Add check that floating point numbers are not too small

Author: Jentsch

compiler/src/dotty/tools/dotc/parsing/JavaScanners.scala

@@ -521,7 +521,7 @@ object JavaScanners {
       case FLOATLIT =>
         "float(" + floatVal + ")"
       case DOUBLELIT =>
-        "double(" + floatVal + ")"
+        "double(" + doubleVal + ")"
       case STRINGLIT =>
         "string(" + name + ")"
       case SEMI =>

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -726,7 +726,7 @@ object Parsers {
           case INTLIT                 => in.intVal(isNegated).toInt
           case LONGLIT                => in.intVal(isNegated)
           case FLOATLIT               => in.floatVal(isNegated).toFloat
-          case DOUBLELIT              => in.floatVal(isNegated)
+          case DOUBLELIT              => in.doubleVal(isNegated)
           case STRINGLIT | STRINGPART => in.strVal
           case TRUE                   => true
           case FALSE                  => false

compiler/src/dotty/tools/dotc/parsing/Scanners.scala

@@ -157,16 +157,42 @@ object Scanners {
 
     def intVal: Long = intVal(false)
 
+    private val zeroFloat = raw"[0.]+(?:[eE][+-]?[0-9]+)?[fFdD]?".r
+
     /** Convert current strVal, base to double value
       */
-    def floatVal(negated: Boolean): Double = {
+    def floatVal(negated: Boolean): Float = {
+      assert(token == FLOATLIT)
+      val text = removeNumberSeparators(strVal)
+      try {
+        val value: Float = java.lang.Float.valueOf(text).floatValue()
+        if (value > Float.MaxValue)
+          errorButContinue("floating point number too large")
+
+        if (value == 0.0f && !zeroFloat.pattern.matcher(text).matches)
+          errorButContinue("floating point number too small")
+        if (negated) -value else value
+      } catch {
+        case _: NumberFormatException =>
+          error("malformed floating point number")
+          0.0f
+      }
+    }
+
+    def floatVal: Float = floatVal(false)
+
+    /** Convert current strVal, base to double value
+      */
+    def doubleVal(negated: Boolean): Double = {
+      assert(token == DOUBLELIT)
       val text = removeNumberSeparators(strVal)
-      val limit: Double =
-        if (token == DOUBLELIT) Double.MaxValue else Float.MaxValue
       try {
         val value: Double = java.lang.Double.valueOf(text).doubleValue()
-        if (value > limit)
-          error("floating point number too large")
+        if (value > Double.MaxValue)
+          errorButContinue("double precision floating point number too large")
+
+        if (value == 0.0d && !zeroFloat.pattern.matcher(text).matches)
+          errorButContinue("double precision floating point number too small")
         if (negated) -value else value
       } catch {
         case _: NumberFormatException =>
@@ -175,7 +201,7 @@ object Scanners {
       }
     }
 
-    def floatVal: Double = floatVal(false)
+    def doubleVal: Double = doubleVal(false)
 
     @inline def isNumberSeparator(c: Char): Boolean = c == '_'
 
@@ -1034,7 +1060,7 @@ object Scanners {
       case INTLIT => s"int($intVal)"
       case LONGLIT => s"long($intVal)"
       case FLOATLIT => s"float($floatVal)"
-      case DOUBLELIT => s"double($floatVal)"
+      case DOUBLELIT => s"double($doubleVal)"
       case STRINGLIT => s"string($strVal)"
       case STRINGPART => s"stringpart($strVal)"
       case INTERPOLATIONID => s"interpolationid($name)"

tests/neg/t6124.check

@@ -1,3 +1,5 @@
+<304..304> in t6124.scala
+double precision floating point number too small
 <273..273> in t6124.scala
 trailing separator is not allowed
 <235..235> in t6124.scala

tests/neg/t6124.scala

@@ -12,5 +12,7 @@ trait T {
   def r = 3.1_4_dd // error // error
   def s = 3_.1 // error
 
+  def tooSmall = 1.0E-325 // error
+
   def z = 0
 }