12 Commits (4cffff24b1d1e0af43aed445e411f4e9cc6e6238)

Author	SHA1	Message	Date
James Bardin	f46cf7b8bc	cleanup some move graph handling ... Create a separate `validateMoveStatementGraph` function so that `ValidateMoves` and `ApplyMoves` both check the same conditions. Since we're not using the builtin `graph.Validate` method, because we may have multiple roots and want better cycle diagnostics, we need to add checks for self references too. While multiple roots are an error enforced by `Validate` for the concurrent walk, they are OK when using `TransitiveReduction` and `ReverseDepthFirstWalk`, so we can skip that check. Apply moves must first use `TransitiveReduction` to reduce the graph, otherwise nodes may be skipped if they are passed over by a transitive edge.	4 years ago
James Bardin	22dc685052	check for nested module index changes ... Changing only the index on a nested module will cause all nested moves to create cycles, since their full addresses will match both the From and To addresses. When building the dependency graph, check if the parent is only changing the index of the containing module, and prevent the backwards edge for the move.	4 years ago
Alisdair McDiarmid	d7ef123c12	refactoring: Move nested modules ... When applying module `moved` statements by iterating through modules in state, we previously required an exact match from the `moved` statement's `from` field and the module address. This permitted moving resources directly inside a module, but did not recur into module calls within those moved modules. This commit moves that exact match requirement so that it only applies to `moved` statements targeting resources. In turn this allows nested modules to be moved.	4 years ago
James Bardin	cac1f5c264	refactoring: exhaustive NestedWithin checks ... When checking dependencies between statements, we need to check all combinations of To and From addresses.	5 years ago
Martin Atkins	83f0376673	refactoring: ApplyMoves new return type ... When we originally stubbed ApplyMoves we didn't know yet how exactly we'd be using the result, so we made it a double-indexed map allowing looking up moves in both directions. However, in practice we only actually need to look up old addresses by new addresses, and so this commit first removes the double indexing so that each move is only represented by one element in the map. We also need to describe situations where a move was blocked, because in a future commit we'll generate some warnings in those cases. Therefore ApplyMoves now returns a MoveResults object which contains both a map of changes and a map of blocks. The map of blocks isn't used yet as of this commit, but we'll use it in a later commit to produce warnings within the "terraform" package.	5 years ago
Martin Atkins	ee9e346039	refactoring: ApplyMoves skips moving when destination address occupied ... Per our rule that the content of the state can never make a move statement invalid, our behavior for two objects trying to occupy the same address will be to just ignore that and let the object already at the address take priority. For the moment this is silent from an end-user perspective and appears only in our internal logs. However, I'm hoping that our future planned adjustment to the interface of this function will include some way to allow reporting these collisions in some end-user-visible way, either as a separate warning per collision or as a single warning that collects together all of the collisions into a single message somehow. This situation can arise both because the previous run state already contained an object at the target address of a move and because more than one move ends up trying to target the same location. In the latter case, which one "wins" is decided by our depth-first traversal order, which is in turn derived from our chaining and nesting rules and is therefore arbitrary but deterministic.	5 years ago
Martin Atkins	4faac6ee43	core: Record move result information in the plan ... Here we wire through the "move results" into the graph walk data structures so that all of the the nodes which produce plans.ResourceInstanceChange values can capture the "PrevRunAddr" for each resource instance. This doesn't actually quite work yet, because the logic in Context.Plan isn't actually correct and so the updated state from refactoring.ApplyMoves isn't actually visible as the "previous run state". For that reason, the context test in this commit is currently skipped, with the intent of re-enabling it once the updated state is properly propagating into the plan graph walk and thus we can actually react to the result of the move while choosing actions for those addresses.	5 years ago
James Bardin	493ec4e6c5	correct the direction and walk order of the graph	5 years ago
James Bardin	6401022bc8	don't take the address of a range variable	5 years ago
James Bardin	09ab952683	fix ApplyMoves tests ... Add empty result value, since ApplyMoves does not return nil. Fix the desired addresses for moves.	5 years ago
Martin Atkins	3e5bfa7364	refactoring: Stubbing of the logic for handling moves ... This is a whole lot of nothing right now, just stubbing out some control flow that ultimately just leads to TODOs that cause it to do nothing at all. My intent here is to get this cross-cutting skeleton in place and thus make it easier for us to collaborate on adding the meat to it, so that it's more likely we can work on different parts separately and still get a result that tessellates.	5 years ago
Martin Atkins	22eee529e3	addrs: MoveEndpointInModule ... We previously built out addrs.UnifyMoveEndpoints with a different implementation strategy in mind, but that design turns out to not be viable because it forces us to move to AbsMoveable addresses too soon, before we've done the analysis required to identify chained and nested moves. Instead, UnifyMoveEndpoints will return a new type MoveEndpointInModule which conceptually represents a matching pattern which either matches or doesn't match a particular AbsMoveable. It does this by just binding the unified relative address from the MoveEndpoint to the module where it was declared, and thus allows us to distinguish between the part of the module path which applies to any instances of the given modules vs. the user-specified part which must identify particular module instances.	5 years ago