Avoid silently truncating BigInt to Int

- Introduce internal helper `castToInt`, which issues an error when the input
BigInt can't be represented as Int.

- Use `castToInt` wherever we were using `toInt` in a potentially unsafe way.

1 files changed, 9 insertions, 0 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
index 4105a699..1163171c 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
@@ -378,3 +378,12 @@ object DynamicNamingStack {
     prefixRef
   }
 }
+
+/** Casts BigInt to Int, issuing an error when the input isn't representable. */
+private[chisel3] object castToInt {
+  def apply(x: BigInt, msg: String): Int = {
+    val res = x.toInt
+    require(x == res, s"$msg $x is too large to be represented as Int")
+    res
+  }
+}