Resolve flag aliases in failed command routes

internal/cobra/parse.go

@@ -19,10 +19,11 @@ import (
 
 // Session owns one mutable backend tree for a single command invocation.
 type Session struct {
-	metadata     *commandmeta.Command
-	root         *spfcobra.Command
-	declarations map[*spfcobra.Command]*commandmeta.Command
-	flagAliases  []commandmeta.FlagAlias
+	metadata           *commandmeta.Command
+	root               *spfcobra.Command
+	declarations       map[*spfcobra.Command]*commandmeta.Command
+	flagAliases        []commandmeta.FlagAlias
+	flagAliasesForPath func([]string) []commandmeta.FlagAlias
 }
 
 // Prepare constructs a fresh backend tree for one invocation.
@@ -33,6 +34,7 @@ func Prepare(root *commandmeta.Command, options commandmeta.ParseOptions) *Sessi
 	}
 	session.metadata = root
 	session.flagAliases = append([]commandmeta.FlagAlias(nil), options.FlagAliases...)
+	session.flagAliasesForPath = options.FlagAliasesForPath
 	options = normalizeOptions(options)
 	session.root, session.declarations = buildTree(root, options)
 	return session
@@ -80,7 +82,11 @@ func (session *Session) Parse(argv []string) commandmeta.Result {
 	localFlags := make([]commandmeta.Flag, 0, len(selectedNode.Flags)+len(selectedNode.CoreFlags))
 	localFlags = append(localFlags, selectedNode.Flags...)
 	localFlags = append(localFlags, selectedNode.CoreFlags...)
-	interpreted, spellings, occurrences, interpretationFailure := interpretFlagTokens(remaining, localFlags, session.flagAliases)
+	aliases := session.flagAliases
+	if session.flagAliasesForPath != nil {
+		aliases = session.flagAliasesForPath(result.Path)
+	}
+	interpreted, spellings, occurrences, interpretationFailure := interpretFlagTokens(remaining, localFlags, aliases)
 	for _, flag := range localFlags {
 		if value := selected.Flags().Lookup(flag.Name); value != nil {
 			value.Value.(*rawValue).queueSpellings(spellings[flag.Name])

internal/commandmeta/metadata.go

@@ -130,9 +130,12 @@ type Result struct {
 
 // ParseOptions makes parser context and streams explicit.
 type ParseOptions struct {
-	Context     context.Context
-	In          io.Reader
-	Out         io.Writer
-	Err         io.Writer
-	FlagAliases []FlagAlias
+	// FlagAliasesForPath selects aliases for the actual parser context when
+	// routing has not already selected one. It overrides FlagAliases when set.
+	FlagAliasesForPath func([]string) []FlagAlias
+	Context            context.Context
+	In                 io.Reader
+	Out                io.Writer
+	Err                io.Writer
+	FlagAliases        []FlagAlias
 }