Fix: Correctly flag always-truthy exported and imported enum conditions (ts2845)

internal/checker/checker.go

@@ -3829,10 +3829,17 @@ func (c *Checker) checkTestingKnownTruthyType(condExpr *ast.Node, condType *Type
 	if location != condExpr {
 		t = c.checkExpression(location)
 	}
-	if t.flags&TypeFlagsEnumLiteral != 0 && ast.IsPropertyAccessExpression(location) && core.OrElse(c.getResolvedSymbolOrNil(location.Expression()), c.unknownSymbol).Flags&ast.SymbolFlagsEnum != 0 {
-		// EnumLiteral type at condition with known value is always truthy or always falsy, likely an error
-		c.error(location, diagnostics.This_condition_will_always_return_0, core.IfElse(evaluator.IsTruthy(t.AsLiteralType().value), "true", "false"))
-		return
+	if t.flags&TypeFlagsEnumLiteral != 0 && ast.IsPropertyAccessExpression(location) {
+		exprSymbol := core.OrElse(c.getResolvedSymbolOrNil(location.Expression()), c.unknownSymbol)
+		if exprSymbol.Flags&ast.SymbolFlagsAlias != 0 {
+			exprSymbol = c.resolveAlias(exprSymbol)
+		}
+		exprSymbol = c.getExportSymbolOfValueSymbolIfExported(exprSymbol)
+		if exprSymbol.Flags&ast.SymbolFlagsEnum != 0 {
+			// EnumLiteral type at condition with known value is always truthy or always falsy, likely an error
+			c.error(location, diagnostics.This_condition_will_always_return_0, core.IfElse(evaluator.IsTruthy(t.AsLiteralType().value), "true", "false"))
+			return
+		}
 	}
 	isPropertyExpressionCast := ast.IsPropertyAccessExpression(location) && isTypeAssertion(location.Expression())
 	if !c.hasTypeFacts(t, TypeFactsTruthy) || isPropertyExpressionCast {

testdata/tests/cases/compiler/exportEnumConditionAlwaysTrue.ts

@@ -0,0 +1,25 @@
+module A {
+  export enum ExportedEnum {
+    APP_PAGE = 1,
+    PAGES = 2,
+  }
+}
+
+import ImportedEnum = A.ExportedEnum;
+
+// Test 1: Exported enum directly
+declare const type1: A.ExportedEnum;
+const kind1 = type1 === A.ExportedEnum.APP_PAGE || A.ExportedEnum.PAGES ? 'left' : 'right';
+
+// Test 2: Imported enum alias
+declare const type2: ImportedEnum;
+const kind2 = type2 === ImportedEnum.APP_PAGE || ImportedEnum.PAGES ? 'left' : 'right';
+
+// Test 3: Normal enum (baseline verification)
+enum NormalEnum {
+  A = 1,
+  B = 2,
+}
+
+declare const type3: NormalEnum;
+const kind3 = type3 === NormalEnum.A || NormalEnum.B ? 'left' : 'right';