fix Never type aliases being coloured as a variable when using the new python 3.12 type alias syntax

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

@@ -1,6 +1,6 @@
 import { ParseTreeWalker } from './parseTreeWalker';
 import { TypeEvaluator } from './typeEvaluatorTypes';
-import { FunctionType, OverloadedFunctionType, Type, TypeCategory, TypeFlags } from './types';
+import { ClassType, FunctionType, OverloadedFunctionType, Type, TypeCategory, TypeFlags } from './types';
 import {
     ClassNode,
     DecoratorNode,
@@ -206,12 +206,14 @@ export class SemanticTokensWalker extends ParseTreeWalker {
         }
         const symbol = this._evaluator?.lookUpSymbolRecursive(node, node.value, false)?.symbol;
         if (type?.category === TypeCategory.Never && symbol) {
-            // for some reason Never is considered both instantiable and an instance, so we need a way
-            // to differentiate between "instances" of `Never` and type aliases/annotations of Never.
-            // this is probably extremely cringe since i have no idea what this is doing and i literally
-            // just brute forced random shit until all the tests passed
             const typeResult = this._evaluator?.getEffectiveTypeOfSymbolForUsage(symbol, node);
             if (
+                // check for new python 3.12 type alias syntax
+                (typeResult.type.specialForm && ClassType.isBuiltIn(typeResult.type.specialForm, 'TypeAliasType')) ||
+                // for some reason Never is considered both instantiable and an instance, so we need a way
+                // to differentiate between "instances" of `Never` and type aliases/annotations of Never.
+                // this is probably extremely cringe since i have no idea what this is doing and i literally
+                // just brute forced random shit until all the tests passed
                 (typeResult.type.category !== TypeCategory.Never &&
                     typeResult.type.category !== TypeCategory.Unbound &&
                     typeResult.type.flags & TypeFlags.Instantiable) ||

packages/pyright-internal/src/tests/samples/semantic_highlighting/never.py

@@ -20,4 +20,7 @@ def inferred():
 
     value2: str = ''
     if not isinstance(value2, str):
-        value2
+        value2
+
+type Baz = Never
+baz: Baz

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

@@ -86,6 +86,11 @@ if (process.platform !== 'win32' || !process.env['CI']) {
             { type: 'variable', modifiers: [], start: 293, length: 6 }, // value2
             { type: 'class', modifiers: ['defaultLibrary', 'builtin'], start: 301, length: 3 }, // str
             { type: 'variable', modifiers: [], start: 315, length: 6 }, // value2
+            { type: 'keyword', modifiers: [], start: 323, length: 4 }, // type
+            { type: 'type', modifiers: [], start: 328, length: 3 }, // Baz
+            { type: 'type', modifiers: [], start: 334, length: 5 }, // Never
+            { type: 'variable', modifiers: [], start: 340, length: 3 }, // baz
+            { type: 'type', modifiers: [], start: 345, length: 3 }, // Baz
         ]);
     });