[core] Fix placement new storage name for templated types (#15096)

esphome/cpp_generator.py

@@ -565,6 +565,29 @@ def new_variable(
     return obj
 
 
+def _extract_component_ns(type_str: str) -> str:
+    """Extract the component namespace from a fully-qualified C++ type string.
+
+    Strips leading ``esphome::`` and template arguments, then returns
+    the first namespace segment.  Falls back to ``"esphome"`` when the
+    type has no namespace qualifier (after stripping templates).
+
+    Examples::
+
+        esphome::dsmr::Dsmr                                        -> dsmr
+        esphome::logger::Logger                                     -> logger
+        esphome::Automation<std::optional<bool>, std::optional<bool>> -> esphome
+        Logger                                                      -> esphome
+    """
+    bare = type_str.removeprefix("esphome::")
+    # Strip template arguments before namespace extraction to avoid
+    # matching :: inside template params (e.g. Automation<std::optional<bool>>)
+    bare_no_template = bare.split("<", maxsplit=1)[0]
+    if "::" in bare_no_template:
+        return bare_no_template.split("::", maxsplit=1)[0].rstrip("_")
+    return "esphome"
+
+
 def Pvariable(id_: ID, rhs: SafeExpType, type_: "MockObj" = None) -> "MockObj":
     """Declare a new pointer variable in the code generation.
 
@@ -585,14 +608,7 @@ def Pvariable(id_: ID, rhs: SafeExpType, type_: "MockObj" = None) -> "MockObj":
         # to avoid heap fragmentation on embedded devices.
         the_type = id_.type
         # Extract component namespace from type for memory analysis attribution
-        type_str = str(the_type)
-        # Strip leading esphome:: to get the component namespace
-        # e.g. esphome::dsmr::Dsmr -> dsmr, logger::Logger -> logger
-        bare = type_str.removeprefix("esphome::")
-        if "::" in bare:
-            component_ns = bare.split("::", maxsplit=1)[0].rstrip("_")
-        else:
-            component_ns = "esphome"
+        component_ns = _extract_component_ns(str(the_type))
         storage_name = f"{component_ns}__{id_.id}__pstorage"
 
         # Declare aligned byte array for the object storage

tests/unit_tests/test_codegen.py

@@ -1,6 +1,7 @@
 import pytest
 
 from esphome import codegen as cg
+from esphome.cpp_generator import _extract_component_ns
 
 
 # Test interface remains the same.
@@ -75,3 +76,29 @@ from esphome import codegen as cg
 )
 def test_exists(attr):
     assert hasattr(cg, attr)
+
+
+@pytest.mark.parametrize(
+    ("type_str", "expected"),
+    (
+        ("esphome::dsmr::Dsmr", "dsmr"),
+        ("esphome::logger::Logger", "logger"),
+        ("esphome::web_server::WebServer", "web_server"),
+        ("esphome::deep_sleep::DeepSleep", "deep_sleep"),
+        ("esphome::Component", "esphome"),
+        ("Logger", "esphome"),
+        # Template types with :: in template args must not confuse extraction
+        (
+            "esphome::Automation<std::optional<bool>, std::optional<bool>>",
+            "esphome",
+        ),
+        (
+            "esphome::StatelessLambdaAction<std::optional<bool>, std::optional<bool>>",
+            "esphome",
+        ),
+        # Namespaced template type
+        ("esphome::sensor::Sensor<std::string>", "sensor"),
+    ),
+)
+def test_extract_component_ns(type_str, expected):
+    assert _extract_component_ns(type_str) == expected