Clarify error messages when passing owned asset references to shared …

…inputs.
mcoblenz · Sep 1, 2019 · 7f083d5 · 7f083d5
1 parent 31bc252
commit 7f083d5
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Showing 3 changed files with 14 additions and 5 deletions.
diff --git a/src/main/scala/edu/cmu/cs/obsidian/typecheck/Checker.scala b/src/main/scala/edu/cmu/cs/obsidian/typecheck/Checker.scala
@@ -1251,7 +1251,7 @@ class Checker(globalTable: SymbolTable, verbose: Boolean = false) {
             if (passedType.isOwned && initialType.permission == Shared() && !finalType.isOwned &&
                 passedType.isAssetReference(context.contractTable) != No()) {
                 // Special case: passing an owned reference to a Shared >> Unowned arg will make the arg Unowned but also lose ownership!
-                logError(arg, UnusedExpressionArgumentOwnershipError(arg))
+                logError(arg, LostOwnershipErrorDueToSharing(arg))
             }
 
             if (context.get(referenceIdentifier).isDefined) {
@@ -1288,7 +1288,12 @@ class Checker(globalTable: SymbolTable, verbose: Boolean = false) {
                 if (argType.isOwned && argType.isAssetReference(context.contractTable) != No() &&
                     (declaredFinalType.isOwned || !declaredInitialType.isOwned))
                 {
-                    logError(arg, UnusedExpressionArgumentOwnershipError(arg))
+                    if (declaredInitialType.permission == Shared()) {
+                        logError(arg, LostOwnershipErrorDueToSharing(arg))
+                    }
+                    else {
+                        logError(arg, UnusedExpressionArgumentOwnershipError(arg))
+                    }
                 }
                 None
         }

diff --git a/src/main/scala/edu/cmu/cs/obsidian/typecheck/Error.scala b/src/main/scala/edu/cmu/cs/obsidian/typecheck/Error.scala
@@ -184,6 +184,10 @@ case class UnusedExpressionArgumentOwnershipError(e: Expression) extends Error {
     val msg: String = s"Expression '$e' holds ownership, but is passed as an argument to a transaction that did not consume ownership."
 }
 
+case class LostOwnershipErrorDueToSharing(e: Expression) extends Error {
+    val msg: String = s"Expression '$e' holds ownership, but is passed as an argument to a transaction that causes it to become Shared, losing ownership."
+}
+
 case class PotentiallyUnusedOwnershipError(name: String) extends Error {
     val msg: String = s"Variable '$name' holds ownership, but may be unused at the end of its scope."
 }

diff --git a/src/test/scala/edu/cmu/cs/obsidian/tests/TypeCheckerTests.scala b/src/test/scala/edu/cmu/cs/obsidian/tests/TypeCheckerTests.scala
@@ -886,7 +886,7 @@ class TypeCheckerTests extends JUnitSuite {
                 ContractReferenceType(ContractType("PermissionPassing", Nil), Unowned(), false),
                 ContractReferenceType(ContractType("PermissionPassing", Nil), Owned(), false)), 47) ::
                 (UnusedExpressionArgumentOwnershipError(LocalInvocation("returnOwnedAsset", Nil, Nil, Nil)), 58) ::
-                (UnusedExpressionArgumentOwnershipError(LocalInvocation("returnOwnedAsset", Nil, Nil, Nil)), 65) ::
+                (LostOwnershipErrorDueToSharing(LocalInvocation("returnOwnedAsset", Nil, Nil, Nil)), 65) ::
                 Nil)
     }
 
@@ -898,8 +898,8 @@ class TypeCheckerTests extends JUnitSuite {
                     ContractReferenceType(ContractType("AllPermissions", Nil), Owned(), false), false), 25) ::
                 (SubtypingError(ContractReferenceType(ContractType("AllPermissions", Nil), Unowned(), false),
                     ContractReferenceType(ContractType("AllPermissions", Nil), Shared(), false), false), 29) ::
-                (UnusedExpressionArgumentOwnershipError(ReferenceIdentifier("x2")), 41) ::
-                (UnusedExpressionArgumentOwnershipError(ReferenceIdentifier("x7")), 63) ::
+                (LostOwnershipErrorDueToSharing(ReferenceIdentifier("x2")), 41) ::
+                (LostOwnershipErrorDueToSharing(ReferenceIdentifier("x7")), 63) ::
                 (ReceiverTypeIncompatibleError("t1",
                     ContractReferenceType(ContractType("AllPermissions", Nil), Shared(), false),
                     ContractReferenceType(ContractType("AllPermissions", Nil), Owned(), false)), 81) ::