While the original check's purpose is to identify potentially dangerous
functions based on the parameter types (as identifier names do not mean
anything when it comes to the language rules), unfortunately, such a plain
interface check rule can be incredibly noisy. While the previous
"filtering heuristic" is able to find many similar usages, there is an entire
class of parameters that should not be warned about very easily mixed by that
check: parameters that have a name and their name follows a pattern,
e.g. `text1, text2, text3, ...`.`
This patch implements a simple, but powerful rule, that allows us to detect
such cases and ensure that no warnings are emitted for parameter sequences that
follow a pattern, even if their types allow for them to be potentially mixed at a call site.
Given a threshold `k`, warnings about two parameters are filtered from the
result set if the names of the parameters are either prefixes or suffixes of
each other, with at most k letters difference on the non-common end.
(Assuming that the names themselves are at least `k` long.)
- The above `text1, text2` is an example of this. (Live finding from Xerces.)
- `LHS` and `RHS` are also fitting the bill here. (Live finding from... virtually any project.)
- So does `Qmat, Tmat, Rmat`. (Live finding from I think OpenCV.)
Reviewed By: aaron.ballman
Differential Revision: http://reviews.llvm.org/D97297
There are several types of functions and various reasons why some
"swappable parameters" cannot be fixed with changing the parameters' types, etc.
The most common example might be int `min(int a, int b)`... no matter what you
do, the two parameters must remain the same type.
The **filtering heuristic** implemented in this patch deals with trying to find
such functions during the modelling and building of the swappable parameter
range.
If the parameter currently scrutinised matches either of the predicates below,
it will be regarded as **not swappable** even if the type of the parameter
matches.
Reviewed By: aaron.ballman
Differential Revision: http://reviews.llvm.org/D78652
Adds a relaxation option ModelImplicitConversions which will make the check
report for cases where parameters refer to types that are implicitly
convertible to one another.
Example:
struct IntBox { IntBox(int); operator int(); };
void foo(int i, double d, IntBox ib) {}
Implicit conversions are the last to model in the set of things that are
reasons for the possibility of a function being called the wrong way which is
not always immediately apparent when looking at the function (signature or
call).
Reviewed By: aaron.ballman, martong
Differential Revision: http://reviews.llvm.org/D75041
Whisperity