Ensure that contents and valid apply to individual elements

Resolves kaitai-io/kaitai_struct#1117

This is how the `contents` key worked until KS 0.8, but then in KS 0.9,
`contents` started to be converted to the newly introduced `valid`,
which was applied only once at the end on the final value. This means
that it was applied on the entire array in the case of repeated fields.
However, the behavior of `valid` + `repeat` wasn't tested anywhere, so I
think it was an oversight. Note that the Kaitai Struct language doesn't
define an equality `==` operation for true arrays, so it wouldn't even
work. Running the `valid` and `contents` checks on each element is more
flexible (and also seems more useful).

Fixes the following tests for all languages except Go (will be fixed in
the following commit), Nim, Perl and Construct:

* ValidFailRepeatAnyofInt
* ValidFailRepeatContents
* ValidFailRepeatEqInt
* ValidFailRepeatExpr
* ValidFailRepeatInst
* ValidFailRepeatMaxInt
* ValidFailRepeatMinInt

These tests were added in
kaitai-io/kaitai_struct_tests@98a68fc

shared/src/main/scala/io/kaitai/struct/format/Identifier.scala

@@ -70,6 +70,19 @@ object Identifier {
     }
   }
 
+  def itemExpr(id: Identifier, rep: RepeatSpec): Ast.expr = {
+    val astId = Ast.expr.InternalName(id)
+    rep match {
+      case NoRepeat =>
+        astId
+      case _ =>
+        Ast.expr.Subscript(
+          astId,
+          Ast.expr.Name(Ast.identifier(Identifier.INDEX))
+        )
+    }
+  }
+
   // Constants for special names used in expression language
   val ROOT = "_root"
   val PARENT = "_parent"

shared/src/main/scala/io/kaitai/struct/languages/components/CommonReads.scala

@@ -60,9 +60,6 @@ trait CommonReads extends LanguageCompiler {
       case _ => // no seeking required for sequence attributes
     }
 
-    // Run validations (still inside "if", if applicable)
-    attrValidateAll(attr)
-
     attrParseIfFooter(attr.cond.ifExpr)
   }
 
@@ -79,6 +76,7 @@ trait CommonReads extends LanguageCompiler {
       case NoRepeat =>
     }
     attrParse2(id, attr.dataType, io, attr.cond.repeat, false, defEndian)
+    attrValidateAll(attr)
     attr.cond.repeat match {
       case RepeatEos =>
         condRepeatEosFooter

shared/src/main/scala/io/kaitai/struct/languages/components/ValidateOps.scala

@@ -14,22 +14,23 @@ trait ValidateOps extends ExceptionNames {
   val typeProvider: ClassTypeProvider
 
   def attrValidate(attrId: Identifier, attr: AttrLikeSpec, valid: ValidationSpec): Unit = {
+    val itemValue = Identifier.itemExpr(attrId, attr.cond.repeat)
     valid match {
       case ValidationEq(expected) =>
-        attrValidateExprCompare(attrId, attr, Ast.cmpop.Eq, expected, ValidationNotEqualError(attr.dataTypeComposite))
+        attrValidateExprCompare(attrId, attr, Ast.cmpop.Eq, expected, ValidationNotEqualError(attr.dataType))
       case ValidationMin(min) =>
-        attrValidateExprCompare(attrId, attr, Ast.cmpop.GtE, min, ValidationLessThanError(attr.dataTypeComposite))
+        attrValidateExprCompare(attrId, attr, Ast.cmpop.GtE, min, ValidationLessThanError(attr.dataType))
       case ValidationMax(max) =>
-        attrValidateExprCompare(attrId, attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attr.dataTypeComposite))
+        attrValidateExprCompare(attrId, attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attr.dataType))
       case ValidationRange(min, max) =>
-        attrValidateExprCompare(attrId, attr, Ast.cmpop.GtE, min, ValidationLessThanError(attr.dataTypeComposite))
-        attrValidateExprCompare(attrId, attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attr.dataTypeComposite))
+        attrValidateExprCompare(attrId, attr, Ast.cmpop.GtE, min, ValidationLessThanError(attr.dataType))
+        attrValidateExprCompare(attrId, attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attr.dataType))
       case ValidationAnyOf(values) =>
         val bigOrExpr = Ast.expr.BoolOp(
           Ast.boolop.Or,
           values.map(expected =>
             Ast.expr.Compare(
-              Ast.expr.InternalName(attrId),
+              itemValue,
               Ast.cmpop.Eq,
               expected
             )
@@ -38,30 +39,30 @@ trait ValidateOps extends ExceptionNames {
 
         attrValidateExpr(
           attrId,
-          attr.dataTypeComposite,
+          attr.dataType,
           checkExpr = bigOrExpr,
-          err = ValidationNotAnyOfError(attr.dataTypeComposite),
+          err = ValidationNotAnyOfError(attr.dataType),
           errArgs = List(
-            Ast.expr.InternalName(attrId),
+            itemValue,
             Ast.expr.InternalName(IoIdentifier),
             Ast.expr.Str(attr.path.mkString("/", "/", ""))
           )
         )
       case ValidationExpr(expr) =>
         blockScopeHeader
-        typeProvider._currentIteratorType = Some(attr.dataTypeComposite)
+        typeProvider._currentIteratorType = Some(attr.dataType)
         handleAssignmentTempVar(
-          attr.dataTypeComposite,
+          attr.dataType,
           translator.translate(Ast.expr.Name(Ast.identifier(Identifier.ITERATOR))),
-          translator.translate(Ast.expr.InternalName(attrId))
+          translator.translate(itemValue)
         )
         attrValidateExpr(
           attrId,
-          attr.dataTypeComposite,
+          attr.dataType,
           expr,
-          ValidationExprError(attr.dataTypeComposite),
+          ValidationExprError(attr.dataType),
           List(
-            Ast.expr.InternalName(attrId),
+            itemValue,
             Ast.expr.InternalName(IoIdentifier),
             Ast.expr.Str(attr.path.mkString("/", "/", ""))
           )
@@ -71,18 +72,19 @@ trait ValidateOps extends ExceptionNames {
   }
 
   def attrValidateExprCompare(attrId: Identifier, attr: AttrLikeSpec, op: Ast.cmpop, expected: Ast.expr, err: KSError): Unit = {
+    val itemValue = Identifier.itemExpr(attrId, attr.cond.repeat)
     attrValidateExpr(
       attrId,
-      attr.dataTypeComposite,
+      attr.dataType,
       checkExpr = Ast.expr.Compare(
-        Ast.expr.InternalName(attrId),
+        itemValue,
         op,
         expected
       ),
       err = err,
       errArgs = List(
         expected,
-        Ast.expr.InternalName(attrId),
+        itemValue,
         Ast.expr.InternalName(IoIdentifier),
         Ast.expr.Str(attr.path.mkString("/", "/", ""))
       )