The Called-Once dataflow analysis could never terminate as a
consequence of non-monotonic update on states. States of kind Escape
can override states leading to non-monotonic update.
This fix disallows the `Escape` state to override the `Reported`
state.
rdar://119671856
We have a new policy in place making links to private resources
something we try to avoid in source and test files. Normally, we'd
organically switch to the new policy rather than make a sweeping change
across a project. However, Clang is in a somewhat special circumstance
currently: recently, I've had several new contributors run into rdar
links around test code which their patch was changing the behavior of.
This turns out to be a surprisingly bad experience, especially for
newer folks, for a handful of reasons: not understanding what the link
is and feeling intimidated by it, wondering whether their changes are
actually breaking something important to a downstream in some way,
having to hunt down strangers not involved with the patch to impose on
them for help, accidental pressure from asking for potentially private
IP to be made public, etc. Because folks run into these links entirely
by chance (through fixing bugs or working on new features), there's not
really a set of problematic links to focus on -- all of the links have
basically the same potential for causing these problems. As a result,
this is an omnibus patch to remove all such links.
This was not a mechanical change; it was done by manually searching for
rdar, radar, radr, and other variants to find all the various
problematic links. From there, I tried to retain or reword the
surrounding comments so that we would lose as little context as
possible. However, because most links were just a plain link with no
supporting context, the majority of the changes are simple removals.
Differential Review: https://reviews.llvm.org/D158071
Cleanup attribute allows users to attach a destructor-like functions
to variable declarations to be called whenever they leave the scope.
The logic of such functions is not supported by the Clang's CFG and
is too hard to be reasoned about. In order to avoid false positives
in this situation, we assume that we didn't see ALL of the executtion
paths of the function and, thus, can warn only about multiple call
violation.
rdar://74441906
Differential Revision: https://reviews.llvm.org/D98694
This patch introduces a very simple inter-procedural analysis
between blocks and enclosing functions.
We always analyze blocks first (analysis is done as part of semantic
analysis that goes side-by-side with the parsing process), and at the
moment of reporting we don't know how that block will be actually
used.
This patch introduces new logic delaying reports of the "never called"
warnings on blocks. If we are not sure that the block will be called
exactly once, we shouldn't warn our users about that. Double calls,
however, don't require such delays. While analyzing the enclosing
function, we can actually decide what we should do with those
warnings.
Additionally, as a side effect, we can be more confident about blocks
in such context and can treat them not as escapes, but as direct
calls.
rdar://74090107
Differential Revision: https://reviews.llvm.org/D98688
This commit makes escapes symmetrical, meaning that having escape
before and after the branching, where parameter is not called on
one of the paths, will have the same effect.
Differential Revision: https://reviews.llvm.org/D98622
It is very common to check callbacks and completion handlers for null.
This patch supports such checks using built-in functions:
* __builtin_expect
* __builtin_expect_with_probablity
* __builtin_unpredictable
rdar://73455388
Differential Revision: https://reviews.llvm.org/D96268
This commit introduces a new attribute `called_once`.
It can be applied to function-like parameters to signify that
this parameter should be called exactly once. This concept
is particularly widespread in asynchronous programs.
Additionally, this commit introduce a new group of dataflow
analysis-based warnings to check this property. It identifies
and reports the following situations:
* parameter is called twice
* parameter is never called
* parameter is not called on one of the paths
Current implementation can also automatically infer `called_once`
attribute for completion handler paramaters that should follow the
same principle by convention. This behavior is OFF by default and
can be turned on by using `-Wcompletion-handler`.
Differential Revision: https://reviews.llvm.org/D92039
rdar://72812043
