warning: implicit declaration of function 'gs_set_gpio' [-Wimplicit-function-declaration]

这个警告的含义是在当前编译单元中，编译器无法找到名为'gs_set_gpio'的函数的声明。这意味着在调用该函数之前，没有在代码中显式地声明它。根据引用和引用的解释，如果函数只有定义而没有声明，会直接报错；如果函数有定义但没有声明，会出现警告。在这种情况下，编译器默认会隐式声明函数，但是这样的隐式声明在C99标准中是无效的。因此，编译器会给出警告，提示需要在调用函数之前进行声明。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
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