Compiler error: one_isr() causes a section type conflict with another_isr()

[titipc]

I have a project that needs to handle GPIO and time interruptions.
By compiling the code below I get:
exit status 1
void onTimer0() causes a section type conflict with void Button::isr()

Code: [Select all] [Expand/Collapse]

1. #define START_BUTTON 19 // gpio19    // Ligada ao botao start (iniciar ciclo)
2. #define STOP_BUTTON  23 // gpio23    // Ligada ao botal stop all
3.  
4. #include <FunctionalInterrupt.h>
5. class Button
6. {
7.   public:
8.     Button(uint8_t reqPin) : PIN(reqPin) {
9.       pinMode(PIN, INPUT_PULLUP);
10.       attachInterrupt(PIN, std::bind(&Button::isr, this), FALLING);
11.     };
12.     ~Button() {
13.       detachInterrupt(PIN);
14.     }
15.     void IRAM_ATTR isr() {
16.       //numberKeyPresses += 1;
17.       pressed = true;
18.     }
19.     bool checkPressed() {
20.       bool lastPressed;
21.       lastPressed = this->pressed;
22.       this->pressed = false;
23.       return lastPressed;
24.     }
25.   private:
26.     const uint8_t PIN;
27.     //volatile uint32_t numberKeyPresses;
28.     volatile bool pressed;
29.    
30. };
31. Button start_button(START_BUTTON);
32. Button stop_button(STOP_BUTTON);
33.  
34. #define LedI            2      // Esp32 Pin Led
35. byte ledI_flash=0;             // Internal led flash control
36.  
37. hw_timer_t * timer0 = NULL;    // timer to flash
38.  
39. void IRAM_ATTR onTimer0(){
40.       if (ledI_flash) digitalWrite(LedI, digitalRead(LedI) ^ 1);   // toggle LED pin
41. }
42.  
43. void setup() {
44.   // Setup timer
45.     timer0 = timerBegin(0, 24000, true); //timerID 0, div 80
46.     timerAttachInterrupt(timer0, &onTimer0, true);
47.     timerAlarmWrite(timer0, 5000, true);  
48.     timerAlarmEnable(timer0); // enable timer  
49.   // start flashing
50.     ledI_flash=1;
51. }
52.  
53. void loop() {
54.   // put your main code here, to run repeatedly:
55.      if (start_button.checkPressed()) ledI_flash=1;
56.      if (stop_button.checkPressed()) ledI_flash=0;
57. }

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If i remove IRAM_ATTR from one or both isr statements I succeed in compiling.

I'm using Arduino 1.8.9 and appreciate any help understanding the cause and solution.
Thanks,
Tiberio