terraform: Precondition and postcondition blocks generate dependencies

If a resource or output value has a precondition or postcondition rule
then anything the condition depends on is a dependency of the object,
because the condition rules will be evaluated as part of visiting the
relevant graph node.

internal/terraform/node_output.go

@@ -237,8 +237,11 @@ func referencesForOutput(c *configs.Output) []*addrs.Reference {
 	refs := make([]*addrs.Reference, 0, l)
 	refs = append(refs, impRefs...)
 	refs = append(refs, expRefs...)
+	for _, check := range c.Preconditions {
+		checkRefs, _ := lang.ReferencesInExpr(check.Condition)
+		refs = append(refs, checkRefs...)
+	}
 	return refs
-
 }
 
 // GraphNodeReferencer

internal/terraform/node_resource_abstract.go

@@ -172,6 +172,16 @@ func (n *NodeAbstractResource) References() []*addrs.Reference {
 				result = append(result, refs...)
 			}
 		}
+
+		for _, check := range c.Preconditions {
+			refs, _ := lang.ReferencesInExpr(check.Condition)
+			result = append(result, refs...)
+		}
+		for _, check := range c.Postconditions {
+			refs, _ := lang.ReferencesInExpr(check.Condition)
+			result = append(result, refs...)
+		}
+
 		return result
 	}