From 74b075d3cff8fea73f931880ace85af5cb621c7b Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 22 Dec 2025 07:03:17 -1000
Subject: [PATCH] [codegen] Add static storage class to global variables for
 size optimization (#12616)

---
 esphome/components/lvgl/__init__.py    |  2 ++
 esphome/components/lvgl/lvcode.py      |  4 ++--
 esphome/components/mapping/__init__.py |  2 +-
 esphome/cpp_generator.py               | 22 +++++++++++++++-------
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/esphome/components/lvgl/__init__.py b/esphome/components/lvgl/__init__.py
index 19c258fcd..c9cad1ac9 100644
--- a/esphome/components/lvgl/__init__.py
+++ b/esphome/components/lvgl/__init__.py
@@ -256,9 +256,11 @@ async def to_code(configs):
             True,
             type=lv_font_t.operator("ptr").operator("const"),
         )
+        # static=False because LV_FONT_CUSTOM_DECLARE creates an extern declaration
         cg.new_variable(
             globfont_id,
             MockObj(await lvalid.lv_font.process(default_font), "->").get_lv_font(),
+            static=False,
         )
         add_define("LV_FONT_DEFAULT", df.DEFAULT_ESPHOME_FONT)
     else:
diff --git a/esphome/components/lvgl/lvcode.py b/esphome/components/lvgl/lvcode.py
index c11597131..e2c70642a 100644
--- a/esphome/components/lvgl/lvcode.py
+++ b/esphome/components/lvgl/lvcode.py
@@ -337,7 +337,7 @@ def lv_Pvariable(type, name) -> MockObj:
     """
     if isinstance(name, str):
         name = ID(name, True, type)
-    decl = VariableDeclarationExpression(type, "*", name)
+    decl = VariableDeclarationExpression(type, "*", name, static=True)
     CORE.add_global(decl)
     var = MockObj(name, "->")
     CORE.register_variable(name, var)
@@ -353,7 +353,7 @@ def lv_variable(type, name) -> MockObj:
     """
     if isinstance(name, str):
         name = ID(name, True, type)
-    decl = VariableDeclarationExpression(type, "", name)
+    decl = VariableDeclarationExpression(type, "", name, static=True)
     CORE.add_global(decl)
     var = MockObj(name, ".")
     CORE.register_variable(name, var)
diff --git a/esphome/components/mapping/__init__.py b/esphome/components/mapping/__init__.py
index 94c7c10a8..a36b414fd 100644
--- a/esphome/components/mapping/__init__.py
+++ b/esphome/components/mapping/__init__.py
@@ -133,7 +133,7 @@ async def to_code(config):
         value_type,
     )
     var = MockObj(varid, ".")
-    decl = VariableDeclarationExpression(varid.type, "", varid)
+    decl = VariableDeclarationExpression(varid.type, "", varid, static=True)
     add_global(decl)
     CORE.register_variable(varid, var)
 
diff --git a/esphome/cpp_generator.py b/esphome/cpp_generator.py
index 1a47b346b..ddccb574e 100644
--- a/esphome/cpp_generator.py
+++ b/esphome/cpp_generator.py
@@ -51,15 +51,19 @@ class AssignmentExpression(Expression):
 
 
 class VariableDeclarationExpression(Expression):
-    __slots__ = ("type", "modifier", "name")
+    __slots__ = ("type", "modifier", "name", "static")
 
-    def __init__(self, type_, modifier, name):
+    def __init__(
+        self, type_: "MockObj", modifier: str, name: ID, *, static: bool = False
+    ) -> None:
         self.type = type_
         self.modifier = modifier
         self.name = name
+        self.static = static
 
-    def __str__(self):
-        return f"{self.type} {self.modifier}{self.name}"
+    def __str__(self) -> str:
+        prefix = "static " if self.static else ""
+        return f"{prefix}{self.type} {self.modifier}{self.name}"
 
 
 class ExpressionList(Expression):
@@ -507,13 +511,17 @@ def with_local_variable(id_: ID, rhs: SafeExpType, callback: Callable, *args) ->
     CORE.add(RawStatement("}"))  # output closing curly brace
 
 
-def new_variable(id_: ID, rhs: SafeExpType, type_: "MockObj" = None) -> "MockObj":
+def new_variable(
+    id_: ID, rhs: SafeExpType, type_: "MockObj" = None, *, static: bool = True
+) -> "MockObj":
     """Declare and define a new variable, not pointer type, in the code generation.
 
     :param id_: The ID used to declare the variable.
     :param rhs: The expression to place on the right hand side of the assignment.
     :param type_: Manually define a type for the variable, only use this when it's not possible
       to do so during config validation phase (for example because of template arguments).
+    :param static: If True (default), declare with static storage class for optimization.
+      Set to False when the variable must have external linkage (e.g., to match library declarations).
 
     :return: The new variable as a MockObj.
     """
@@ -522,7 +530,7 @@ def new_variable(id_: ID, rhs: SafeExpType, type_: "MockObj" = None) -> "MockObj
     obj = MockObj(id_, ".")
     if type_ is not None:
         id_.type = type_
-    decl = VariableDeclarationExpression(id_.type, "", id_)
+    decl = VariableDeclarationExpression(id_.type, "", id_, static=static)
     CORE.add_global(decl)
     assignment = AssignmentExpression(None, "", id_, rhs)
     CORE.add(assignment)
@@ -544,7 +552,7 @@ def Pvariable(id_: ID, rhs: SafeExpType, type_: "MockObj" = None) -> "MockObj":
     obj = MockObj(id_, "->")
     if type_ is not None:
         id_.type = type_
-    decl = VariableDeclarationExpression(id_.type, "*", id_)
+    decl = VariableDeclarationExpression(id_.type, "*", id_, static=True)
     CORE.add_global(decl)
     assignment = AssignmentExpression(None, None, id_, rhs)
     CORE.add(assignment)