There's a worse problem, which I've seen in the wild: int some_function(...); int some_other_function(...) { int r = -1; /* imagine

There's a worse problem, which I've seen in the wild: int some_function(...); int some_other_function(...) { int r = -1; /* imagine a bunch of other locals defined here */ r = some_function(...); if (-1 == r) { return -1; } ... } Now imagine someone changes the return type of some_function(): char *some_function(...); int some_other_function(...) { int r = -1; /* imagine a bunch of other locals defined here */ char *s; s = some_function(...); if (-1 == r) { return -1; } ... } Oops! Every other reference to r has been removed except the declaration and the test. Now some_other_function() will always take the early exit, and because r is initialized in its definition the compiler does not complain. (In real life, hilarity ensued.) If it was 'int r;' with no initializer this would have been caught by the compiler. Modern gcc is great at finding uninitialized and unused variables. -Wall -Wextra -Werror FTW. EDIT: referred to some_function() where it should have been some_other_function().