Andriy
I wonder if coccinelle can help me with the following issue.
There is a type, let's call it sometype_t, that is typedef-ed to int.
I have spent a lot of time looking at this issue from a static analysis
point of view.
The two most common cases are:
1) sometype_t should be treated as a type that is not compatible with
any other type. I don't think you want to do this?
2) the type of sometype_t could change in the future and the code
should not contain any implicit dependencies on the type it currently
has (this occurs frequently with size_t).
Given:
int f(int a);
int g(sometype_t b);
sometype_t x, y;
int z;
x = z; // you want to flag this?
x = (sometype_t)z; // is this ok?
z = x; // what do you want to do about this?
x = 0; // a common case, do you really want to flag this?
// Requiring people add a cast will make you unpopular.
x = y + z; // arithmetic conversion probably makes this work ok
...x ? y : z ... // the biggest smoking gun
x = (int)y; // or perhaps this one is
if (x < z) ; // is a relational op equivalent to assignment?
if (x == y) ; // equality ops are usually treated as equivalent
g(any_of_the_above_rhs_assignment_expression); // treat same as assignment?
f(x); // flag f as having the 'wrong' parameter type?
Any cases I missed?
There is an API which uses that type consistently to provide for possible future
extensions. But that there are many lax users of that API which frequently use
int instead of sometype_t.
For example, sometimes a sometype_t variable is assigned with int value, or
conversely a sometype_t value is assigned to int variable, or int value is
passed
in a function parameter where sometype_t is expected.
I wonder if I could use the power of coccinelle to easily find and perhaps even
fix such lax type handling.
Thanks!
--
Derek M. Jones tel: +44 (0) 1252 520 667
Knowledge Software Ltd mailto:[email protected]
Source code analysis http://www.knosof.co.uk
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