fix borrowing of capability without type argument

onflow · Jul 10, 2020 · 37a5460 · 37a5460
1 parent 4d10cd0
commit 37a5460
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Showing 2 changed files with 22 additions and 4 deletions.
diff --git a/runtime/sema/type.go b/runtime/sema/type.go
@@ -6644,18 +6644,21 @@ func (t *CapabilityType) Unify(
 	report func(err error),
 	outerRange ast.Range,
 ) bool {
-	otherOptional, ok := other.(*CapabilityType)
+	otherCap, ok := other.(*CapabilityType)
 	if !ok {
 		return false
 	}
 
-	return t.BorrowType.Unify(otherOptional.BorrowType, typeParameters, report, outerRange)
+	if t.BorrowType == nil {
+		return false
+	}
+
+	return t.BorrowType.Unify(otherCap.BorrowType, typeParameters, report, outerRange)
 }
 
 func (t *CapabilityType) Resolve(typeParameters map[*TypeParameter]Type) Type {
 	var resolvedBorrowType Type
 	if t.BorrowType != nil {
-
 		resolvedBorrowType = t.BorrowType.Resolve(typeParameters)
 	}
 
@@ -6694,7 +6697,9 @@ func (t *CapabilityType) BaseType() Type {
 func (t *CapabilityType) TypeArguments() []Type {
 	borrowType := t.BorrowType
 	if borrowType == nil {
-		borrowType = &AnyType{}
+		borrowType = &ReferenceType{
+			Type: &AnyType{},
+		}
 	}
 	return []Type{
 		borrowType,

diff --git a/runtime/tests/checker/genericfunction_test.go b/runtime/tests/checker/genericfunction_test.go
@@ -886,3 +886,16 @@ func TestCheckGenericFunctionIsInvalid(t *testing.T) {
 
 	assert.False(t, genericFunctionType.IsInvalidType())
 }
+
+// https://github.com/onflow/cadence/issues/225
+func TestCheckBorrowOfCapabilityWithoutTypeArgument(t *testing.T) {
+
+	t.Parallel()
+
+	_, err := ParseAndCheckWithPanic(t, `
+      let cap: Capability = panic("")
+      let ref = cap.borrow<&Int>()!
+    `)
+
+	require.NoError(t, err)
+}