From ffd32dfe8a5d9ca89554552d11cb9fa0f3904bff Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Saugat=20Pachhai=20=28=E0=A4=B8=E0=A5=8C=E0=A4=97=E0=A4=BE?=
 =?UTF-8?q?=E0=A4=A4=29?= <suagatchhetri@outlook.com>
Date: Mon, 6 Oct 2025 20:38:53 +0545
Subject: [PATCH] completion: support fish completion

Fixes #10879.
Upstream PR: https://github.com/iterative/shtab/pull/195.
---
 dvc/cli/completion.py      | 81 +++++++++++++++++++++++++++++++++++---
 dvc/commands/completion.py |  2 +-
 pyproject.toml             |  3 +-
 3 files changed, 78 insertions(+), 8 deletions(-)

diff --git a/dvc/cli/completion.py b/dvc/cli/completion.py
index b257bc20b..36568f13b 100644
--- a/dvc/cli/completion.py
+++ b/dvc/cli/completion.py
@@ -74,22 +74,72 @@ _dvc_compadd_config_vars() {
 }
 """
 
+FISH_PREAMBLE = """
+function __fish_complete_dvc_files
+    __fish_complete_path | string match -re '\\*?.dvc|Dvcfile|dvc\\.yaml'
+end
+
+function __fish_complete_dvc_stages
+    for line in (dvc stage list -q)
+        set -l parts (string split -m1 ' ' -- $line)
+        set -l name $parts[1]
+        set -l desc (string trim $parts[2])
+        echo -e "$name	$desc"
+    end
+end
+
+function __fish_complete_dvc_stages_and_files
+    __fish_complete_dvc_stages
+    __fish_complete_dvc_files
+end
+
+function __fish_complete_dvc_experiments
+    dvc exp list -q --all-commits --names-only
+end
+
+function __fish_complete_dvc_remotes
+    dvc remote list | cut -d' ' -f1
+end
+"""
+
 PREAMBLE = {
     "bash": BASH_PREAMBLE,
     "zsh": ZSH_PREAMBLE,
+    "fish": FISH_PREAMBLE,
 }
 
 FILE = shtab.FILE
 DIR = shtab.DIRECTORY
-DVC_FILE = {"bash": "_dvc_compgen_DVCFiles", "zsh": "_dvc_compadd_DVCFiles"}
-STAGE = {"bash": "_dvc_compgen_stages", "zsh": "_dvc_compadd_stages"}
+DVC_FILE = {
+    "bash": "_dvc_compgen_DVCFiles",
+    "zsh": "_dvc_compadd_DVCFiles",
+    "fish": "__fish_complete_dvc_files",
+}
+STAGE = {
+    "bash": "_dvc_compgen_stages",
+    "zsh": "_dvc_compadd_stages",
+    "fish": "__fish_complete_dvc_stages",
+}
 DVCFILES_AND_STAGE = {
     "bash": "_dvc_compgen_stages_and_files",
     "zsh": "_dvc_compadd_stages_and_files",
+    "fish": "__fish_complete_dvc_stages_and_files",
+}
+EXPERIMENT = {
+    "bash": "_dvc_compgen_exps",
+    "zsh": "_dvc_compadd_exps",
+    "fish": "__fish_complete_dvc_experiments",
+}
+REMOTE = {
+    "bash": "_dvc_compgen_remotes",
+    "zsh": "_dvc_compadd_remotes",
+    "fish": "__fish_complete_dvc_remotes",
+}
+CONFIG_VARS = {
+    "bash": "_dvc_compgen_config_vars",
+    "zsh": "_dvc_compadd_config_vars",
+    "fish": "__fish_complete_dvc_config_vars",
 }
-EXPERIMENT = {"bash": "_dvc_compgen_exps", "zsh": "_dvc_compadd_exps"}
-REMOTE = {"bash": "_dvc_compgen_remotes", "zsh": "_dvc_compadd_remotes"}
-CONFIG_VARS = {"bash": "_dvc_compgen_config_vars", "zsh": "_dvc_compadd_config_vars"}
 
 
 def get_preamble() -> dict[str, str]:
@@ -103,7 +153,26 @@ def get_preamble() -> dict[str, str]:
 _dvc_config_vars=(
     {nl.join(config_vars)}
 )
+"""
+    indent = "\t\t".expandtabs(4)  # 8 spaces
+    lines = (
+        "\n".join(
+            f"{indent}{c} \\"
+            for c in config_vars[:-1]  # all but last
+        )
+        + "\n"
+        + f"{indent}{config_vars[-1]}"
+    )  # last line without backslash
+    config_vars_arr_fish = f"""
+function __fish_complete_dvc_config_vars
+    set -l _dvc_config_vars \\
+{lines}
+    printf %s\\n $_dvc_config_vars
+end
 """
     for shell, preamble in PREAMBLE.items():
-        ret[shell] = config_vars_arr + preamble
+        if shell != "fish":
+            ret[shell] = config_vars_arr + preamble
+        else:
+            ret[shell] = config_vars_arr_fish + preamble
     return ret
diff --git a/dvc/commands/completion.py b/dvc/commands/completion.py
index ca492df39..0efec6137 100644
--- a/dvc/commands/completion.py
+++ b/dvc/commands/completion.py
@@ -8,7 +8,7 @@ from dvc.ui import ui
 logger = logger.getChild(__name__)
 
 
-SUPPORTED_SHELLS = ["bash", "zsh"]
+SUPPORTED_SHELLS = ["bash", "zsh", "fish"]
 
 
 class CmdCompletion(CmdBaseNoRepo):
diff --git a/pyproject.toml b/pyproject.toml
index 48454abd8..03a017ebf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -69,7 +69,8 @@ dependencies = [
     "ruamel.yaml>=0.17.11",
     "scmrepo>=3.5.2,<4",
     "shortuuid>=0.5",
-    "shtab<2,>=1.3.4",
+    # "shtab<2,>=1.3.4",
+    "shtab @ git+https://github.com/skshetry/shtab.git@fish-shell-v2",
     "tabulate>=0.8.7",
     "tomlkit>=0.11.1",
     "tqdm<5,>=4.63.1",