fix: show flags that shadow parent persistent flag in child help (#1776)

This fixes a bug where a child flag that shadows (has the same
name as) a parent persistent flag would not be shown in the
child command's help output and the parent flag would be shown
instead under the global flags section.

This change makes the help output consistent with the
observed behavior during execution, where the child flag is
the one that is actually used.

command.go

@@ -1505,7 +1505,8 @@ func (c *Command) LocalFlags() *flag.FlagSet {
 	}
 
 	addToLocal := func(f *flag.Flag) {
-		if c.lflags.Lookup(f.Name) == nil && c.parentsPflags.Lookup(f.Name) == nil {
+		// Add the flag if it is not a parent PFlag, or it shadows a parent PFlag
+		if c.lflags.Lookup(f.Name) == nil && f != c.parentsPflags.Lookup(f.Name) {
 			c.lflags.AddFlag(f)
 		}
 	}

command_test.go

@@ -707,10 +707,7 @@ func TestEmptyInputs(t *testing.T) {
 	}
 }
 
-func TestOverwrittenFlag(t *testing.T) {
+func TestChildFlagShadowsParentPersistentFlag(t *testing.T) {
-	// TODO: This test fails, but should work.
-	t.Skip()
-
 	parent := &Command{Use: "parent", Run: emptyRun}
 	child := &Command{Use: "child", Run: emptyRun}
 
@@ -732,7 +729,7 @@ func TestOverwrittenFlag(t *testing.T) {
 	}
 
 	if childInherited.Lookup("intf") != nil {
-		t.Errorf(`InheritedFlags should not contain overwritten flag "intf"`)
+		t.Errorf(`InheritedFlags should not contain shadowed flag "intf"`)
 	}
 	if childLocal.Lookup("intf") == nil {
 		t.Error(`LocalFlags expected to contain "intf", got "nil"`)
@@ -887,6 +884,38 @@ func TestHelpCommandExecutedOnChild(t *testing.T) {
 	checkStringContains(t, output, childCmd.Long)
 }
 
+func TestHelpCommandExecutedOnChildWithFlagThatShadowsParentFlag(t *testing.T) {
+	parent := &Command{Use: "parent", Run: emptyRun}
+	child := &Command{Use: "child", Run: emptyRun}
+	parent.AddCommand(child)
+
+	parent.PersistentFlags().Bool("foo", false, "parent foo usage")
+	parent.PersistentFlags().Bool("bar", false, "parent bar usage")
+	child.Flags().Bool("foo", false, "child foo usage") // This shadows parent's foo flag
+	child.Flags().Bool("baz", false, "child baz usage")
+
+	got, err := executeCommand(parent, "help", "child")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	expected := `Usage:
+  parent child [flags]
+
+Flags:
+      --baz    child baz usage
+      --foo    child foo usage
+  -h, --help   help for child
+
+Global Flags:
+      --bar   parent bar usage
+`
+
+	if got != expected {
+		t.Errorf("Help text mismatch.\nExpected:\n%s\n\nGot:\n%s\n", expected, got)
+	}
+}
+
 func TestSetHelpCommand(t *testing.T) {
 	c := &Command{Use: "c", Run: emptyRun}
 	c.AddCommand(&Command{Use: "empty", Run: emptyRun})