Fix and validate post-increment/decrement in module emit (#44968)

Author: rbuckton

src/compiler/factory/nodeFactory.ts

@@ -2724,6 +2724,14 @@ namespace ts {
             node.operator = operator;
             node.operand = parenthesizerRules().parenthesizeOperandOfPrefixUnary(operand);
             node.transformFlags |= propagateChildFlags(node.operand);
+            // Only set this flag for non-generated identifiers and non-"local" names. See the
+            // comment in `visitPreOrPostfixUnaryExpression` in module.ts
+            if ((operator === SyntaxKind.PlusPlusToken || operator === SyntaxKind.MinusMinusToken) &&
+                isIdentifier(node.operand) &&
+                !isGeneratedIdentifier(node.operand) &&
+                !isLocalName(node.operand)) {
+                node.transformFlags |= TransformFlags.ContainsUpdateExpressionForIdentifier;
+            }
             return node;
         }
 
@@ -2739,7 +2747,14 @@ namespace ts {
             const node = createBaseExpression<PostfixUnaryExpression>(SyntaxKind.PostfixUnaryExpression);
             node.operator = operator;
             node.operand = parenthesizerRules().parenthesizeOperandOfPostfixUnary(operand);
-            node.transformFlags = propagateChildFlags(node.operand);
+            node.transformFlags |= propagateChildFlags(node.operand);
+            // Only set this flag for non-generated identifiers and non-"local" names. See the
+            // comment in `visitPreOrPostfixUnaryExpression` in module.ts
+            if (isIdentifier(node.operand) &&
+                !isGeneratedIdentifier(node.operand) &&
+                !isLocalName(node.operand)) {
+                node.transformFlags |= TransformFlags.ContainsUpdateExpressionForIdentifier;
+            }
             return node;
         }
 

src/compiler/transformers/module/module.ts

@@ -6640,6 +6640,7 @@ namespace ts {
         ContainsClassFields = 1 << 23,
         ContainsPossibleTopLevelAwait = 1 << 24,
         ContainsLexicalSuper = 1 << 25,
+        ContainsUpdateExpressionForIdentifier = 1 << 26,
         // Please leave this as 1 << 29.
         // It is the maximum bit we can set before we outgrow the size of a v8 small integer (SMI) on an x86 system.
         // It is a good reminder of how much room we have left