GCC, functions, and pointer arguments, warning behaviour

Posted by James Morris on Stack Overflow See other posts from Stack Overflow or by James Morris
Published on 2010-06-03T08:00:03Z Indexed on 2010/06/03 8:04 UTC
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I've recently updated to a testing distribution, which is now using GCC 4.4.3. Now I've set everything up, I've returned to coding and have built my project and I get one of these horrible messages:

*** glibc detected *** ./boxyseq: free(): invalid pointer: 0x0000000001d873e8 ***

I absolutely know what is wrong here, but was rather confused as to when I saw my C code where I call a function which frees a dynamically allocated data structure - I had passed it an incompatible pointer type - a pointer to a completely different data structure.

warning: passing argument 1 of 'data_A_free' from incompatible pointer type
note: expected 'struct data_A *' but argument is of type 'struct data_B *'

I'm confused because I'm sure this would have been an error before and compilation would never have completed. Is this not just going to make life more difficult for C programmers?

Can I change it back to an error without making a whole bunch of other warnings errors too?

Or am I loosing the plot and it's always been a warning?

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