Added missing check for a PEP 695 type parameter being the target of …

…a `nonlocal` statement. This results in a runtime exception, so it should be reported as an error. This addresses #9817. (#9821)
microsoft · Feb 5, 2025 · b28da12 · b28da12
1 parent b105a38
commit b28da12
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Showing 5 changed files with 38 additions and 2 deletions.
diff --git a/packages/pyright-internal/src/analyzer/checker.ts b/packages/pyright-internal/src/analyzer/checker.ts
@@ -1440,6 +1440,8 @@ export class Checker extends ParseTreeWalker {
                 this._evaluator.getType(name);
 
                 this.walk(name);
+
+                this._validateNonlocalTypeParam(name);
             });
         });
 
@@ -1909,6 +1911,22 @@ export class Checker extends ParseTreeWalker {
         }
     }
 
+    // Verifies that the target of a nonlocal statement is not a PEP 695-style
+    // TypeParameter. This situation results in a runtime exception.
+    private _validateNonlocalTypeParam(node: NameNode) {
+        // Look up the symbol to see if it's a type parameter.
+        const symbolWithScope = this._evaluator.lookUpSymbolRecursive(node, node.d.value, /* honorCodeFlow */ false);
+        if (!symbolWithScope || symbolWithScope.scope.type !== ScopeType.TypeParameter) {
+            return;
+        }
+
+        this._evaluator.addDiagnostic(
+            DiagnosticRule.reportGeneralTypeIssues,
+            LocMessage.nonlocalTypeParam().format({ name: node.d.value }),
+            node
+        );
+    }
+
     private _validateExhaustiveMatch(node: MatchNode) {
         // This check can be expensive, so skip it if it's disabled.
         if (this._fileInfo.diagnosticRuleSet.reportMatchNotExhaustive === 'none') {

diff --git a/packages/pyright-internal/src/localization/localize.ts b/packages/pyright-internal/src/localization/localize.ts
@@ -703,15 +703,17 @@ export namespace Localizer {
             new ParameterizedString<{ operator: string }>(getRawString('Diagnostic.noneOperator'));
         export const noneUnknownMember = () =>
             new ParameterizedString<{ name: string }>(getRawString('Diagnostic.noneUnknownMember'));
+        export const nonLocalInModule = () => getRawString('Diagnostic.nonLocalInModule');
         export const nonLocalNoBinding = () =>
             new ParameterizedString<{ name: string }>(getRawString('Diagnostic.nonLocalNoBinding'));
         export const nonLocalReassignment = () =>
             new ParameterizedString<{ name: string }>(getRawString('Diagnostic.nonLocalReassignment'));
         export const nonLocalRedefinition = () =>
             new ParameterizedString<{ name: string }>(getRawString('Diagnostic.nonLocalRedefinition'));
-        export const nonLocalInModule = () => getRawString('Diagnostic.nonLocalInModule');
         export const noOverload = () =>
             new ParameterizedString<{ name: string }>(getRawString('Diagnostic.noOverload'));
+        export const nonlocalTypeParam = () =>
+            new ParameterizedString<{ name: string }>(getRawString('Diagnostic.nonlocalTypeParam'));
         export const noReturnContainsReturn = () => getRawString('Diagnostic.noReturnContainsReturn');
         export const noReturnContainsYield = () => getRawString('Diagnostic.noReturnContainsYield');
         export const noReturnReturnsNone = () => getRawString('Diagnostic.noReturnReturnsNone');

diff --git a/packages/pyright-internal/src/localization/package.nls.en-us.json b/packages/pyright-internal/src/localization/package.nls.en-us.json
@@ -844,6 +844,10 @@
             "message": "\"{name}\" was already declared nonlocal",
             "comment": "{Locked='nonlocal'}"
         },
+        "nonlocalTypeParam": {
+            "message": "Nonlocal binding is not allowed for type parameter \"{name}\"",
+            "comment": ["{StrContains=i'nonlocal'}", "'nonlocal' is a keyword and should not be localized. It is only capitalized here because it is the first word in the sentence"]
+        },
         "noneNotCallable": {
             "message": "Object of type \"None\" cannot be called",
             "comment": "{Locked='None'}"

diff --git a/packages/pyright-internal/src/tests/samples/typeParams1.py b/packages/pyright-internal/src/tests/samples/typeParams1.py
@@ -101,3 +101,15 @@ def method2[T](self, v: ClassI3) -> None: ...
 
 
 class ClassI3: ...
+
+
+def func9[T, **P, S](x: T) -> T:
+    S = 1
+
+    def inner():
+        # This should generate two errors.
+        nonlocal T, P
+
+        nonlocal S
+
+    return x
diff --git a/packages/pyright-internal/src/tests/typeEvaluator5.test.ts b/packages/pyright-internal/src/tests/typeEvaluator5.test.ts
@@ -18,7 +18,7 @@ test('TypeParams1', () => {
     configOptions.defaultPythonVersion = pythonVersion3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeParams1.py'], configOptions);
-    TestUtils.validateResults(analysisResults, 6);
+    TestUtils.validateResults(analysisResults, 8);
 });
 
 test('TypeParams2', () => {