fix: Explicitly tell user when then should use a config file template

internal/chezmoi/sourcestate.go

@@ -321,6 +321,7 @@ type AddOptions struct {
 	Filter            *EntryTypeFilter // Entry type filter.
 	OnIgnoreFunc      func(RelPath)    // Function to call when a target is ignored.
 	PreAddFunc        PreAddFunc       // Function to be called before a source entry is added.
+	ConfigFileAbsPath AbsPath          // Path to config file.
 	ProtectedAbsPaths []AbsPath        // Paths that must not be added.
 	RemoveDir         RelPath          // Directory to remove before adding.
 	ReplaceFunc       ReplaceFunc      // Function to be called before a source entry is replaced.
@@ -360,12 +361,18 @@ func (s *SourceState) Add(
 	destAbsPaths = destAbsPaths[:n]
 
 	// Check for protected paths.
+	for _, destAbsPath := range destAbsPaths {
+		if destAbsPath == options.ConfigFileAbsPath {
+			format := "%s: cannot add chezmoi's config file to chezmoi, use a config file template instead"
+			return fmt.Errorf(format, destAbsPath)
+		}
+	}
 	for _, destAbsPath := range destAbsPaths {
 		for _, protectedAbsPath := range options.ProtectedAbsPaths {
-			if protectedAbsPath.Empty() {
-				continue
-			}
-			if strings.HasPrefix(destAbsPath.String(), protectedAbsPath.String()) {
+			switch {
+			case protectedAbsPath.Empty():
+				// Do nothing.
+			case strings.HasPrefix(destAbsPath.String(), protectedAbsPath.String()):
 				format := "%s: cannot add chezmoi file to chezmoi (%s is protected)"
 				return fmt.Errorf(format, destAbsPath, protectedAbsPath)
 			}

internal/cmd/addcmd.go

@@ -182,18 +182,19 @@ func (c *Config) runAddCmd(cmd *cobra.Command, args []string, sourceState *chezm
 		c.destSystem,
 		destAbsPathInfos,
 		&chezmoi.AddOptions{
-			AutoTemplate:    c.Add.autoTemplate,
-			Create:          c.Add.create,
-			Encrypt:         c.Add.Encrypt,
-			EncryptedSuffix: c.encryption.EncryptedSuffix(),
-			Exact:           c.Add.exact,
-			Filter:          c.Add.filter,
-			OnIgnoreFunc:    c.defaultOnIgnoreFunc,
-			PreAddFunc:      c.defaultPreAddFunc,
+			AutoTemplate:      c.Add.autoTemplate,
+			Create:            c.Add.create,
+			Encrypt:           c.Add.Encrypt,
+			EncryptedSuffix:   c.encryption.EncryptedSuffix(),
+			Exact:             c.Add.exact,
+			Filter:            c.Add.filter,
+			OnIgnoreFunc:      c.defaultOnIgnoreFunc,
+			PreAddFunc:        c.defaultPreAddFunc,
+			ConfigFileAbsPath: c.getConfigFileAbsPath(),
 			ProtectedAbsPaths: []chezmoi.AbsPath{
 				c.CacheDirAbsPath,
 				c.WorkingTreeAbsPath,
-				c.getConfigFileAbsPath(),
+				c.getConfigFileAbsPath().Dir(),
 				persistentStateFileAbsPath,
 				c.sourceDirAbsPath,
 			},

internal/cmd/testdata/scripts/issue2820.txtar

@@ -2,8 +2,12 @@
 ! exec chezmoi add $CHEZMOISOURCEDIR
 stderr 'cannot add chezmoi file to chezmoi'
 
-# test that chezmoi add refuses to add files in chezmoi's config directory
-! exec chezmoi add $CHEZMOICONFIGDIR
+# test that chezmoi add refuses to add chezmoi's config file
+! exec chezmoi add $CHEZMOICONFIGDIR/chezmoi.toml
+stderr 'cannot add chezmoi\x27s config file to chezmoi'
+
+# test that chezmoi add refuses to add files in chezmoi's cache directory
+! exec chezmoi add $HOME/.cache/chezmoi
 stderr 'cannot add chezmoi file to chezmoi'
 
 # test that chezmoi add refuses to add files in chezmoi's source directory when already in that directory
@@ -12,6 +16,7 @@ exists dot_file
 ! exec chezmoi add dot_file
 stderr 'cannot add chezmoi file to chezmoi'
 
+-- home/user/.cache/chezmoi/.keep --
 -- home/user/.config/chezmoi/chezmoi.toml --
 -- home/user/.local/share/chezmoi/dot_file --
 # contents of .file