[core] Fix substitution id redefinition false positive (#11603)

esphome/config.py

@@ -319,6 +319,9 @@ def iter_ids(config, path=None):
             yield from iter_ids(item, path + [i])
     elif isinstance(config, dict):
         for key, value in config.items():
+            if len(path) == 0 and key == CONF_SUBSTITUTIONS:
+                # Ignore IDs in substitution definitions.
+                continue
             if isinstance(key, core.ID):
                 yield key, path
             yield from iter_ids(value, path + [key])

tests/unit_tests/core/test_config.py

@@ -261,6 +261,17 @@ def test_device_duplicate_id(
     assert "ID duplicate_device redefined!" in captured.out
 
 
+def test_substitution_with_id(
+    yaml_file: Callable[[str], str], capsys: pytest.CaptureFixture[str]
+) -> None:
+    """Test that a ids coming from substitutions do not cause false positive ID redefinition."""
+    load_config_from_fixture(
+        yaml_file, "id_collision_with_substitution.yaml", FIXTURES_DIR
+    )
+    captured = capsys.readouterr()
+    assert "ID some_switch_id redefined!" not in captured.out
+
+
 def test_add_platform_defines_priority() -> None:
     """Test that _add_platform_defines runs after globals.
 

tests/unit_tests/fixtures/core/config/id_collision_with_substitution.yaml

@@ -0,0 +1,12 @@
+esphome:
+  name: test
+
+host:
+
+substitutions:
+  support_switches:
+    - platform: gpio
+      id: some_switch_id
+      pin: 12
+
+switch: $support_switches