verbose gcc compiler error explanation

[Markus Schneider]

Hi there, 
I often encounter the problem, that I dont really know what to do, when my 
gcc compiler gives me an error message while compiling a c++ programm. 
 
Recently I got a "error: multiple types in one declaration" 
And it took me a really long time to figure out that I just forgot a 
semicolon after a class declaration. 
 
Is there anywhere a more detailed explanaition of gcc error messages? 
Maybe with a list of things i should check, when a certain error occurs? 
 
Thanks, 
Markus