Modify gorepomod to unpin conditionally.

cmd/gorepomod/README.md

@@ -37,14 +37,19 @@ Use this to get module names for use in other commands.
 Creates a change with mechanical updates
 to `go.mod` and `go.sum` files.
 
-#### `gorepomod unpin {module}`
+#### `gorepomod unpin {module} [{conditionalmodule}]`
 
 Creates a change to `go.mod` files.
 
 For each module _m_ in the repository,
-if _m_ depends on a _{module}_,
-then _m_'s dependency on it will be replaced by
-a relative path to the in-repo module.
+if _m_ depends on a _{module}_, then
+_m_'s dependency on _{module} will be
+replaced by a relative path to the in-repo
+version of _{module}_.
+
+If _conditionalModule_ is specified, then
+the replacement of _{module}_ will happen
+if _m_ depends on _{conditionalModule}_.
 
 #### `gorepomod pin {module} [{version}]`
 

cmd/gorepomod/internal/arguments/args.go

@@ -51,11 +51,12 @@ const (
 )
 
 type Args struct {
-	cmd        Command
-	moduleName misc.ModuleShortName
-	version    semver.SemVer
-	bump       semver.SvBump
-	doIt       bool
+	cmd               Command
+	moduleName        misc.ModuleShortName
+	conditionalModule misc.ModuleShortName
+	version           semver.SemVer
+	bump              semver.SvBump
+	doIt              bool
 }
 
 func (a *Args) GetCommand() Command {
@@ -74,6 +75,10 @@ func (a *Args) ModuleName() misc.ModuleShortName {
 	return a.moduleName
 }
 
+func (a *Args) ConditionalModule() misc.ModuleShortName {
+	return a.conditionalModule
+}
+
 func (a *Args) Exclusions() (result []string) {
 	// Make sure the list has no repeats.
 	for k := range utils.SliceToSet(excSlice) {
@@ -122,6 +127,7 @@ func Parse() (result *Args, err error) {
 	result.doIt = clArgs.doIt
 
 	result.moduleName = misc.ModuleUnknown
+	result.conditionalModule = misc.ModuleUnknown
 	if !clArgs.more() {
 		return nil, fmt.Errorf("command needs at least one arg")
 	}
@@ -146,6 +152,9 @@ func Parse() (result *Args, err error) {
 			return nil, fmt.Errorf("unpin needs a moduleName to unpin")
 		}
 		result.moduleName = misc.ModuleShortName(clArgs.next())
+		if clArgs.more() {
+			result.conditionalModule = misc.ModuleShortName(clArgs.next())
+		}
 		result.cmd = UnPin
 	case cmdTidy:
 		result.cmd = Tidy

cmd/gorepomod/internal/repo/manager.go

@@ -53,10 +53,17 @@ func (mgr *Manager) Pin(
 	})
 }
 
-func (mgr *Manager) UnPin(doIt bool, target misc.LaModule) error {
+func (mgr *Manager) UnPin(
+	doIt bool, target misc.LaModule, conditional misc.LaModule) error {
 	return mgr.modules.Apply(func(m misc.LaModule) error {
-		if yes, oldVersion := m.DependsOn(target); yes {
-			return edit.New(m, doIt).UnPin(target, oldVersion)
+		if conditional == nil {
+			if yes, oldVersion := m.DependsOn(target); yes {
+				return edit.New(m, doIt).UnPin(target, oldVersion)
+			}
+		} else {
+			if yes, oldVersion := m.DependsOn(conditional); yes {
+				return edit.New(m, doIt).UnPin(target, oldVersion)
+			}
 		}
 		return nil
 	})

cmd/gorepomod/main.go

@@ -27,25 +27,34 @@ func loadRepoManager(args *arguments.Args) (*repo.Manager, error) {
 	return pr.NewRepoManager(), nil
 }
 
+func findModule(
+	name misc.ModuleShortName, mgr *repo.Manager) (m misc.LaModule, err error) {
+	if name != misc.ModuleUnknown {
+		m = mgr.FindModule(name)
+		if m == nil {
+			return nil, fmt.Errorf(
+				"cannot find module %q in repo %s", name, mgr.RepoPath())
+		}
+	}
+	return
+}
+
 func actualMain() error {
 	args, err := arguments.Parse()
 	if err != nil {
 		return err
 	}
-
 	mgr, err := loadRepoManager(args)
 	if err != nil {
 		return err
 	}
-
-	var targetModule misc.LaModule = nil
-	if args.ModuleName() != misc.ModuleUnknown {
-		targetModule = mgr.FindModule(args.ModuleName())
-		if targetModule == nil {
-			return fmt.Errorf(
-				"cannot find module %q in repo %s",
-				args.ModuleName(), mgr.RepoPath())
-		}
+	targetModule, err := findModule(args.ModuleName(), mgr)
+	if err != nil {
+		return err
+	}
+	conditionalModule, err := findModule(args.ConditionalModule(), mgr)
+	if err != nil {
+		return err
 	}
 
 	switch args.GetCommand() {
@@ -60,7 +69,7 @@ func actualMain() error {
 		}
 		return mgr.Pin(args.DoIt(), targetModule, v)
 	case arguments.UnPin:
-		return mgr.UnPin(args.DoIt(), targetModule)
+		return mgr.UnPin(args.DoIt(), targetModule, conditionalModule)
 	case arguments.Release:
 		return mgr.Release(targetModule, args.Bump(), args.DoIt())
 	case arguments.UnRelease: