factoring out logic to check for overflows during coercions

src/Overflow.h

@@ -0,0 +1,33 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#pragma once
+
+#include "zeek/Type.h"
+
+namespace zeek::detail {
+
+inline bool double_to_count_would_overflow(double v)
+	{
+	return v < 0.0 || v > static_cast<double>(UINT64_MAX);
+	}
+
+inline bool int_to_count_would_overflow(bro_int_t v)
+	{
+	return v < 0.0;
+	}
+
+inline bool double_to_int_would_overflow(double v)
+	{
+	return v < static_cast<double>(INT64_MIN) ||
+	       v > static_cast<double>(INT64_MAX);
+	}
+
+inline bool count_to_int_would_overflow(bro_uint_t v)
+	{
+	return v > INT64_MAX;
+	}
+
+extern bool would_overflow(const zeek::Type* from_type,
+                           const zeek::Type* to_type, const Val* val);
+
+}