[clang] [Clang] Treat the body of an expansion statement with expansion size 0 as discarded (PR #212319)

[Oliver Hunt via cfe-commits]

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@@ -1760,12 +1760,15 @@ void ASTStmtWriter::VisitCXXForRangeStmt(CXXForRangeStmt *S) {
 void ASTStmtWriter::VisitCXXExpansionStmtPattern(CXXExpansionStmtPattern *S) {
   VisitStmt(S);
   Record.push_back(static_cast<unsigned>(S->getKind()));
+  Record.push_back(S->getExpansionSize().has_value());
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ojhunt wrote:

obviously a `readBool` would imply `writeBool` would be required here

https://github.com/llvm/llvm-project/pull/212319