From da046a988686b9cc08d29348992498c8f7260f5d Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 25 Aug 2026 15:16:54 -0500
Subject: [PATCH 1/2] Assert the forced-on working-ccache case emits no warning
 at all

The 'Not decoded' escape hatch could only mask a regression; assert the
captured records directly instead.
---
 tests/unit_tests/test_espidf_framework.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/unit_tests/test_espidf_framework.py b/tests/unit_tests/test_espidf_framework.py
index 8ef231aa3a..45a971ca01 100644
--- a/tests/unit_tests/test_espidf_framework.py
+++ b/tests/unit_tests/test_espidf_framework.py
@@ -1633,7 +1633,7 @@ def test_ccache_env_opt_in_with_working_binary(
     ):
         env = _ccache_env()
     assert env["IDF_CCACHE_ENABLE"] == "1"
-    assert "ccache" not in caplog.text.lower() or "Not decoded" in caplog.text
+    assert not [r for r in caplog.records if r.levelno >= logging.WARNING]
 
 
 def test_ccache_env_opt_in_with_rejected_binary(

From dc45cd4d3f713b0f29b77a38c436848467be9424 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 25 Aug 2026 15:27:53 -0500
Subject: [PATCH 2/2] Probe that the toolchain can load the gch before enabling
 the pch

---
 esphome/platformio/pch.py.script              | 26 +++++++++++++++++++
 .../unit_tests/test_platformio_pch_script.py  | 11 ++++----
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/esphome/platformio/pch.py.script b/esphome/platformio/pch.py.script
index 03f6567285..bb7d35708b 100644
--- a/esphome/platformio/pch.py.script
+++ b/esphome/platformio/pch.py.script
@@ -167,6 +167,32 @@ def _setup_pch() -> None:
             error = result.stderr if result.returncode != 0 else None
         except OSError as err:
             error = str(err)
+        if error is None:
+            # Some toolchains build a .gch they cannot load back (GCC 10 on
+            # macOS arm64 rejects it per-process: "had text segment at
+            # different address"); probe once so consumers never pay for a
+            # pch that every compile would silently reject
+            probe = subprocess.run(  # noqa: PLW1510
+                [
+                    cxx,
+                    *flags,
+                    "-MF",
+                    os.devnull,
+                    "-Winvalid-pch",
+                    "-include",
+                    str(header),
+                    "-fsyntax-only",
+                    "-x",
+                    "c++",
+                    "-",
+                ],
+                cwd=proj_dir,
+                input="",
+                capture_output=True,
+                text=True,
+            )
+            if ".gch" in probe.stderr:
+                error = f"toolchain cannot load the pch: {probe.stderr.strip()}"
         if error is not None:
             print("ESPHome: precompiled header failed; compiling without it")
             print(error)
diff --git a/tests/unit_tests/test_platformio_pch_script.py b/tests/unit_tests/test_platformio_pch_script.py
index 2ff162b565..ae3ad91099 100644
--- a/tests/unit_tests/test_platformio_pch_script.py
+++ b/tests/unit_tests/test_platformio_pch_script.py
@@ -56,7 +56,7 @@ class _FakeSConsEnv(dict):
 def _fake_cxx(tmp_path: Path, fail: bool = False) -> Path:
     """A compiler stand-in that records its argv and writes the -o target."""
     cxx = tmp_path / "fake-gxx"
-    body = 'printf \'%s\\n\' "$@" >> "$0.argv"\n'
+    body = 'printf -- ---call---\\\\n >> "$0.argv"; printf \'%s\\n\' "$@" >> "$0.argv"\n'
     if fail:
         body += "echo boom >&2\nexit 1\n"
     else:
@@ -109,10 +109,11 @@ def test_pch_script_preserves_spaced_flag_elements(tmp_path: Path) -> None:
     spaced.mkdir()
     flags = ['-DUSB_PRODUCT=\\"Pico 2W\\"', "-I", str(spaced), "-include", "other.h"]
     _run_script(tmp_path, flags=flags)
-    argv = (tmp_path / "fake-gxx.argv").read_text().splitlines()
-    assert '-DUSB_PRODUCT="Pico 2W"' in argv
-    assert str(spaced) in argv
-    assert "-include" not in argv
+    calls = (tmp_path / "fake-gxx.argv").read_text().split("---call---\n")
+    gch_call = next(c for c in calls if "c++-header" in c).splitlines()
+    assert '-DUSB_PRODUCT="Pico 2W"' in gch_call
+    assert str(spaced) in gch_call
+    assert "-include" not in gch_call
     # The stripped -include header is folded into the prefix header instead
     pch = (tmp_path / "dev" / "esphome_pch.h").read_text()
     assert pch.splitlines()[0] == '#include "other.h"'