From 83a5a308b1b170cdba74d7b96a9a207d882278ac Mon Sep 17 00:00:00 2001
From: "Lukacs T. Berki" <lberki@google.com>
Date: Tue, 19 Apr 2022 18:12:03 +0200
Subject: [PATCH] Remove the concept of "early mutator".

It was unused and as such, maintenance cost for no benefit.

Test: Presubmits.
Change-Id: Ifc35c0f55647ef88ed0bfa44bcf709e51a904ea4
---
 context.go    | 40 +---------------------------------------
 module_ctx.go | 27 ---------------------------
 2 files changed, 1 insertion(+), 66 deletions(-)

diff --git a/context.go b/context.go
index e7b0d7d..6496948 100644
--- a/context.go
+++ b/context.go
@@ -83,7 +83,6 @@ type Context struct {
 	preSingletonInfo    []*singletonInfo
 	singletonInfo       []*singletonInfo
 	mutatorInfo         []*mutatorInfo
-	earlyMutatorInfo    []*mutatorInfo
 	variantMutatorNames []string
 
 	depsModified uint32 // positive if a mutator modified the dependencies
@@ -630,38 +629,6 @@ func (mutator *mutatorInfo) Parallel() MutatorHandle {
 	return mutator
 }
 
-// RegisterEarlyMutator registers a mutator that will be invoked to split
-// Modules into multiple variant Modules before any dependencies have been
-// created.  Each registered mutator is invoked in registration order once
-// per Module (including each variant from previous early mutators).  Module
-// order is unpredictable.
-//
-// In order for dependencies to be satisifed in a later pass, all dependencies
-// of a module either must have an identical variant or must have no variations.
-//
-// The mutator type names given here must be unique to all bottom up or early
-// mutators in the Context.
-//
-// Deprecated, use a BottomUpMutator instead.  The only difference between
-// EarlyMutator and BottomUpMutator is that EarlyMutator runs before the
-// deprecated DynamicDependencies.
-func (c *Context) RegisterEarlyMutator(name string, mutator EarlyMutator) {
-	for _, m := range c.variantMutatorNames {
-		if m == name {
-			panic(fmt.Errorf("mutator name %s is already registered", name))
-		}
-	}
-
-	c.earlyMutatorInfo = append(c.earlyMutatorInfo, &mutatorInfo{
-		bottomUpMutator: func(mctx BottomUpMutatorContext) {
-			mutator(mctx)
-		},
-		name: name,
-	})
-
-	c.variantMutatorNames = append(c.variantMutatorNames, name)
-}
-
 // SetIgnoreUnknownModuleTypes sets the behavior of the context in the case
 // where it encounters an unknown module type while parsing Blueprints files. By
 // default, the context will report unknown module types as an error.  If this
@@ -2483,13 +2450,8 @@ func (c *Context) PrepareBuildActions(config interface{}) (deps []string, errs [
 }
 
 func (c *Context) runMutators(ctx context.Context, config interface{}) (deps []string, errs []error) {
-	var mutators []*mutatorInfo
-
 	pprof.Do(ctx, pprof.Labels("blueprint", "runMutators"), func(ctx context.Context) {
-		mutators = append(mutators, c.earlyMutatorInfo...)
-		mutators = append(mutators, c.mutatorInfo...)
-
-		for _, mutator := range mutators {
+		for _, mutator := range c.mutatorInfo {
 			pprof.Do(ctx, pprof.Labels("mutator", mutator.name), func(context.Context) {
 				var newDeps []string
 				if mutator.topDownMutator != nil {
diff --git a/module_ctx.go b/module_ctx.go
index 787f483..53ee405 100644
--- a/module_ctx.go
+++ b/module_ctx.go
@@ -831,32 +831,6 @@ type BaseMutatorContext interface {
 	MutatorName() string
 }
 
-type EarlyMutatorContext interface {
-	BaseMutatorContext
-
-	// CreateVariations splits  a module into multiple variants, one for each name in the variationNames
-	// parameter.  It returns a list of new modules in the same order as the variationNames
-	// list.
-	//
-	// If any of the dependencies of the module being operated on were already split
-	// by calling CreateVariations with the same name, the dependency will automatically
-	// be updated to point the matching variant.
-	//
-	// If a module is split, and then a module depending on the first module is not split
-	// when the Mutator is later called on it, the dependency of the depending module will
-	// automatically be updated to point to the first variant.
-	CreateVariations(...string) []Module
-
-	// CreateLocalVariations splits a module into multiple variants, one for each name in the variantNames
-	// parameter.  It returns a list of new modules in the same order as the variantNames
-	// list.
-	//
-	// Local variations do not affect automatic dependency resolution - dependencies added
-	// to the split module via deps or DynamicDependerModule must exactly match a variant
-	// that contains all the non-local variations.
-	CreateLocalVariations(...string) []Module
-}
-
 type TopDownMutatorContext interface {
 	BaseMutatorContext
 
@@ -995,7 +969,6 @@ type BottomUpMutatorContext interface {
 // if a second Mutator chooses to split the module a second time.
 type TopDownMutator func(mctx TopDownMutatorContext)
 type BottomUpMutator func(mctx BottomUpMutatorContext)
-type EarlyMutator func(mctx EarlyMutatorContext)
 
 // DependencyTag is an interface to an arbitrary object that embeds BaseDependencyTag.  It can be
 // used to transfer information on a dependency between the mutator that called AddDependency