perf: Improve merger.Mergefile

merger/merger.go

@@ -117,7 +117,7 @@ func MergeFile(oldFile *rule.File, emptyRules, genRules []*rule.Rule, phase Phas
 
 	// Merge empty rules into the file and delete any rules which become empty.
 	for _, emptyRule := range emptyRules {
-		if oldRule, _ := Match(oldFile.Rules, emptyRule, kinds[emptyRule.Kind()]); oldRule != nil {
+		if oldRule, _ := match(oldFile.Rules, emptyRule, kinds[emptyRule.Kind()], false); oldRule != nil {
 			if oldRule.ShouldKeep() {
 				continue
 			}
@@ -211,6 +211,10 @@ func substituteRule(r *rule.Rule, substitutions map[string]string, info rule.Kin
 // order that attributes are listed). If disambiguation is successful,
 // the rule and nil are returned. Otherwise, nil and an error are returned.
 func Match(rules []*rule.Rule, x *rule.Rule, info rule.KindInfo) (*rule.Rule, error) {
+	return match(rules, x, info, true)
+}
+
+func match(rules []*rule.Rule, x *rule.Rule, info rule.KindInfo, wantError bool) (*rule.Rule, error) {
 	xname := x.Name()
 	xkind := x.Kind()
 	var nameMatches []*rule.Rule
@@ -227,11 +231,17 @@ func Match(rules []*rule.Rule, x *rule.Rule, info rule.KindInfo) (*rule.Rule, er
 	if len(nameMatches) == 1 {
 		y := nameMatches[0]
 		if xkind != y.Kind() {
+			if !wantError {
+				return nil, nil
+			}
 			return nil, fmt.Errorf("could not merge %s(%s): a rule of the same name has kind %s", xkind, xname, y.Kind())
 		}
 		return y, nil
 	}
 	if len(nameMatches) > 1 {
+		if !wantError {
+			return nil, nil
+		}
 		return nil, fmt.Errorf("could not merge %s(%s): multiple rules have the same name", xkind, xname)
 	}
 
@@ -245,6 +255,9 @@ func Match(rules []*rule.Rule, x *rule.Rule, info rule.KindInfo) (*rule.Rule, er
 		if len(attrMatches) == 1 {
 			return attrMatches[0], nil
 		} else if len(attrMatches) > 1 {
+			if !wantError {
+				return nil, nil
+			}
 			return nil, fmt.Errorf("could not merge %s(%s): multiple rules have the same attribute %s", xkind, xname, key)
 		}
 	}
@@ -253,6 +266,9 @@ func Match(rules []*rule.Rule, x *rule.Rule, info rule.KindInfo) (*rule.Rule, er
 		if len(kindMatches) == 1 {
 			return kindMatches[0], nil
 		} else if len(kindMatches) > 1 {
+			if !wantError {
+				return nil, nil
+			}
 			return nil, fmt.Errorf("could not merge %s(%s): multiple rules have the same kind but different names", xkind, xname)
 		}
 	}

rule/rule.go

@@ -725,7 +725,7 @@ func (l *Load) sync() {
 // Rule represents a rule statement within a build file.
 type Rule struct {
 	stmt
-	kind        bzl.Expr
+	kind        string
 	args        []bzl.Expr
 	attrs       map[string]attrValue
 	private     map[string]interface{}
@@ -748,7 +748,7 @@ func NewRule(kind, name string) *Rule {
 
 	r := &Rule{
 		stmt:        stmt{expr: call},
-		kind:        kindIdent,
+		kind:        kind,
 		attrs:       map[string]attrValue{},
 		private:     map[string]interface{}{},
 		sortedAttrs: []string{"deps", "srcs"},
@@ -850,7 +850,7 @@ func ruleFromExpr(index int, expr bzl.Expr) *Rule {
 			expr:     call,
 			comments: commentsFromExpr(expr),
 		},
-		kind:    kind,
+		kind:    bzl.FormatString(kind),
 		args:    args,
 		attrs:   attrs,
 		private: map[string]interface{}{},
@@ -866,12 +866,12 @@ func (r *Rule) ShouldKeep() bool {
 
 // Kind returns the kind of rule this is (for example, "go_library").
 func (r *Rule) Kind() string {
-	return bzl.FormatString(r.kind)
+	return r.kind
 }
 
 // SetKind changes the kind of rule this is.
 func (r *Rule) SetKind(kind string) {
-	r.kind = &bzl.Ident{Name: kind}
+	r.kind = kind
 	r.updated = true
 }