On 10/05/17 02:24, Eric Gallager wrote: > Sorry if this is a stupid question, but could you explain how this > warning is different from -Wbad-function-cast? Something about direct > calls to functions vs. passing them as function pointers?
No, it is not :) -Wbad-function-cast is IMHO a strange legacy warning. It is C-only, and it triggers only if the result of a function call is cast to a type with a different TREE_CODE, so for instance int <-> float <-> pointer. It would trigger for perfectly valid code like this: i = (int) floor (f); while we have no warning for i = floor (f); What I want to diagnose is assigning a function pointer via an explicit type cast to another function pointer, when there is no possible implicit conversion between the two function pointer types. Thus the cast was used to silence a warning/error in the first place. The idea for this warning came up when someone spotted a place in openssl, where a type cast was used to change the return value of a callback function from long to int: https://github.com/openssl/openssl/issues/4413 But due to the type cast there was never ever any warning from this invalid type cast. Bernd.
