[lvgl] Keep LV_CONF_PATH one argument when the build path has a space (#20758)

esphome/components/lvgl/__init__.py

@@ -335,6 +335,16 @@ def final_validation(config_list):
                 widget_type.final_validate(name, conf, widget_conf, path[1:])
 
 
+def lv_conf_path_flag(lv_conf_h_file: Path) -> str:
+    """The ``-DLV_CONF_PATH`` build flag, decoded identically by the shell
+    lexers (PlatformIO, host, ESP8266) and the quoted CMake arguments
+    (ESP-IDF, Zephyr) the build flags pass through."""
+    # forward slashes for Windows, then escape what shlex or a quoted CMake
+    # argument would not pass through literally
+    path = re.sub(r"[^\w/.:+=,-]", r"\\\g<0>", Path(lv_conf_h_file).as_posix())
+    return f'-DLV_CONF_PATH=\\"{path}\\"'
+
+
 async def to_code(configs):
     config_0 = configs[0]
     # Global configuration
@@ -563,9 +573,7 @@ async def to_code(configs):
     if write_file_if_changed(lv_conf_h_file, generate_lv_conf_h()):
         clean_build(clear_pio_cache=False)
     cg.add_build_flag("-DLV_CONF_H=1")
-    # handle windows paths in a way that doesn't break the generated C++
-    lv_conf_h_path = Path(lv_conf_h_file).as_posix()
-    cg.add_build_flag(f'-DLV_CONF_PATH=\\"{lv_conf_h_path}\\"')
+    cg.add_build_flag(lv_conf_path_flag(lv_conf_h_file))
     cg.add_build_flag("-DLV_KCONFIG_IGNORE")
 
     for prop in df.get_remapped_uses():

tests/component_tests/lvgl/test_lv_conf_path_flag.py

@@ -0,0 +1,39 @@
+"""The ``-DLV_CONF_PATH`` build flag carries a path. PlatformIO, the host
+build and the native ESP8266 build shell-lex build flags, while the ESP-IDF
+and Zephyr builds write each flag into a quoted CMake argument; both must
+decode it to one ``-DLV_CONF_PATH="..."`` argument, including when the
+project path contains a space."""
+
+from __future__ import annotations
+
+from pathlib import Path
+import re
+import shlex
+
+import pytest
+
+from esphome.components.lvgl import lv_conf_path_flag
+
+
+def _cmake_quoted_argument(flag: str) -> str:
+    """Decode ``flag`` as CMake decodes a quoted argument: a backslash escapes the next character."""
+    return re.sub(r"\\(.)", r"\1", flag)
+
+
+@pytest.mark.parametrize(
+    "build_path",
+    [
+        "/home/user/.esphome/build/node",
+        "/Users/me/with space/.esphome/build/node",
+        "/srv/odd 'quote' $(and)/build",
+        "C:/Users/Kris Maddens/esphome/.esphome/build/node",
+    ],
+    ids=["plain", "space", "shell-specials", "windows"],
+)
+def test_flag_is_one_argument_everywhere(build_path: str) -> None:
+    lv_conf_h_file = Path(build_path) / "src" / "lv_conf.h"
+    flag = lv_conf_path_flag(lv_conf_h_file)
+    expected = f'-DLV_CONF_PATH="{lv_conf_h_file.as_posix()}"'
+
+    assert shlex.split(flag) == [expected]
+    assert _cmake_quoted_argument(flag) == expected