编译器错误显示“函数未在此范围内声明”，但 function 是公开的

Question

我在 C++ 中的 Raspberry Pi Pico 上设置了一个 IRQ，但是当我编译我的代码时，它告诉我回调 function 是“未在此范围内声明”。 因为 function被宣布并且它是公开的，所以我已经用头撞墙好几个小时了。

#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/gpio.h"

uint64_t time_between_triggers;
uint16_t times_triggered;

void shaft_speed_init(uint8_t _gpio_number, uint8_t _precision, uint8_t _counts_per_turn){
    gpio_set_irq_enabled_with_callback(2, GPIO_IRQ_EDGE_RISE, true, &_shaft_speed_gpio_callback);

}

void _shaft_speed_gpio_callback(uint16_t _gpio, uint32_t _event_mask) {
    uint64_t trigger_time;
    static uint64_t prev_trigger_time;

    trigger_time = to_us_since_boot(get_absolute_time());
    time_between_triggers = time_between_triggers + (trigger_time - prev_trigger_time);
    prev_trigger_time = trigger_time;
    times_triggered++;
}

[main] Building folder: variable_rate_planter 
[build] Starting build
[proc] Executing command: /usr/bin/cmake --build /home/taylor/Documents/Programs/Pi-Pico/variable_rate_planter/build --config Debug --target all --
[build] [2/8  12% :: 0.017] Performing build step for 'PioasmBuild'
[build] ninja: no work to do.
[build] [3/8  25% :: 0.026] Performing build step for 'ELF2UF2Build'
[build] ninja: no work to do.
[build] [4/8  37% :: 0.043] No install step for 'PioasmBuild'
[build] [5/8  50% :: 0.052] No install step for 'ELF2UF2Build'
[build] [6/8  62% :: 0.083] Completed 'PioasmBuild'
[build] [6/8  75% :: 0.095] Completed 'ELF2UF2Build'
[build] [7/8  87% :: 0.201] Building CXX object CMakeFiles/vrp.dir/main.cpp.obj
[build] FAILED: CMakeFiles/vrp.dir/main.cpp.obj 
[build] /usr/bin/arm-none-eabi-g++ -DCFG_TUSB_DEBUG=1 -DCFG_TUSB_MCU=OPT_MCU_RP2040 -DCFG_TUSB_OS=OPT_OS_PICO -DLIB_PICO_BIT_OPS=1 -DLIB_PICO_BIT_OPS_PICO=1 -DLIB_PICO_DIVIDER=1 -DLIB_PICO_DIVIDER_HARDWARE=1 -DLIB_PICO_DOUBLE=1 -DLIB_PICO_DOUBLE_PICO=1 -DLIB_PICO_FIX_RP2040_USB_DEVICE_ENUMERATION=1 -DLIB_PICO_FLOAT=1 -DLIB_PICO_FLOAT_PICO=1 -DLIB_PICO_INT64_OPS=1 -DLIB_PICO_INT64_OPS_PICO=1 -DLIB_PICO_MALLOC=1 -DLIB_PICO_MEM_OPS=1 -DLIB_PICO_MEM_OPS_PICO=1 -DLIB_PICO_PLATFORM=1 -DLIB_PICO_PRINTF=1 -DLIB_PICO_PRINTF_PICO=1 -DLIB_PICO_RUNTIME=1 -DLIB_PICO_STANDARD_LINK=1 -DLIB_PICO_STDIO=1 -DLIB_PICO_STDIO_USB=1 -DLIB_PICO_STDLIB=1 -DLIB_PICO_SYNC=1 -DLIB_PICO_SYNC_CORE=1 -DLIB_PICO_SYNC_CRITICAL_SECTION=1 -DLIB_PICO_SYNC_MUTEX=1 -DLIB_PICO_SYNC_SEM=1 -DLIB_PICO_TIME=1 -DLIB_PICO_UNIQUE_ID=1 -DLIB_PICO_UTIL=1 -DPICO_BOARD=\"pico\" -DPICO_BUILD=1 -DPICO_CMAKE_BUILD_TYPE=\"Debug\" -DPICO_COPY_TO_RAM=0 -DPICO_CXX_ENABLE_EXCEPTIONS=0 -DPICO_NO_FLASH=0 -DPICO_NO_HARDWARE=0 -DPICO_ON_DEVICE=1 -DPICO_TARGET_NAME=\"vrp\" -DPICO_USE_BLOCKED_RAM=0 -I/home/taylor/pico/pico-sdk/src/common/pico_stdlib/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_gpio/include -I/home/taylor/pico/pico-sdk/src/common/pico_base/include -I/home/taylor/Documents/Programs/Pi-Pico/variable_rate_planter/build/generated/pico_base -I/home/taylor/pico/pico-sdk/src/boards/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_platform/include -I/home/taylor/pico/pico-sdk/src/rp2040/hardware_regs/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_base/include -I/home/taylor/pico/pico-sdk/src/rp2040/hardware_structs/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_claim/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_sync/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_irq/include -I/home/taylor/pico/pico-sdk/src/common/pico_sync/include -I/home/taylor/pico/pico-sdk/src/common/pico_time/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_timer/include -I/home/taylor/pico/pico-sdk/src/common/pico_util/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_uart/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_divider/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_runtime/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_clocks/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_resets/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_pll/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_vreg/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_watchdog/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_xosc/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_printf/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_bootrom/include -I/home/taylor/pico/pico-sdk/src/common/pico_bit_ops/include -I/home/taylor/pico/pico-sdk/src/common/pico_divider/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_double/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_int64_ops/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_float/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_malloc/include -I/home/taylor/pico/pico-sdk/src/rp2_common/boot_stage2/include -I/home/taylor/pico/pico-sdk/src/common/pico_binary_info/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_stdio/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_stdio_usb/include -I/home/taylor/pico/pico-sdk/lib/tinyusb/src -I/home/taylor/pico/pico-sdk/lib/tinyusb/src/common -I/home/taylor/pico/pico-sdk/lib/tinyusb/hw -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_fix/rp2040_usb_device_enumeration/include -I/home/taylor/pico/pico-sdk/src/rp2_common/pico_unique_id/include -I/home/taylor/pico/pico-sdk/src/rp2_common/hardware_flash/include -I/home/taylor/pico/pico-sdk/src/common/pico_usb_reset_interface/include -mcpu=cortex-m0plus -mthumb -Og -g -ffunction-sections -fdata-sections -fno-exceptions -fno-unwind-tables -fno-rtti -fno-use-cxa-atexit -MD -MT CMakeFiles/vrp.dir/main.cpp.obj -MF CMakeFiles/vrp.dir/main.cpp.obj.d -o CMakeFiles/vrp.dir/main.cpp.obj -c /home/taylor/Documents/Programs/Pi-Pico/variable_rate_planter/main.cpp
[build] In file included from /home/taylor/Documents/Programs/Pi-Pico/variable_rate_planter/main.cpp:4:
[build] /home/taylor/Documents/Programs/Pi-Pico/variable_rate_planter/shaft_speed.h: In function 'void shaft_speed_init(uint8_t, uint8_t, uint8_t)':
[build] /home/taylor/Documents/Programs/Pi-Pico/variable_rate_planter/shaft_speed.h:9:70: error: '_shaft_speed_gpio_callback' was not declared in this scope
[build]     9 |     gpio_set_irq_enabled_with_callback(2, GPIO_IRQ_EDGE_RISE, true, &_shaft_speed_gpio_callback);
[build]       |                                                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
[build] ninja: build stopped: subcommand failed.
[proc] The command: /usr/bin/cmake --build /home/taylor/Documents/Programs/Pi-Pico/variable_rate_planter/build --config Debug --target all -- exited with code: 1 and signal: null
[build] Build finished with exit code 1

Answer 1

您的 function _shaft_speed_gpio_callback似乎是在代码中使用它的位置之后定义的。 您需要添加一个 function 声明（又名“原型”），以便编译器知道名称指的是什么：

// Add this
void _shaft_speed_gpio_callback(uint16_t _gpio, uint32_t _event_mask);

// The rest of your code as provided
void shaft_speed_init(uint8_t _gpio_number, uint8_t _precision, uint8_t _counts_per_turn){
    gpio_set_irq_enabled_with_callback(2, GPIO_IRQ_EDGE_RISE, true, &_shaft_speed_gpio_callback);
}

void _shaft_speed_gpio_callback(uint16_t _gpio, uint32_t _event_mask) {
    // ...
}