Evaluate ModuleCallArguments using the appropriate ModuleInstance scope

terraform/eval_context_builtin.go

@@ -34,7 +34,7 @@ type BuiltinEvalContext struct {
 
 	// pathSet indicates that this context was explicitly created for a
 	// specific path, and can be safely used for evaluation. This lets us
-	// differentiate between Pathvalue being unset, and the zero value which is
+	// differentiate between PathValue being unset, and the zero value which is
 	// equivalent to RootModuleInstance.  Path and Evaluation methods will
 	// panic if this is not set.
 	pathSet bool

terraform/eval_variable.go

@@ -40,6 +40,7 @@ type EvalModuleCallArgument struct {
 	Addr           addrs.InputVariable
 	Config         *configs.Variable
 	Expr           hcl.Expression
+	ModuleInstance addrs.ModuleInstance
 
 	// If this flag is set, any diagnostics are discarded and this operation
 	// will always succeed, though may produce an unknown value in the
@@ -68,7 +69,11 @@ func (n *EvalModuleCallArgument) Eval(ctx EvalContext) (interface{}, error) {
 		return nil, nil
 	}
 
-	val, diags := ctx.EvaluateExpr(expr, cty.DynamicPseudoType, nil)
+	// Get the repetition data for this module instance,
+	// so we can create the appropriate scope for evaluating our expression
+	moduleInstanceRepetitionData := ctx.InstanceExpander().GetModuleInstanceRepetitionData(n.ModuleInstance)
+	scope := ctx.EvaluationScope(nil, moduleInstanceRepetitionData)
+	val, diags := scope.EvalExpr(expr, cty.DynamicPseudoType)
 
 	// We intentionally passed DynamicPseudoType to EvaluateExpr above because
 	// now we can do our own local type conversion and produce an error message

terraform/node_module_variable.go

@@ -41,6 +41,7 @@ func (n *NodePlannableModuleVariable) DynamicExpand(ctx EvalContext) (*Graph, er
 			Addr:           n.Addr.Absolute(module),
 			Config:         n.Config,
 			Expr:           n.Expr,
+			ModuleInstance: module,
 		}
 		g.Add(o)
 	}
@@ -114,6 +115,9 @@ type NodeApplyableModuleVariable struct {
 	Addr   addrs.AbsInputVariableInstance
 	Config *configs.Variable // Config is the var in the config
 	Expr   hcl.Expression    // Expr is the value expression given in the call
+	// ModuleInstance in order to create the appropriate context for evaluating
+	// ModuleCallArguments, ex. so count.index and each.key can resolve
+	ModuleInstance addrs.ModuleInstance
 }
 
 // Ensure that we are implementing all of the interfaces we think we are
@@ -220,11 +224,12 @@ func (n *NodeApplyableModuleVariable) EvalTree() EvalNode {
 		Nodes: []EvalNode{
 			&EvalOpFilter{
 				Ops: []walkOperation{walkRefresh, walkPlan, walkApply,
-					walkDestroy, walkValidate},
+					walkDestroy},
 				Node: &EvalModuleCallArgument{
 					Addr:           n.Addr.Variable,
 					Config:         n.Config,
 					Expr:           n.Expr,
+					ModuleInstance: n.ModuleInstance,
 					Values:         vals,
 
 					IgnoreDiagnostics: false,

terraform/testdata/plan-modules-expand/main.tf

@@ -10,10 +10,9 @@ variable "myvar" {
   default = "baz"
 }
 
-
 module "count_child" {
   count = local.val
-  foo = 2
+  foo = count.index
   bar = var.myvar
   source = "./child"
 }