1 files changed, 5 insertions, 0 deletions

diff --git a/vendor/github.com/zclconf/go-cty/cty/function/stdlib/format.go b/vendor/github.com/zclconf/go-cty/cty/function/stdlib/format.go
index fb24f20..664790b 100644
--- a/vendor/github.com/zclconf/go-cty/cty/function/stdlib/format.go
+++ b/vendor/github.com/zclconf/go-cty/cty/function/stdlib/format.go
@@ -84,6 +84,11 @@ var FormatListFunc = function.New(&function.Spec{
                         argTy := arg.Type()
                         switch {
                         case (argTy.IsListType() || argTy.IsSetType() || argTy.IsTupleType()) && !arg.IsNull():
+                                if !argTy.IsTupleType() && !arg.IsKnown() {
+                                        // We can't iterate this one at all yet then, so we can't
+                                        // yet produce a result.
+                                        return cty.UnknownVal(retType), nil
+                                }
                                 thisLen := arg.LengthInt()
                                 if iterLen == -1 {
                                         iterLen = thisLen