
-        "classPatternBuiltInArgCount": "类模式最多接受 1 个位置子模式",
         "classPatternBuiltInArgPositional": "类模式仅接受位置子模式",
         "classPatternTypeAlias": "无法在类模式中使用“{type}”，因为它是专用类型别名",
         "classTypeParametersIllegal": "类类型参数语法需要 Python 3.12 或更高版本",

packages/pyright-internal/src/localization/package.nls.zh-tw.json

@@ -67,7 +67,6 @@
         "classGetItemClsParam": "__class_getitem__ 覆寫應接受 \"cls\" 參數",
         "classMethodClsParam": "類別方法應採用 \"cls\" 參數",
         "classNotRuntimeSubscriptable": "類別 \"{name}\" 的下標會產生執行階段例外; 以引號括住類型註釋",
-        "classPatternBuiltInArgCount": "類別模式最多接受 1 個位置子模式",
         "classPatternBuiltInArgPositional": "類別模式僅接受位置子模式",
         "classPatternTypeAlias": "無法在類別模式中使用 \"{type}\"，因為它是特殊的型別別名",
         "classTypeParametersIllegal": "類別類型參數語法需要 Python 3.12 或更新版本",

packages/pyright-internal/src/tests/samples/matchClass5.py

@@ -0,0 +1,63 @@
+# This sample tests the detection of too many positional patterns.
+
+from dataclasses import dataclass
+
+
+@dataclass
+class A:
+    a: int
+
+
+class B:
+    a: int
+    b: int
+
+    __match_args__ = ("a", "b")
+
+
+class C(B):
+    ...
+
+class D(int): ...
+
+def func1(subj: A | B):
+    match subj:
+        # This should generate an error because A accepts only
+        # one positional pattern.
+        case A(1, 2):
+            pass
+
+        case A(1):
+            pass
+
+        case A():
+            pass
+
+        case B(1, 2):
+            pass
+
+        # This should generate an error because B accepts only
+        # two positional patterns.
+        case B(1, 2, 3):
+            pass
+
+        # This should generate an error because B accepts only
+        # two positional patterns.
+        case C(1, 2, 3):
+            pass
+
+        case D(1):
+            pass
+
+        # This should generate an error because D accepts only
+        # one positional pattern.
+        case D(1, 2):
+            pass
+
+        case int(1):
+            pass
+
+        # This should generate an error because int accepts only
+        # one positional pattern.
+        case int(1, 2):
+            pass

packages/pyright-internal/src/tests/typeEvaluator3.test.ts

@@ -1248,6 +1248,14 @@ test('MatchClass4', () => {
     TestUtils.validateResults(analysisResults, 0);
 });
 
+test('MatchClass5', () => {
+    const configOptions = new ConfigOptions('.');
+
+    configOptions.defaultPythonVersion = PythonVersion.V3_10;
+    const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchClass5.py'], configOptions);
+    TestUtils.validateResults(analysisResults, 5);
+});
+
 test('MatchValue1', () => {
     const configOptions = new ConfigOptions('.');