C compiler: Error: syntax error - token "<token>" inserted before "<text>"

The description of the C compiler error E208 is generic as it does not clearly explain what is wrong. Furthermore, the source code line indicated by the error message is not necessarily where the root cause of the error is present. The cause of the error itself is often trivial.

Below are three use cases that trigger error E208, along with explanations of their root causes.

Use Case 1

The error occurs because the typedef uint15_t is not defined before.

uint15_t var_1;

Use Case 2

The error is triggered due to a typo in the function definition, where void has to be used instead of voiid.

voiid func(void)

Use Case 3

The error is triggered by a missing semicolon in the line int var_1.

int var_1
char var_2;

void func(void)
{
    //...
}

In this case, the error message refers to the line containing the opening curly bracket of the function definition, rather than the line containing the definition of the variable.

ctc E208: syntax error - token ";" inserted before "{"