cleanup

esphome/components/json/json_util.cpp

@@ -71,17 +71,25 @@ bool parse_json(const std::string &data, const json_parse_t &f) {
 }
 
 // JsonBuilder implementation
-JsonBuilder::JsonBuilder()
+JsonBuilder::JsonBuilder() {
-    : doc_(
 #ifdef USE_PSRAM
-          (allocator_ = std::make_unique<SpiRamAllocator>(), allocator_.get())
+  // Verify our storage is large enough (and log the actual size for reference)
+  static_assert(sizeof(SpiRamAllocator) <= sizeof(allocator_storage_), "allocator_storage_ too small");
+  // Note: sizeof(SpiRamAllocator) is typically around 24-32 bytes on ESP32
+  // Use placement new to construct SpiRamAllocator in the pre-allocated storage
+  auto *allocator = new (allocator_storage_) SpiRamAllocator();
+  doc_ = JsonDocument(allocator);
 #else
-          nullptr
+  doc_ = JsonDocument();
 #endif
-      ) {
 }
 
-JsonBuilder::~JsonBuilder() = default;
+JsonBuilder::~JsonBuilder() {
+#ifdef USE_PSRAM
+  // Explicitly call destructor for placement-new allocated object
+  reinterpret_cast<SpiRamAllocator *>(allocator_storage_)->~SpiRamAllocator();
+#endif
+}
 
 std::string JsonBuilder::serialize() {
   if (doc_.overflowed()) {

esphome/components/json/json_util.h

@@ -25,9 +25,6 @@ std::string build_json(const json_build_t &f);
 /// Parse a JSON string and run the provided json parse function if it's valid.
 bool parse_json(const std::string &data, const json_parse_t &f);
 
-// Forward declaration to avoid exposing implementation details
-struct SpiRamAllocator;
-
 /// Builder class for creating JSON documents without lambdas
 class JsonBuilder {
  public:
@@ -46,7 +43,9 @@ class JsonBuilder {
 
  private:
 #ifdef USE_PSRAM
-  std::unique_ptr<SpiRamAllocator> allocator_;  // One heap allocation, but keeps code clean
+  // Storage for SpiRamAllocator - typically around 24-32 bytes on ESP32
+  // Static assert in .cpp file ensures this is large enough
+  std::aligned_storage<32, alignof(void *)>::type allocator_storage_;
 #endif
   JsonDocument doc_;
   JsonObject root_;