Merge remote-tracking branch 'upstream/fix-fan-action-trigger-args' into integration

esphome/components/fan/__init__.py

@@ -358,21 +358,29 @@ async def fan_turn_on_to_code(config, action_id, template_arg, args):
         (CONF_DIRECTION, "set_direction", FanDirection),
     )
 
+    # Normalize trigger args to `const std::remove_cvref_t<T> &` so the
+    # apply lambda and any inner field lambdas (generated below via
+    # `process_lambda`) share one parameter spelling that's well-formed for
+    # any T (value, ref, or const-ref). Matches TurnOnAction::ApplyFn.
+    normalized_args = [
+        (cg.RawExpression(f"const std::remove_cvref_t<{cg.safe_exp(t)}> &"), n)
+        for t, n in args
+    ]
+
     fwd_args = ", ".join(name for _, name in args)
     body_lines: list[str] = []
     for conf_key, setter, type_ in FIELDS:
         if (value := config.get(conf_key)) is None:
             continue
         if isinstance(value, Lambda):
-            inner = await cg.process_lambda(value, args, return_type=type_)
+            inner = await cg.process_lambda(value, normalized_args, return_type=type_)
             body_lines.append(f"call.{setter}(({inner})({fwd_args}));")
         else:
             body_lines.append(f"call.{setter}({cg.safe_exp(value)});")
 
-    # Match TurnOnAction::ApplyFn signature: const Ts &... for trigger args.
     apply_args = [
         (FanCall.operator("ref"), "call"),
-        *((t.operator("const").operator("ref"), n) for t, n in args),
+        *normalized_args,
     ]
     apply_lambda = LambdaExpression(
         ["\n".join(body_lines)],

esphome/components/fan/automation.h

@@ -12,9 +12,16 @@ namespace fan {
 // plus one parent pointer, regardless of how many fields the user set.
 // Trigger args are forwarded to the apply function so user lambdas
 // (e.g. `speed: !lambda "return x;"`) keep working.
+//
+// Trigger args are normalized to `const std::remove_cvref_t<Ts> &...` so
+// the codegen can emit a matching parameter list for both the apply lambda
+// and any inner field lambdas without producing invalid C++ source text
+// (e.g. `const T & &` if Ts already carries a reference, or `const const
+// T &` if Ts already carries a const). This keeps trigger args no-copy
+// regardless of whether the trigger supplies `T`, `T &`, or `const T &`.
 template<typename... Ts> class TurnOnAction : public Action<Ts...> {
  public:
-  using ApplyFn = void (*)(FanCall &, const Ts &...);
+  using ApplyFn = void (*)(FanCall &, const std::remove_cvref_t<Ts> &...);
   TurnOnAction(Fan *state, ApplyFn apply) : state_(state), apply_(apply) {}
 
   void play(const Ts &...x) override {

tests/components/fan/common.yaml

@@ -9,6 +9,14 @@ fan:
     has_oscillating: true
     has_direction: true
     speed_count: 3
+    # Exercise fan.turn_on inside a trigger whose Ts pack is non-empty
+    # (StringRef from on_preset_set) so the apply-lambda + inner-lambda
+    # codegen runs through the cvref-normalized path.
+    on_preset_set:
+      then:
+        - fan.turn_on:
+            id: test_fan
+            speed: !lambda "return x.empty() ? 1 : 3;"
 
 # Test lambdas using get_preset_mode() which returns StringRef
 # These examples match the migration guide in the PR description
@@ -88,3 +96,21 @@ button:
       - fan.turn_on:
           id: test_fan
           speed: !lambda 'return 1;'
+
+# Exercise fan.turn_on inside triggers with non-empty Ts:
+#  - number.on_value: Ts = float (Python value type; previously raised
+#    AttributeError on .operator("const"))
+#  - fan.on_preset_set: Ts = StringRef (already a value-type wrapper around
+#    a const char * + size; tests the cvref-normalized inner-lambda path)
+number:
+  - platform: template
+    id: fan_speed_number
+    optimistic: true
+    min_value: 1
+    max_value: 3
+    step: 1
+    on_value:
+      then:
+        - fan.turn_on:
+            id: test_fan
+            speed: !lambda "return (int) x;"