Deprecate numeric widening of Numeric Literals which are not represen…

…table with Float/Double
scala · Feb 26, 2020 · e88a7cb · e88a7cb
1 parent b1550dd
commit e88a7cb
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Showing 3 changed files with 40 additions and 4 deletions.
diff --git a/src/reflect/scala/reflect/internal/Constants.scala b/src/reflect/scala/reflect/internal/Constants.scala
@@ -63,7 +63,10 @@ trait Constants extends api.Constants {
     def isCharRange: Boolean  = isIntRange && Char.MinValue <= intValue && intValue <= Char.MaxValue
     def isIntRange: Boolean   = ByteTag <= tag && tag <= IntTag
     def isLongRange: Boolean  = ByteTag <= tag && tag <= LongTag
-    def isFloatRange: Boolean = ByteTag <= tag && tag <= FloatTag
+    // Float has a Fraction of 23 Bits + 1 implicit leading Bit so the total precision is 24 Bit (see https://en.wikipedia.org/wiki/Single-precision_floating-point_format)
+    def isFloatRepresentable: Boolean = ByteTag <= tag && tag <= FloatTag && (tag != IntTag && tag != LongTag || longValue <= (1L << 24) && longValue >= -(1L << 24))
+    // Double has a Fraction of 53 Bits + 1 implicit leading Bit => 54 Bit
+    def isDoubleRepresentable: Boolean    = ByteTag <= tag && tag <= DoubleTag && (tag != LongTag || longValue <= (1L << 54) && longValue >= -(1L << 54))
     def isNumeric: Boolean    = ByteTag <= tag && tag <= DoubleTag
     def isNonUnitAnyVal       = BooleanTag <= tag && tag <= DoubleTag
     def isSuitableLiteralType = BooleanTag <= tag && tag <= NullTag
@@ -218,9 +221,9 @@ trait Constants extends api.Constants {
         Constant(intValue)
       else if (target == LongClass && isLongRange)
         Constant(longValue)
-      else if (target == FloatClass && isFloatRange)
+      else if (target == FloatClass && isFloatRepresentable)
         Constant(floatValue)
-      else if (target == DoubleClass && isNumeric)
+      else if (target == DoubleClass && isDoubleRepresentable)
         Constant(doubleValue)
       else
         null

diff --git a/test/files/neg/deprecated_widening.check b/test/files/neg/deprecated_widening.check
@@ -7,6 +7,24 @@ deprecated_widening.scala:7: warning: Automatic conversion from Long to Float is
 deprecated_widening.scala:8: warning: Automatic conversion from Long to Double is deprecated (since 2.13.1) because it loses precision. Write `.toDouble` instead.
     val l_d: Double = l // deprecated
                       ^
+deprecated_widening.scala:23: warning: Automatic conversion from Long to Float is deprecated (since 2.13.1) because it loses precision. Write `.toFloat` instead.
+  val truncatedPosFloat:Float = 16777217L  // deprecated
+                                ^
+deprecated_widening.scala:25: warning: Automatic conversion from Long to Float is deprecated (since 2.13.1) because it loses precision. Write `.toFloat` instead.
+  val truncatedNegFloat: Float = - 16777217L // deprecated
+                                 ^
+deprecated_widening.scala:28: warning: Automatic conversion from Int to Float is deprecated (since 2.13.1) because it loses precision. Write `.toFloat` instead.
+  val truncatedPosFloatI:Float = 16777217  // deprecated
+                                 ^
+deprecated_widening.scala:30: warning: Automatic conversion from Int to Float is deprecated (since 2.13.1) because it loses precision. Write `.toFloat` instead.
+  val truncatedNegFloatI: Float = - 16777217 // deprecated
+                                  ^
+deprecated_widening.scala:33: warning: Automatic conversion from Long to Double is deprecated (since 2.13.1) because it loses precision. Write `.toDouble` instead.
+  val truncatedPosDouble:Double = 18014398509481985L // deprecated
+                                  ^
+deprecated_widening.scala:35: warning: Automatic conversion from Long to Double is deprecated (since 2.13.1) because it loses precision. Write `.toDouble` instead.
+  val truncatedNegDouble: Double = - 18014398509481985L // deprecated
+                                   ^
 deprecated_widening.scala:12: warning: method int2float in object Int is deprecated (since 2.13.1): Implicit conversion from Int to Float is dangerous because it loses precision. Write `.toFloat` instead.
     implicitly[Int => Float]   // deprecated
               ^
@@ -17,5 +35,5 @@ deprecated_widening.scala:15: warning: method long2double in object Long is depr
     implicitly[Long => Double] // deprecated
               ^
 error: No warnings can be incurred under -Werror.
-6 warnings
+12 warnings
 1 error
diff --git a/test/files/neg/deprecated_widening.scala b/test/files/neg/deprecated_widening.scala
@@ -18,4 +18,19 @@ object Test {
   // don't leak silent warning from float conversion
   val n = 42
   def clean = n max 27
+
+  val posFloat:Float = 16777216L  // OK
+  val truncatedPosFloat:Float = 16777217L  // deprecated
+  val negFloat: Float = - 16777216L // OK
+  val truncatedNegFloat: Float = - 16777217L // deprecated
+
+  val posFloatI:Float = 16777216  // OK
+  val truncatedPosFloatI:Float = 16777217  // deprecated
+  val negFloatI: Float = - 16777216 // OK
+  val truncatedNegFloatI: Float = - 16777217 // deprecated
+
+  val posDouble:Double = 18014398509481984L// OK
+  val truncatedPosDouble:Double = 18014398509481985L // deprecated
+  val negDouble: Double = - 18014398509481984L // OK
+  val truncatedNegDouble: Double = - 18014398509481985L // deprecated
 }