[wifi] Avoid .rodata RAM cost for ManualIP on ESP8266

On ESP8266, .rodata is mapped to DRAM (RAM), not flash. When
StructInitializer is used with all compile-time constant fields,
the compiler places the entire struct as a const blob in .rodata,
silently consuming ~20 bytes of RAM.

Switch to field-by-field assignment on ESP8266 so the IP address
values are encoded as immediate operands in flash instructions
instead of a .rodata blob. Other platforms continue to use the
aggregate initializer since their .rodata is flash-mapped.

esphome/components/wifi/__init__.py

@@ -439,13 +439,25 @@ def safe_ip(ip):
 def manual_ip(config):
     if config is None:
         return None
+    fields = {
+        "static_ip": CONF_STATIC_IP,
+        "gateway": CONF_GATEWAY,
+        "subnet": CONF_SUBNET,
+        "dns1": CONF_DNS1,
+        "dns2": CONF_DNS2,
+    }
+    if CORE.is_esp8266:
+        # On ESP8266, .rodata is mapped to RAM. Using StructInitializer with all
+        # compile-time constant fields causes the compiler to place a const blob
+        # in .rodata, silently consuming ~20 bytes of RAM. Field-by-field assignment
+        # encodes the values as immediate operands in flash instructions instead.
+        cg.add(cg.RawExpression("wifi::ManualIP manual_ip{}"))
+        for member, key in fields.items():
+            cg.add(cg.RawExpression(f"manual_ip.{member} = {safe_ip(config.get(key))}"))
+        return cg.RawExpression("manual_ip")
     return cg.StructInitializer(
         ManualIP,
-        ("static_ip", safe_ip(config[CONF_STATIC_IP])),
+        *((member, safe_ip(config.get(key))) for member, key in fields.items()),
-        ("gateway", safe_ip(config[CONF_GATEWAY])),
-        ("subnet", safe_ip(config[CONF_SUBNET])),
-        ("dns1", safe_ip(config.get(CONF_DNS1))),
-        ("dns2", safe_ip(config.get(CONF_DNS2))),
     )
 
 

tests/components/wifi/test.esp8266-ard.yaml

@@ -1,6 +1,12 @@
 wifi:
   min_auth_mode: WPA2
   post_connect_roaming: true
+  manual_ip:
+    static_ip: 192.168.1.100
+    gateway: 192.168.1.1
+    subnet: 255.255.255.0
+    dns1: 1.1.1.1
+    dns2: 8.8.8.8
 
 packages:
   - !include common.yaml