[clang] [Clang] omit parentheses in fold expressions with a single expansion (PR #110761)

[via cfe-commits]

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@@ -2171,10 +2171,15 @@ class ParenExpr : public Expr {
   SourceLocation L, R;
   Stmt *Val;
 public:
+  enum TransformConstraint : uint8_t {
+    None = 0,     // No specific preservation required
+    Preserve = 1, // Parentheses have always to be preserved
+  };
+
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cor3ntin wrote:

I'm not sure that we need an enum here, i guess me and @erichkeane disagree!
Either way we should try to minimize the memory footprint of this feature.
One way to do that would be to introduce a `ParenExprBitFiled` in Stmt.h

You will also need to modify AstStmtReader / AstStmtWriter to make sure that gets serialized

I think the name should probably be something like "ProducedByFoldExpansion".

https://github.com/llvm/llvm-project/pull/110761