[clang] [clang] Avoid printing overly large integer/_BitInt numbers in static assertion failure diagnostics #71675 (PR #145053)

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@@ -17575,7 +17576,21 @@ static bool ConvertAPValueToString(const APValue &V, QualType T,
           break;
         }
       }
-      V.getInt().toString(Str);
+
+      llvm::APSInt vInt = V.getInt();
+      if (llvm::APSInt::compareValues(
+              vInt, llvm::APSInt::getUnsigned(
+                        std::numeric_limits<uint64_t>::max())) >= 0 ||
+          vInt < std::numeric_limits<int64_t>::min()) {
+        // The value of cutSize is not special, it is just a number of
+        // characters that gives us enough info without losing readability
+        const int cutSize = 20;
+        vInt.toString(Str, 16);
+        Str.erase(Str.begin() + cutSize, Str.end() - cutSize);
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maramatias wrote:

Hi just wanted to run something by you before I make further changes. 
Before, we were using the value of the APInt to decide if we would truncate or not. I am tempted since we will be looking at the number of digits anyway to decide how many to skip to instead use that as the deciding factor, so something like, if the number of digits in the APInt value is larger than 40 (This is if we want to keep N=20) then we truncate keeping the first and last 20. 
Were you thinking of some other way to decide what N should be by the way?

https://github.com/llvm/llvm-project/pull/145053