[espidf] Skip the lwip sources that compile to empty objects (#20000)

tests/script/test_check_idf_py_equivalence.py

@@ -103,6 +103,7 @@ def _run_check(
         patch.object(framework, "read_idf_version_txt", return_value=versions[0]),
         patch.object(framework, "read_idf_version_header", return_value=versions[1]),
         patch.object(framework, "idf_tools_version", return_value=versions[2]),
+        patch.object(guard, "_lwip_empty_source_problems", return_value=[]),
         patch.object(guard.subprocess, "run", side_effect=run),
         patch.dict(os.environ),
     ):
@@ -319,6 +320,99 @@ def test_main_without_build_trees(
     assert "No native ESP-IDF build tree found" in capsys.readouterr().out
 
 
+def _make_lwip_tree(tmp_path: Path, objects: list[str], config: dict) -> Path:
+    """A tree with lwip objects, their sdkconfig.json and an nm in the cache."""
+    tree = _make_tree(tmp_path)
+    objdir = tree / "build" / "esp-idf" / "lwip" / "CMakeFiles" / "__idf_lwip.dir"
+    for name in objects:
+        (objdir / name).parent.mkdir(parents=True, exist_ok=True)
+        (objdir / name).write_bytes(b"x")
+    (tree / "build" / "config").mkdir(parents=True, exist_ok=True)
+    (tree / "build" / "config" / "sdkconfig.json").write_text(json.dumps(config))
+    with (tree / "build" / "CMakeCache.txt").open("a") as cache:
+        cache.write("CMAKE_NM:FILEPATH=/tools/nm\n")
+    return tree
+
+
+def _run_lwip_check(
+    tree: Path,
+    non_empty: set[str] = frozenset(),
+    failing: set[str] = frozenset(),
+    calls: list[list[str]] | None = None,
+) -> list[str]:
+    """Run the lwip check with nm faked; ``calls`` collects the nm commands."""
+
+    def run(cmd: list[str], **kwargs: object) -> subprocess.CompletedProcess:
+        if calls is not None:
+            calls.append(cmd)
+        name = Path(cmd[-1]).name
+        if name in failing:
+            return subprocess.CompletedProcess(cmd, 1, "", "bad object")
+        return subprocess.CompletedProcess(
+            cmd, 0, "symbol\n" if name in non_empty else "", ""
+        )
+
+    with (
+        patch.object(toolchain, "run_reconfigure", return_value=0) as reconfigure,
+        patch.object(toolchain, "_run_ninja", return_value=0),
+        patch.object(guard.subprocess, "run", side_effect=run),
+    ):
+        problems = guard._lwip_empty_source_problems(tree)
+    reconfigure.assert_called_once_with(
+        extra_env={build_gen.LWIP_FULL_SOURCES_ENV: "1"}
+    )
+    return problems
+
+
+def test_lwip_check_inspects_only_the_dropped_sources(tmp_path: Path) -> None:
+    """An option that is on, or absent (invisible), keeps its sources unchecked."""
+    tree = _make_lwip_tree(
+        tmp_path,
+        [
+            "lwip/src/netif/ppp/auth.c.obj",
+            "lwip/src/core/ipv6/ip6.c.obj",
+            "lwip/src/core/ipv4/autoip.c.obj",
+        ],
+        {"LWIP_PPP_SUPPORT": False, "LWIP_IPV6": True},
+    )
+    calls: list[list[str]] = []
+    assert _run_lwip_check(tree, calls=calls) == []
+    assert [Path(c[-1]).name for c in calls] == ["auth.c.obj"]
+
+
+def test_lwip_check_flags_a_dropped_source_with_symbols(tmp_path: Path) -> None:
+    tree = _make_lwip_tree(
+        tmp_path, ["lwip/src/netif/ppp/auth.c.obj"], {"LWIP_PPP_SUPPORT": False}
+    )
+    assert _run_lwip_check(tree, non_empty={"auth.c.obj"}) == [
+        guard.LWIP_NOT_EMPTY.format(source="auth.c", option="CONFIG_LWIP_PPP_SUPPORT")
+    ]
+
+
+def test_lwip_check_flags_a_failed_nm(tmp_path: Path) -> None:
+    """A broken nm must not pass as an empty object."""
+    tree = _make_lwip_tree(
+        tmp_path, ["lwip/src/netif/ppp/auth.c.obj"], {"LWIP_PPP_SUPPORT": False}
+    )
+    assert _run_lwip_check(tree, failing={"auth.c.obj"}) == [
+        guard.LWIP_NM_FAILED.format(source="auth.c", error="bad object")
+    ]
+
+
+def test_lwip_check_fails_per_pattern_that_matched_nothing(tmp_path: Path) -> None:
+    """A stale pattern is reported even while the others still match."""
+    tree = _make_lwip_tree(
+        tmp_path,
+        ["lwip/src/netif/ppp/auth.c.obj"],
+        {"LWIP_PPP_SUPPORT": False, "LWIP_STATS": False},
+    )
+    assert _run_lwip_check(tree) == [
+        guard.LWIP_NOTHING_MATCHED.format(
+            regex="/core/stats[.]c$", option="CONFIG_LWIP_STATS"
+        )
+    ]
+
+
 @pytest.mark.parametrize(("problems", "rc"), [([], 0), (["idf.py changed x"], 1)])
 def test_main_reports_each_tree(
     tmp_path: Path,

tests/unit_tests/build_gen/test_espidf.py

@@ -222,6 +222,24 @@ def test_get_project_cmakelists_size_command_uses_json2() -> None:
     assert "--format=json2" in content
 
 
+def test_get_project_cmakelists_drops_empty_lwip_sources() -> None:
+    """The filter comes after project(), where the lwip target exists."""
+    from esphome.build_gen.espidf import (
+        LWIP_EMPTY_SOURCES,
+        LWIP_FULL_SOURCES_ENV,
+        lwip_empty_source_gate,
+    )
+
+    content = _render()
+    filter_at = content.index(
+        "set_property(TARGET ${esphome_lwip_lib} PROPERTY SOURCES"
+    )
+    assert filter_at > content.index("project(")
+    assert f"NOT DEFINED ENV{{{LWIP_FULL_SOURCES_ENV}}}" in content
+    for entry in LWIP_EMPTY_SOURCES:
+        assert lwip_empty_source_gate(*entry) in content
+
+
 def test_get_project_cmakelists_declares_map_as_link_byproduct() -> None:
     """The link declares the map so size can build in the same ninja run."""
     content = _render()