Add the OBJECT_DEPENDS edge so a rebuilt gch recompiles its consumers

esphome/build_gen/espidf.py

@@ -3,6 +3,7 @@
 import hashlib
 import json
 import logging
+import os
 from pathlib import Path
 import subprocess
 
@@ -331,11 +332,16 @@ def _pch_cmake() -> str:
     if not pch_enabled():
         return ""
     return f"""
-# ESPHome precompiled header (see esphome/build_helpers/pch.py)
+# ESPHome precompiled header (see esphome/build_helpers/pch.py). The
+# OBJECT_DEPENDS edge is on the header, not the .gch: headers baked into
+# a .gch drop out of the TU depfiles, and prepare_pch() touches the
+# header whenever it rebuilds the .gch so consumers recompile.
 target_compile_options(${{COMPONENT_LIB}} PRIVATE
     "$<$<COMPILE_LANGUAGE:CXX>:-include>"
     "$<$<COMPILE_LANGUAGE:CXX>:{PCH_HEADER_NAME}>"
 )
+set_source_files_properties(${{app_sources}} PROPERTIES
+    OBJECT_DEPENDS "${{CMAKE_BINARY_DIR}}/{PCH_HEADER_NAME}")
 """
 
 
@@ -349,12 +355,13 @@ def _pch_compile_command(build_dir: Path, header: Path, gch: Path) -> list[str]
     except (OSError, json.JSONDecodeError) as err:
         _LOGGER.debug("No usable compile database, skipping pch: %s", err)
         return None
-    src_prefix = str(CORE.relative_src_path())
+    # Windows compile DBs use backslashes; normalize both sides
+    src_prefix = str(CORE.relative_src_path()).replace("\\", "/")
     entry = next(
         (
             e
             for e in entries
-            if e.get("file", "").startswith(src_prefix)
+            if e.get("file", "").replace("\\", "/").startswith(src_prefix)
             and e.get("file", "").endswith(_CXX_SOURCE_SUFFIXES)
         ),
         None,
@@ -420,6 +427,9 @@ def prepare_pch() -> None:
         return
     cmd = _pch_compile_command(build_dir, header, gch)
     if cmd is None:
+        # The checksum is stale; a leftover .gch must not be consumed
+        gch.unlink(missing_ok=True)
+        sum_path.unlink(missing_ok=True)
         return
     # Keyed on the checksum and the compile command: a failure caused by
     # the command alone must retry when the command changes
@@ -433,12 +443,14 @@ def prepare_pch() -> None:
         return
     try:
         result = subprocess.run(
-            cmd, cwd=build_dir, capture_output=True, text=True, check=False
+            cmd, cwd=build_dir, capture_output=True, text=True, check=False, timeout=300
         )
         error = None
         if result.returncode != 0:
             error = result.stderr.strip() or f"exit code {result.returncode}"
-    except OSError as err:
+        elif not gch.is_file():
+            error = "compiler produced no .gch"
+    except (OSError, subprocess.SubprocessError) as err:
         error = str(err)
     if error is not None:
         _LOGGER.warning(
@@ -448,9 +460,13 @@ def prepare_pch() -> None:
         sum_path.unlink(missing_ok=True)
         # Skip retries until a header/flag/sdkconfig/command change
         failed_marker.write_text(marker_key + "\n", encoding="utf-8")
+        os.utime(header)
         return
     failed_marker.unlink(missing_ok=True)
     sum_path.write_text(checksum + "\n", encoding="utf-8")
+    # The OBJECT_DEPENDS edge watches the header; bump it so consumers of
+    # the previous .gch recompile
+    os.utime(header)
 
 
 def write_project(

esphome/build_helpers/idedata.py

@@ -198,8 +198,10 @@ def parse_entry(
 
     it = iter(tokens[1:])
     for tok in it:
-        if tok in ("-c", "-o"):
-            next(it, None)  # drop the flag and its argument (input/output)
+        if tok in ("-c", "-o", "-include"):
+            # Drop the flag and its argument; the injected relative
+            # -include esphome_pch.h does not resolve outside the build dir
+            next(it, None)
         elif tok.startswith("-D"):
             # ``.strip()`` handles tokens like ``-D CONFIGURED=1`` (a single
             # quoted arg with a space after -D) that some flags arrive as.

tests/unit_tests/build_gen/test_espidf.py

@@ -500,6 +500,13 @@ def _make_pch_device(tmp_path: Path, name: str) -> Path:
         path = dev / "src" / header
         path.parent.mkdir(parents=True, exist_ok=True)
         path.write_text("")
+    # A real quoted include chain and a per-device-named sdkconfig with
+    # identical content: the closure and sdkconfig inputs must be exercised
+    (dev / "src" / "esphome" / "core" / "defines.h").write_text(
+        '#include "esphome/core/macros.h"\n'
+    )
+    (dev / "src" / "esphome" / "core" / "macros.h").write_text("#define M 1\n")
+    (dev / f"sdkconfig.{name}").write_text("CONFIG_X=y\n")
     build = dev / "build"
     build.mkdir(exist_ok=True)
     from esphome.build_helpers.pch import pch_header_text
@@ -736,3 +743,70 @@ def test_write_project_writes_pch_header(tmp_path: Path) -> None:
     assert (tmp_path / "build" / "esphome_pch.h").read_text() == pch_header_text(
         _PCH_HEADERS
     )
+
+
+def test_prepare_pch_stale_bailout_removes_gch(tmp_path: Path) -> None:
+    """A stale .gch must not survive when no compile command is available."""
+    from esphome.build_gen.espidf import prepare_pch
+
+    dev = _make_pch_device(tmp_path, "dev_s")
+    CORE.build_path = dev
+    gch = dev / "build" / "esphome_pch.h.gch"
+    gch.write_bytes(b"stale")
+    (dev / "build" / "esphome_pch.h.gch.sum").write_text("stale-sum\n")
+    (dev / "build" / "compile_commands.json").unlink()
+    with patch.object(CORE, "name", "test"):
+        prepare_pch()
+    assert not gch.exists()
+    assert not (dev / "build" / "esphome_pch.h.gch.sum").exists()
+
+
+def test_prepare_pch_zero_exit_without_gch_is_failure(tmp_path: Path) -> None:
+    from esphome.build_gen.espidf import prepare_pch
+
+    dev = _make_pch_device(tmp_path, "dev_z")
+    CORE.build_path = dev
+
+    def no_output(cmd, **kwargs):
+        return subprocess.CompletedProcess(cmd, 0, "", "")
+
+    with (
+        patch.object(CORE, "name", "test"),
+        patch("esphome.build_gen.espidf.subprocess.run", side_effect=no_output),
+    ):
+        prepare_pch()
+    assert not (dev / "build" / "esphome_pch.h.gch.sum").exists()
+    assert (dev / "build" / "esphome_pch.h.gch.failed").exists()
+
+
+def test_prepare_pch_bumps_header_for_object_depends(tmp_path: Path) -> None:
+    """The OBJECT_DEPENDS edge watches the header; a rebuilt .gch must bump
+    it so pch-consuming TUs recompile."""
+    import os as _os
+
+    from esphome.build_gen.espidf import prepare_pch
+
+    dev = _make_pch_device(tmp_path, "dev_t")
+    CORE.build_path = dev
+    header = dev / "build" / "esphome_pch.h"
+    gch = dev / "build" / "esphome_pch.h.gch"
+    _os.utime(header, (0, 0))
+    before = header.stat().st_mtime
+
+    def fake_compile(cmd, **kwargs):
+        gch.write_bytes(b"gch")
+        return subprocess.CompletedProcess(cmd, 0, "", "")
+
+    with (
+        patch.object(CORE, "name", "test"),
+        patch("esphome.build_gen.espidf.subprocess.run", side_effect=fake_compile),
+    ):
+        prepare_pch()
+    assert header.stat().st_mtime > before
+
+
+def test_component_cmakelists_pch_object_depends() -> None:
+    from esphome.build_gen.espidf import get_component_cmakelists
+
+    content = get_component_cmakelists()
+    assert 'OBJECT_DEPENDS "${CMAKE_BINARY_DIR}/esphome_pch.h"' in content