[button] Use a user provided default constructor

esphome/components/button/button.h

@@ -24,6 +24,9 @@ void log_button(const char *tag, const char *prefix, const char *type, Button *o
  */
 class Button : public EntityBase {
  public:
+  // User provided, not "= default": `new(p) Button()` would zero-fill .bss that is already zero.
+  Button() {}
+
   /** Press this button. This is called by the front-end.
    *
    * For implementing buttons, please override press_action.

esphome/components/number/number.h

@@ -28,7 +28,7 @@ class Number;
  */
 class Number : public EntityBase {
  public:
-  float state{};
+  float state;
 
   void publish_state(float state);
 

esphome/components/template/number/template_number.cpp

@@ -3,8 +3,6 @@
 
 namespace esphome::template_ {
 
-TemplateNumber::TemplateNumber() {}
-
 static const char *const TAG = "template.number";
 
 void TemplateNumber::setup() {

esphome/components/template/number/template_number.h

@@ -10,9 +10,6 @@ namespace esphome::template_ {
 
 class TemplateNumber final : public number::Number, public PollingComponent {
  public:
-  // User provided, not "= default": `new(p) TemplateNumber()` would zero-fill .bss that is already zero.
-  // Defined out of line so the member constructors are not inlined into every construction site.
-  TemplateNumber();
   template<typename F> void set_template(F &&f) { this->f_.set(std::forward<F>(f)); }
 
   void setup() override;