Disallow chained apply (#380)

3 files changed, 15 insertions, 11 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala b/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
index 8fdcb260..17354799 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
@@ -126,7 +126,7 @@ object Vec {
     if (n <= 1) 0.U
     else if (idx.width.known && idx.width.get <= w) idx
     else if (idx.width.known) idx(w-1,0)
-    else (idx | 0.U(w))(w-1,0)
+    else (idx | 0.U(w.W))(w-1,0)
   }
 }
 
diff --git a/chiselFrontend/src/main/scala/chisel3/core/Bits.scala b/chiselFrontend/src/main/scala/chisel3/core/Bits.scala
index 354512e1..cab1a82e 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Bits.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Bits.scala
@@ -478,7 +478,7 @@ sealed class UInt private[core] (width: Width, lit: Option[ULit] = None)
 
   final def unary_! () : Bool = macro SourceInfoTransform.noArg
 
-  def do_unary_! (implicit sourceInfo: SourceInfo) : Bool = this === 0.U(1)
+  def do_unary_! (implicit sourceInfo: SourceInfo) : Bool = this === 0.U(1.W)
 
   override def do_<< (that: Int)(implicit sourceInfo: SourceInfo): UInt =
     binop(sourceInfo, UInt(this.width + that), ShiftLeftOp, that)
@@ -496,7 +496,7 @@ sealed class UInt private[core] (width: Width, lit: Option[ULit] = None)
   final def bitSet(off: UInt, dat: Bool): UInt = macro UIntTransform.bitset
 
   def do_bitSet(off: UInt, dat: Bool)(implicit sourceInfo: SourceInfo): UInt = {
-    val bit = 1.U(1) << off
+    val bit = 1.U(1.W) << off
     Mux(dat, this | bit, ~(~this | bit))
   }
 
diff --git a/chiselFrontend/src/main/scala/chisel3/core/package.scala b/chiselFrontend/src/main/scala/chisel3/core/package.scala
index 77f35c23..1d5817ae 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/package.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/package.scala
@@ -16,14 +16,18 @@ package chisel3 {
     * after this call using apply, ie. 0.asUInt(1)(0) due to potential for
     * confusion (the 1 is a bit length and the 0 is a bit extraction position).
     * Prefer storing the result and then extracting from it.
+    *
+    * Implementation note: the empty parameter list (like `U()`) is necessary to prevent
+    * interpreting calls that have a non-Width parameter as a chained apply, otherwise things like
+    * `0.asUInt(16)` (instead of `16.W`) compile without error and produce undesired results.
     */
     implicit class fromBigIntToLiteral(val bigint: BigInt) {
       /** Int to UInt conversion, recommended style for constants.
         */
-      def U: UInt = UInt.Lit(bigint, Width())  // scalastyle:ignore method.name
+      def U(): UInt = UInt.Lit(bigint, Width())  // scalastyle:ignore method.name
       /** Int to SInt conversion, recommended style for constants.
         */
-      def S: SInt = SInt.Lit(bigint, Width())  // scalastyle:ignore method.name
+      def S(): SInt = SInt.Lit(bigint, Width())  // scalastyle:ignore method.name
       /** Int to UInt conversion with specified width, recommended style for constants.
         */
       def U(width: Width): UInt = UInt.Lit(bigint, width)  // scalastyle:ignore method.name
@@ -33,10 +37,10 @@ package chisel3 {
 
       /** Int to UInt conversion, recommended style for variables.
         */
-      def asUInt: UInt = UInt.Lit(bigint, Width())
+      def asUInt(): UInt = UInt.Lit(bigint, Width())
       /** Int to SInt conversion, recommended style for variables.
         */
-      def asSInt: SInt = SInt.Lit(bigint, Width())
+      def asSInt(): SInt = SInt.Lit(bigint, Width())
       /** Int to UInt conversion with specified width, recommended style for variables.
         */
       def asUInt(width: Width): UInt = UInt.Lit(bigint, width)
@@ -51,14 +55,14 @@ package chisel3 {
     implicit class fromStringToLiteral(val str: String) {
       /** String to UInt parse, recommended style for constants.
         */
-      def U: UInt = UInt.Lit(parse(str), parsedWidth(str))  // scalastyle:ignore method.name
+      def U(): UInt = UInt.Lit(parse(str), parsedWidth(str))  // scalastyle:ignore method.name
       /** String to UInt parse with specified width, recommended style for constants.
         */
       def U(width: Width): UInt = UInt.Lit(parse(str), width)  // scalastyle:ignore method.name
 
       /** String to UInt parse, recommended style for variables.
         */
-      def asUInt: UInt = UInt.Lit(parse(str), parsedWidth(str))
+      def asUInt(): UInt = UInt.Lit(parse(str), parsedWidth(str))
       /** String to UInt parse with specified width, recommended style for variables.
         */
       def asUInt(width: Width): UInt = UInt.Lit(parse(str), width)
@@ -88,11 +92,11 @@ package chisel3 {
     implicit class fromBooleanToLiteral(val boolean: Boolean) {
       /** Boolean to Bool conversion, recommended style for constants.
         */
-      def B: Bool = Bool.Lit(boolean)  // scalastyle:ignore method.name
+      def B(): Bool = Bool.Lit(boolean)  // scalastyle:ignore method.name
 
       /** Boolean to Bool conversion, recommended style for variables.
         */
-      def asBool: Bool = Bool.Lit(boolean)
+      def asBool(): Bool = Bool.Lit(boolean)
     }
 
     implicit class fromDoubleToLiteral(val double: Double) {