[flang-commits] [flang] [flang][runtime] Fix integer overflow check in FORMAT (PR #79368)

[via flang-commits]

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@@ -214,15 +215,13 @@ template <typename CHAR> void FormatValidator<CHAR>::NextToken() {
   case '7':
   case '8':
   case '9': {
-    int64_t lastValue;
     const CHAR *lastCursor;
     integerValue_ = 0;
     bool overflow{false};
     do {
-      lastValue = integerValue_;
       lastCursor = cursor_;
       integerValue_ = 10 * integerValue_ + c - '0';
-      if (lastValue > integerValue_) {
+      if (integerValue_ > std::numeric_limits<int>::max()) {
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vdonaldson wrote:

Yes. So what should be a positive value becomes negative on overflow. If the type were unsigned, the overflow value would be positive but smaller. I think both signed and unsigned underlying types have this property. (It's been a long time since I looked at this in detail.)

https://github.com/llvm/llvm-project/pull/79368