[light] Keep the effect list in a flash table (#20204)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

tests/benchmarks/components/api/bench_list_entities.cpp

@@ -3,6 +3,8 @@
 #include "esphome/components/api/api_pb2.h"
 #include "esphome/components/api/api_buffer.h"
 #include "esphome/components/light/color_mode.h"
+#include "esphome/components/light/light_effect.h"
+#include "esphome/components/light/light_effect_names.h"
 
 namespace esphome::api::benchmarks {
 
@@ -150,7 +152,17 @@ BENCHMARK(CalcAndEncode_ListEntitiesBinarySensorResponse);
 // --- ListEntitiesLightResponse ---
 
 static light::ColorModeMask light_color_modes;
-static FixedVector<const char *> light_effects;
+
+class BenchEffect : public light::LightEffect {
+ public:
+  explicit BenchEffect(const char *name) : LightEffect(name) {}
+  void apply() override {}
+};
+static BenchEffect rainbow_effect("Rainbow");
+static BenchEffect strobe_effect("Strobe");
+static light::LightEffect *const LIGHT_EFFECT_TABLE[] = {&rainbow_effect, &strobe_effect};
+static const ConstVector<light::LightEffect *> light_effect_list(LIGHT_EFFECT_TABLE, 2);
+static const light::LightEffectNames light_effects(light_effect_list);
 
 static ListEntitiesLightResponse make_light_response() {
   // Initialize static data on first call
@@ -158,10 +170,6 @@ static ListEntitiesLightResponse make_light_response() {
   if (!initialized) {
     light_color_modes.insert(light::ColorMode::RGB_WHITE);
     light_color_modes.insert(light::ColorMode::COLOR_TEMPERATURE);
-    light_effects.init(3);
-    light_effects.push_back("None");
-    light_effects.push_back("Rainbow");
-    light_effects.push_back("Strobe");
     initialized = true;
   }
 

tests/component_tests/light/test_default_setters.py

@@ -2,6 +2,14 @@
 
 from collections.abc import Callable
 from pathlib import Path
+import re
+
+import pytest
+
+import esphome.codegen as cg
+from esphome.components import light
+from esphome.components.light import types as light_types
+from esphome.core import ID, EsphomeError
 
 
 def test_default_flash_length_and_empty_effects_are_not_emitted(
@@ -16,4 +24,20 @@ def test_default_flash_length_and_empty_effects_are_not_emitted(
     assert "bare_light->set_flash_transition_length(" not in main_cpp
     assert "bare_light->add_effects(" not in main_cpp
     assert "fancy_light->set_flash_transition_length(500);" in main_cpp
-    assert "fancy_light->add_effects({" in main_cpp
+    call = re.search(r"fancy_light->add_effects\((\w+), (\d+)\);", main_cpp)
+    assert call is not None
+    # The effect pointers form a flash table; they are address constants, not constexpr
+    assert re.search(
+        rf"static light::LightEffect \* const {call.group(1)}\[\] PROGMEM = \{{[^}}]+\}};",
+        main_cpp,
+    )
+
+
+def test_effect_assigned_in_setup_is_rejected() -> None:
+    """A pointer assigned in setup() would make the flash table need dynamic init."""
+    dynamic_effect = cg.Pvariable(
+        ID("dynamic_effect", is_declaration=True, type=light_types.LightEffect),
+        cg.RawExpression("make_effect()"),
+    )
+    with pytest.raises(EsphomeError, match="dynamic_effect"):
+        light._effects_table([dynamic_effect])

tests/components/light/common.yaml

@@ -32,6 +32,7 @@ esphome:
       - lambda: |-
           const auto &effects = id(test_monochromatic_light).get_effects();
           auto &same = id(test_monochromatic_light).get_effects();
+          const auto copy = id(test_monochromatic_light).get_effects();  // the view is copyable
           uint32_t total = effects.size();
           for (auto *effect : effects) {
             ESP_LOGD("test", "Effect %s", effect->get_name().c_str());
@@ -39,7 +40,7 @@ esphome:
           if (total > 0) {
             ESP_LOGD("test", "First %s", effects.at(0)->get_name().c_str());
             // Raw pointer iterators on purpose: external code binds std::find's result to `const auto *`
-            auto *it = std::find(same.begin(), same.end(), effects[0]);
+            auto *it = std::find(same.begin(), same.end(), copy[0]);
             ESP_LOGD("test", "Index %d", (int) (it - same.begin()));
           }
 

tests/components/light/test_light_state.cpp

@@ -1,6 +1,5 @@
 #include <gtest/gtest.h>
 
-#include "esphome/components/light/light_effect.h"
 #include "esphome/components/light/light_output.h"
 #include "esphome/components/light/light_state.h"
 
@@ -18,36 +17,8 @@ class BrightnessOutput : public LightOutput {
   void write_state(LightState *state) override {}
 };
 
-class NoopEffect : public LightEffect {
- public:
-  using LightEffect::LightEffect;
-  void apply() override {}
-};
-
-// start_effect_() is where the uint32_t index is narrowed to the stored uint16_t.
-class TestableLightState : public LightState {
- public:
-  using LightState::LightState;
-  using LightState::start_effect_;
-};
-
 }  // namespace
 
-// add_effects() is public, so an external component can exceed the codegen cap on effect count;
-// an index the uint16_t can't hold must be ignored rather than wrap onto another effect.
-TEST(LightStateEffect, IndexAboveUint16IsIgnoredAndKeepsTheActiveEffect) {
-  BrightnessOutput output;
-  TestableLightState state(&output);
-  NoopEffect effect("Noop");
-  state.add_effects({&effect});
-
-  state.start_effect_(1);
-  ASSERT_EQ(state.get_current_effect_index(), 1u);
-
-  state.start_effect_(0x10000u);  // unchecked narrowing wraps this to 0, which stops the effect
-  EXPECT_EQ(state.get_current_effect_index(), 1u);
-}
-
 // get_gamma_correct() reads the gamma codegen stores after the lookup table, rounded to two decimals.
 TEST(LightStateGamma, ReadsTheGammaStoredWithTheTable) {
   static constexpr GammaTable TABLE{{}, 280};

tests/unit_tests/test_cpp_generator.py

@@ -4,7 +4,7 @@ import math
 import pytest
 
 from esphome import cpp_generator as cg, cpp_types as ct
-from esphome.core import CORE, ID
+from esphome.core import CORE, ID, EsphomeError
 
 
 class TestExpressions:
@@ -829,6 +829,46 @@ class TestSharedProgmemArray:
         assert str(a) != str(b)
         assert sum("PROGMEM" in str(st) for st in CORE.global_statements) == 2
 
+    def test_is_static_pointer_only_for_placement_new(self) -> None:
+        CORE.config = {}
+        static = cg.new_Pvariable(ID("static_obj", is_declaration=True, type=ct.uint8))
+        dynamic = cg.Pvariable(
+            ID("dynamic_obj", is_declaration=True, type=ct.uint8),
+            cg.RawExpression("nullptr"),
+        )
+        assert cg.is_static_pointer(static)
+        assert not cg.is_static_pointer(dynamic)
+
+    def test_constexpr_and_const_arrays_are_not_shared(self) -> None:
+        CORE.config = {}
+        a = cg.shared_progmem_array("table", ct.uint8, [1], constexpr=False)
+        b = cg.shared_progmem_array("table", ct.uint8, [1])
+        assert str(a) != str(b)
+
+    def test_constexpr_false_rejects_dynamic_pointers(self) -> None:
+        CORE.config = {}
+        dynamic = cg.Pvariable(
+            ID("dynamic_obj", is_declaration=True, type=ct.uint8),
+            cg.RawExpression("nullptr"),
+        )
+        with pytest.raises(EsphomeError, match="dynamic_obj"):
+            cg.shared_progmem_array(
+                "table",
+                ct.uint8.operator("ptr"),
+                cg.ArrayInitializer(dynamic),
+                constexpr=False,
+            )
+
+    def test_constexpr_false_emits_a_const_array(self) -> None:
+        CORE.config = {}
+        cg.shared_progmem_array("table", ct.uint8, [1], constexpr=False)
+        (statement,) = (
+            str(st) for st in CORE.global_statements if "PROGMEM" in str(st)
+        )
+        assert statement.startswith(
+            "ESPHOME_FLASH_CONSTINIT static uint8_t const table[] PROGMEM = {1}"
+        )
+
     def test_same_contents_different_type_are_separate(self) -> None:
         CORE.config = {}
         a = cg.shared_progmem_array("table", ct.uint8, [1])