Interpret \t in the indent setting as a tab

docs/configuration/options.md

@@ -524,7 +524,7 @@ forced_separate = ["glob_exp1", "glob_exp2"]
 
 ## Indent
 
-String to place for indents defaults to "    " (4 spaces).
+String to place for indents defaults to "    " (4 spaces). Accepts a number of spaces, `tab` (or `\t`) for a tab, or a literal string. Only used by the hanging indent multi_line_output modes; the grid and vertical modes align wrapped imports with the opening parenthesis instead.
 
 **Type:** String  
 **Default:** `    `  

isort/main.py

@@ -507,7 +507,10 @@ def _build_arg_parser() -> argparse.ArgumentParser:
     output_group.add_argument(
         "-i",
         "--indent",
-        help='String to place for indents defaults to "    " (4 spaces).',
+        help='String to place for indents defaults to "    " (4 spaces). '
+        "Accepts a number of spaces, `tab` (or `\\t`) for a tab, or a literal string. "
+        "Only used by the hanging indent multi_line_output modes; the grid and vertical "
+        "modes align wrapped imports with the opening parenthesis instead.",
         dest="indent",
         type=str,
     )

isort/settings.py

@@ -360,6 +360,8 @@ def __init__(
                 indent = indent.strip("'").strip('"')
                 if indent.lower() == "tab":
                     indent = "\t"
+                else:
+                    indent = indent.replace("\\t", "\t")
             combined_config["indent"] = indent
 
         known_other = {}

tests/unit/test_settings.py

@@ -41,6 +41,26 @@ def test_invalid_profile(self) -> None:
         with pytest.raises(exceptions.ProfileDoesNotExist):
             Config(profile="blackandwhitestylemixedwithpep8")
 
+    @pytest.mark.parametrize(
+        ("indent", "expected"),
+        [
+            ("tab", "\t"),
+            ("Tab", "\t"),
+            ('"tab"', "\t"),
+            ("\t", "\t"),
+            ("\\t", "\t"),
+            ("\\t\\t", "\t\t"),
+            ("2", "  "),
+            ("'  '", "  "),
+        ],
+    )
+    def test_indent(self, indent: str, expected: str) -> None:
+        assert Config(indent=indent).indent == expected
+
+    def test_indent_escaped_tab_in_config_file(self, tmp_path: Path) -> None:
+        (tmp_path / ".isort.cfg").write_text("[settings]\nindent=\\t\n", encoding="utf8")
+        assert Config(settings_path=str(tmp_path)).indent == "\t"
+
     def test_is_skipped(self) -> None:
         assert Config().is_skipped(Path("C:\\path\\isort.py"))
         assert Config(skip=["/path/isort.py"]).is_skipped(Path("C:\\path\\isort.py"))