Commit Graph

4207 Commits

Author SHA1 Message Date
Endre Fülöp 141cb8a1ee [analyzer] Model iterator random incrementation symmetrically
Summary:
In case a pointer iterator is incremented in a binary plus expression
(operator+), where the iterator is on the RHS, IteratorModeling should
now detect, and track the resulting value.

Reviewers: Szelethus, baloghadamsoftware

Reviewed By: baloghadamsoftware

Subscribers: rnkovacs, whisperity, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, Charusso, steakhal, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83190
2020-08-04 11:04:12 +02:00
Denys Petrov 86e1b73507 [analyzer] Simplify function SVal::getAsSymbolicExpression and similar ones
Summary: Simplify functions SVal::getAsSymbolicExpression SVal::getAsSymExpr and SVal::getAsSymbol. After revision I concluded that `getAsSymbolicExpression` and `getAsSymExpr` repeat functionality of `getAsSymbol`, thus them can be removed.

Fix: Remove functions SVal::getAsSymbolicExpression and SVal::getAsSymExpr.

Differential Revision: https://reviews.llvm.org/D85034
2020-08-03 15:03:35 +03:00
Balázs Kéri b22b97b3d0 [Analyzer] Use of BugType in DereferenceChecker (NFC).
Use of BuiltinBug is replaced by BugType.
Class BuiltinBug seems to have no benefits and is confusing.

Reviewed By: Szelethus, martong, NoQ, vsavchenko

Differential Revision: https://reviews.llvm.org/D84494
2020-07-30 08:33:12 +02:00
Kirstóf Umann 032b78a076 [analyzer] Revert the accidental commit of D82122
Was accidentally squished into
rGb6cbe6cb0399d4671e5384dcc326af56bc6bd122. The assert fires on the code
snippet included in this commit.

More discussion can be found in https://reviews.llvm.org/D82598.
2020-07-24 21:33:18 +02:00
Balázs Kéri 65fd651980 [Analyzer][StreamChecker] Use BugType::SuppressOnSink at resource leak report.
Summary:
Use the built-in functionality BugType::SuppressOnSink
instead of a manual solution in StreamChecker.

Differential Revision: https://reviews.llvm.org/D83120
2020-07-23 11:53:25 +02:00
Valeriy Savchenko e63b488f27 [analyzer][solver] Track symbol disequalities
Summary:
This commmit adds another relation that we can track separately from
range constraints.  Symbol disequality can help us understand that
two equivalence classes are not equal to each other.  We can generalize
this knowledge to classes because for every a,b,c, and d that
a == b, c == d, and b != c it is true that a != d.

As a result, we can reason about other equalities/disequalities of symbols
that we know nothing else about, i.e. no constraint ranges associated
with them.  However, we also benefit from the knowledge of disequal
symbols by following the rule:
  if a != b and b == C where C is a constant, a != C
This information can refine associated ranges for different classes
and reduce the number of false positives and paths to explore.

Differential Revision: https://reviews.llvm.org/D83286
2020-07-22 13:02:39 +03:00
Valeriy Savchenko b13d9878b8 [analyzer][solver] Track symbol equivalence
Summary:
For the most cases, we try to reason about symbol either based on the
information we know about that symbol in particular or about its
composite parts.  This is faster and eliminates costly brute force
searches through existing constraints.

However, we do want to support some cases that are widespread enough
and involve reasoning about different existing constraints at once.
These include:
  * resoning about 'a - b' based on what we know about 'b - a'
  * reasoning about 'a <= b' based on what we know about 'a > b' or 'a < b'

This commit expands on that part by tracking symbols known to be equal
while still avoiding brute force searches.  It changes the way we track
constraints for individual symbols.  If we know for a fact that 'a == b'
then there is no need in tracking constraints for both 'a' and 'b' especially
if these constraints are different.  This additional relationship makes
dead/live logic for constraints harder as we want to maintain as much
information on the equivalence class as possible, but we still won't
carry the information that we don't need anymore.

Differential Revision: https://reviews.llvm.org/D82445
2020-07-22 13:02:39 +03:00
Valeriy Savchenko f531c1c7c0 [analyzer] Introduce small improvements to the solver infra
Summary:
* Add a new function to delete points from range sets.
* Introduce an internal generic interface for range set intersections.
* Remove unnecessary bits from a couple of solver functions.
* Add in-code sections.

Differential Revision: https://reviews.llvm.org/D82381
2020-07-22 13:02:39 +03:00
Nithin Vadukkumchery Rajendrakumar 76c0577763 [Analyzer] Handle unique_ptr::swap() in SmartPtrModeling
Summary:
    Implemented modeling for unique_ptr::swap() SmartPtrModeling

    Subscribers: xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, Charusso, martong, ASDenysPetrov, cfe-commits

    Reviewers: NoQ, Szelethus, vsavchenko, xazax.hun
    Reviewed By: NoQ, vsavchenko, xazax.hun

    Tags: #clang

    Differential Revision: https://reviews.llvm.org/D8387
2020-07-21 12:05:27 +02:00
Nithin Vadukkumchery Rajendrakumar a560910211 [Analyzer] Add checkRegionChanges for SmartPtrModeling
Summary:
    Implemented checkRegionChanges for SmartPtrModeling

    Reviewers: NoQ, Szelethus, vsavchenko, xazax.hun

    Reviewed By: NoQ, vsavchenko, xazax.hun

    Subscribers: martong, cfe-commits
    Tags: #clang

    Differential Revision: https://reviews.llvm.org/D83836
2020-07-21 01:13:40 +02:00
Gabor Marton 3ff220de90 [analyzer][StdLibraryFunctionsChecker] Add POSIX networking functions
Summary:
Adding networking functions from the POSIX standard (2017). This includes
functions that deal with sockets from socket.h, netdb.h.

In 'socket.h' of some libc implementations (e.g. glibc) with C99, sockaddr
parameter is a transparent union of the underlying sockaddr_ family of pointers
instead of being a pointer to struct sockaddr. In these cases, the standardized
signature will not match, thus we try to match with another signature that has
the joker Irrelevant type. In the case of transparent unions, we also not add
those constraints which require pointer types for the sockaddr param.

Interestingly, in 'netdb.h' sockaddr is not handled as a transparent union.

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83407
2020-07-20 22:46:24 +02:00
Benjamin Kramer 33c9d0320e Upgrade SmallSets of pointer-like types to SmallPtrSet
This is slightly more efficient. NFC.
2020-07-20 16:54:29 +02:00
Balázs Kéri 9b7c43d341 [Analyzer][StreamChecker] Report every leak, clean up state.
Summary:
Report resource leaks with non-fatal error.
Report every resource leak.
Stream state is cleaned up at `checkDeadSymbols`.

Reviewers: Szelethus, baloghadamsoftware, NoQ

Reviewed By: Szelethus

Subscribers: rnkovacs, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, gamesh411, Charusso, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82845
2020-07-20 11:49:00 +02:00
Adam Balogh a59d4ae431 [Analyzer] Hotfix for various crashes in iterator checkers
The patch that introduces handling iterators implemented as pointers may
cause crash in some projects because pointer difference is mistakenly
handled as pointer decrement. (Similair case for iterators implemented
as class instances are already handled correctly.) This patch fixes this
issue.

The second case that causes crash is comparison of an iterator
implemented as pointer and a null-pointer. This patch contains a fix for
this issue as well.

The third case which causes crash is that the checker mistakenly
considers all integers as nonloc::ConcreteInt when handling an increment
or decrement of an iterator implemented as pointers. This patch adds a
fix for this too.

The last case where crashes were detected is when checking for success
of an std::advance() operation. Since the modeling of iterators
implemented as pointers is still incomplete this may result in an
assertion. This patch replaces the assertion with an early exit and
adds a FIXME there.

Differential Revision: https://reviews.llvm.org/D83295
2020-07-16 20:49:33 +02:00
Logan Smith 2c2a297bb6 [clang][NFC] Add 'override' keyword to virtual function overrides
This patch adds override to several overriding virtual functions that were missing the keyword within the clang/ directory. These were found by the new -Wsuggest-override.
2020-07-14 08:59:57 -07:00
Benjamin Kramer 724afa5a33 [analyzer] Inline StringSet that's defined in a header
That's just asking for ODR violations. Also drop a call to lower()
that's not needed.
2020-07-13 23:51:05 +02:00
Artem Dergachev cb6c110614 [analyzer] Silence a warning.
An old clang warns that the const object has no default constructor so it may
remain uninitialized forever. That's a false alarm because all fields
have a default initializer. Apply the suggested fixit anyway.
2020-07-10 13:25:46 -07:00
Zhi Zhuang 4d4d903767 Fix warning caused by __builtin_expect_with_probability was not handled
in places such as constant folding

Previously some places that should have handled
__builtin_expect_with_probability is missing, so in some case it acts
differently than __builtin_expect.
For example it was not handled in constant folding, thus in the
following program, the "if" condition should be constantly true and
folded, but previously it was not handled and cause warning "control may
reach end of non-void function" (while __builtin_expect does not):

__attribute__((noreturn)) extern void bar();
int foo(int x, int y) {
  if (y) {
    if (__builtin_expect_with_probability(1, 1, 1))
      bar();
  }
  else
    return 0;
}

Now it's fixed.

Differential Revisions: https://reviews.llvm.org/D83362
2020-07-09 08:01:33 -07:00
Benjamin Kramer b44470547e Make helpers static. NFC. 2020-07-09 13:48:56 +02:00
Mikael Holmen cfcf8e17ef [analyzer] Silence gcc -Wparentheses warning [NFC] 2020-07-08 10:23:59 +02:00
Nithin Vadukkumchery Rajendrakumar 20e271a98d [analyzer] Warning for default constructed unique_ptr dereference
Summary: Add support for warning incase of default constructed unique pointer dereferences

Reviewed By: NoQ, Szelethus, vsavchenko, xazax.hun

Tags: #clang

Differential Revision: https://reviews.llvm.org/D81315
2020-07-08 09:51:02 +02:00
Nathan James 41bbb875e4
[NFC] Use hasAnyName matcher in place of anyOf(hasName()...) 2020-07-07 14:31:04 +01:00
Raphael Isemann 7308e14326 [clang] Fix modules build after D82585
Just getting the bots running again.

See the D82585 for more info.
2020-07-06 17:51:53 +02:00
Kirstóf Umann cfd6b4b811 [analyzer] Don't allow hidden checkers to emit diagnostics
Hidden checkers (those marked with Hidden in Checkers.td) are meant for
development purposes only, and are only displayed under
-analyzer-checker-help-developer, so users shouldn't see reports from them.

I moved StdLibraryFunctionsArg checker to the unix package from apiModeling as
it violated this rule. I believe this change doesn't deserve a different
revision because it is in alpha, and the name is so bad anyways I don't
immediately care where it is, because we'll have to revisit it soon enough.

Differential Revision: https://reviews.llvm.org/D81750
2020-07-06 15:34:51 +02:00
Kirstóf Umann b295607697 [analyzer][NFC] Don't allow dependency checkers to emit diagnostics
The thrilling conclusion to the barrage of patches I uploaded lately! This is a
big milestone towards the goal set out in http://lists.llvm.org/pipermail/cfe-dev/2019-August/063070.html.
I hope to accompany this with a patch where the a coreModeling package is added,
from which package diagnostics aren't allowed either, is an implicit dependency
of all checkers, and the core package for the first time can be safely disabled.

Differential Revision: https://reviews.llvm.org/D78126
2020-07-06 14:51:37 +02:00
Kirstóf Umann 690ff37a28 [analyzer] Force dependency checkers to be hidden
Since strong dependencies aren't user-facing (its hardly ever legal to disable
them), lets enforce that they are hidden. Modeling checkers that aren't
dependencies are of course not impacted, but there is only so much you can do
against developers shooting themselves in the foot :^)

I also made some changes to the test files, reversing the "test" package for,
well, testing.

Differential Revision: https://reviews.llvm.org/D81761
2020-07-06 13:05:45 +02:00
Kirstóf Umann b6cbe6cb03 [analyzer][NFC] Move the data structures from CheckerRegistry to the Core library
If you were around the analyzer for a while now, you must've seen a lot of
patches that awkwardly puts code from one library to the other:

* D75360 moves the constructors of CheckerManager, which lies in the Core
  library, to the Frontend library. Most the patch itself was a struggle along
  the library lines.
* D78126 had to be reverted because dependency information would be utilized
  in the Core library, but the actual data lied in the frontend.
  D78126#inline-751477 touches on this issue as well.

This stems from the often mentioned problem: the Frontend library depends on
Core and Checkers, Checkers depends on Core. The checker registry functions
(`registerMallocChecker`, etc) lie in the Checkers library in order to keep each
checker its own module. What this implies is that checker registration cannot
take place in the Core, but the Core might still want to use the data that
results from it (which checker/package is enabled, dependencies, etc).

D54436 was the patch that initiated this. Back in the days when CheckerRegistry
was super dumb and buggy, it implemented a non-documented solution to this
problem by keeping the data in the Core, and leaving the logic in the Frontend.
At the time when the patch landed, the merger to the Frontend made sense,
because the data hadn't been utilized anywhere, and the whole workaround without
any documentation made little sense to me.

So, lets put the data back where it belongs, in the Core library. This patch
introduces `CheckerRegistryData`, and turns `CheckerRegistry` into a short lived
wrapper around this data that implements the logic of checker registration. The
data is tied to CheckerManager because it is required to parse it.

Side note: I can't help but cringe at the fact how ridiculously awkward the
library lines are. I feel like I'm thinking too much inside the box, but I guess
this is just the price of keeping the checkers so modularized.

Differential Revision: https://reviews.llvm.org/D82585
2020-07-04 12:31:51 +02:00
Gabor Marton db4d5f7048 [analyzer][StdLibraryFunctionsChecker] Add POSIX file handling functions
Adding file handling functions from the POSIX standard (2017).
A new checker option is introduced to enable them.
In follow-up patches I am going to upstream networking, pthread, and other
groups of POSIX functions.

Differential Revision: https://reviews.llvm.org/D82288
2020-07-02 14:28:05 +02:00
Aaron Ballman d4cf4c66b5 Fix some typos (unkown -> unknown); NFC 2020-07-02 06:41:05 -04:00
Adam Balogh 9e63b190af [Analyzer] Handle pointer implemented as iterators in iterator checkers
Iterators are an abstraction of pointers and in some data structures
iterators may be implemented by pointers. This patch adds support for
iterators implemented as pointers in all the iterator checkers
(including iterator modeling).

Differential Revision: https://reviews.llvm.org/D82185
2020-07-01 09:04:28 +02:00
Adam Balogh ea563daae5 [Analyzer] Fix errors in iterator modeling
There is major a bug found in iterator modeling: upon adding a value
to or subtracting a value from an iterator the position of the original
iterator is also changed beside the result. This patch fixes this bug.

To catch such bugs in the future we also changed the tests to look for
regular expressions including an end-of-line symbol (`$`) so we can
prevent false matches where only the tested prefix matches.

Another minor bug is that when printing the state, all the iterator
positions are printed in a single line. This patch also fixes this.

Differential Revision: https://reviews.llvm.org/D82385
2020-07-01 09:04:28 +02:00
Balazs Benics de361df3f6 [analyzer][Z3-refutation] Fix a refutation BugReporterVisitor bug
FalsePositiveRefutationBRVisitor had a bug where the constraints were not
properly collected thus crosschecked with Z3.
This patch demonstratest and fixes that bug.

Bug:
The visitor wanted to collect all the constraints on a BugPath.
Since it is a visitor, it stated the visitation of the BugPath with the node
before the ErrorNode. As a final step, it visited the ErrorNode explicitly,
before it processed the collected constraints.

In principle, the ErrorNode should have visited before every other node.
Since the constraints were collected into a map, mapping each symbol to its
RangeSet, if the map already had a mapping with the symbol, then it was skipped.

This behavior was flawed if:
We already had a constraint on a symbol, but at the end in the ErrorNode we have
a tighter constraint on that. Therefore, this visitor would not utilize that
tighter constraint during the crosscheck validation.

Differential Revision: https://reviews.llvm.org/D78457
2020-06-29 18:51:24 +02:00
Dmitri Gribenko a44425f25b Revert "[analyzer][NFC] Add unittest for FalsePositiveRefutationBRVisitor"
This reverts commit e22cae32c5. It broke
the build:

FalsePositiveRefutationBRVisitorTest.cpp:112:3: error: use of undeclared identifier 'LLVM_WITH_Z3'
2020-06-29 17:00:15 +02:00
Balazs Benics e22cae32c5 [analyzer][NFC] Add unittest for FalsePositiveRefutationBRVisitor
Adds the test infrastructure for testing the FalsePositiveRefutationBRVisitor.
It will be extended in the D78457 patch, which demonstrates and fixes a bug in
the visitor.

Differential Revision: https://reviews.llvm.org/D78704
2020-06-29 16:54:17 +02:00
Balázs Kéri d1df560231 [Analyzer][StreamChecker] Use BugType instead of BuiltinBug (NFC) .
Summary:
I do not like the BuiltinBug class.
And it takes no SuppressOnSink parameter that may be needed in the future.

Reviewers: Szelethus, baloghadamsoftware, gamesh411

Reviewed By: Szelethus

Subscribers: rnkovacs, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, gamesh411, Charusso, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82741
2020-06-29 15:37:13 +02:00
Nithin Vadukkumchery Rajendrakumar 37c1bf21d1 [analyzer] Enable constructor support in evalCall event.
Pass EvalCallOptions via runCheckersForEvalCall into defaultEvalCall.
Update the AnalysisOrderChecker to support evalCall for testing.

Differential Revision: https://reviews.llvm.org/D82256
2020-06-25 09:47:13 -07:00
Valentin Clement d90443b1d9 [openmp] Base of tablegen generated OpenMP common declaration
Summary:
As discussed previously when landing patch for OpenMP in Flang, the idea is
to share common part of the OpenMP declaration between the different Frontend.
While doing this it was thought that moving to tablegen instead of Macros will also
give a cleaner and more powerful way of generating these declaration.
This first part of a future series of patches is setting up the base .td file for
DirectiveLanguage as well as the OpenMP version of it. The base file is meant to
be used by other directive language such as OpenACC.
In this first patch, the Directive and Clause enums are generated with tablegen
instead of the macros on OMPConstants.h. The next pacth will extend this
to other enum and move the Flang frontend to use it.

Reviewers: jdoerfert, DavidTruby, fghanim, ABataev, jdenny, hfinkel, jhuber6, kiranchandramohan, kiranktp

Reviewed By: jdoerfert, jdenny

Subscribers: arphaman, martong, cfe-commits, mgorny, yaxunl, hiraditya, guansong, jfb, sstefan1, aaron.ballman, llvm-commits

Tags: #llvm, #openmp, #clang

Differential Revision: https://reviews.llvm.org/D81736
2020-06-23 10:32:32 -04:00
Balázs Kéri e935a540ea [Analyzer][StreamChecker] Add note tags for file opening.
Summary:
Bug reports of resource leak are now improved.
If there are multiple resource leak paths for the same stream,
only one wil be reported.

Reviewers: Szelethus, xazax.hun, baloghadamsoftware, NoQ

Reviewed By: Szelethus, NoQ

Subscribers: NoQ, rnkovacs, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, gamesh411, Charusso, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D81407
2020-06-22 11:15:35 +02:00
Kirstóf Umann 1614e35408 [analyzer][MallocChecker] PR46253: Correctly recognize standard realloc
https://bugs.llvm.org/show_bug.cgi?id=46253

This is an obvious hack because realloc isn't any more affected than other
functions modeled by MallocChecker (or any user of CallDescription really),
but the nice solution will take some time to implement.

Differential Revision: https://reviews.llvm.org/D81745
2020-06-16 17:50:06 +02:00
Valeriy Savchenko 14b947f306 [analyzer] Fix StdLibraryFunctionsChecker crash on macOS
Summary:
EOF macro token coming from a PCH file on macOS while marked as literal,
doesn't contain any literal data.  This causes crash on every project
using PCHs.

This commit doesn't resolve the problem with PCH (maybe it was
designed like this for a purpose) or with `tryExpandAsInteger`, but
rather simply shoots off a crash itself.

Differential Revision: https://reviews.llvm.org/D81916
2020-06-16 16:10:07 +03:00
Haojian Wu e00dcf61a2 NFC: cleanup the "(void)" case trick since the assertion is wrapped in NDEBUG. 2020-06-16 09:46:29 +02:00
Jan Korous a93ff1826b [Analyzer][NFC] Remove prefix from WebKitNoUncountedMemberChecker name 2020-06-15 14:13:56 -07:00
Jan Korous a7eb3692e7 [Analyzer][WebKit] UncountedCallArgsChecker
Differential Revision: https://reviews.llvm.org/D77179
2020-06-15 13:53:36 -07:00
Denys Petrov e1741e34e0 [analyzer] Reasoning about comparison expressions in RangeConstraintManager
Summary:

Implemented RangeConstraintManager::getRangeForComparisonSymbol which handles comparison operators.
RangeConstraintManager::getRangeForComparisonSymbol cares about the sanity of comparison expressions sequences helps reasonably to branch an exploded graph.
It can significantly reduce the graph and speed up the analysis. For more details, please, see the differential revision.

This fixes https://bugs.llvm.org/show_bug.cgi?id=13426

Differential Revision: https://reviews.llvm.org/D78933
2020-06-15 18:35:15 +03:00
Balázs Kéri efa8b6e884 [Analyzer][StreamChecker] Add check for pointer escape.
Summary:
After an escaped FILE* stream handle it is not possible to make
reliable checks on it because any function call can have effect
on it.

Reviewers: Szelethus, baloghadamsoftware, martong, NoQ

Reviewed By: NoQ

Subscribers: NoQ, rnkovacs, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, gamesh411, Charusso, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D80699
2020-06-15 15:43:23 +02:00
Sterling Augustine e64059828f Revert "[analyzer][NFC] Don't allow dependency checkers to emit diagnostics"
Summary:
This reverts commit 33fb9cbe21.

That commit violates layering by adding a dependency from StaticAnalyzer/Core
back to StaticAnalyzer/FrontEnd, creating a circular dependency.

I can't see a clean way to fix it except refactoring.

Reviewers: echristo, Szelethus, martong

Subscribers: xazax.hun, baloghadamsoftware, szepet, rnkovacs, a.sidorin, mikhail.ramalho, donat.nagy, dkrupp, Charusso, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D81752
2020-06-12 12:10:13 -07:00
Jacques Pienaar 270d580a0e [analyzer] Avoid unused variable warning in opt build 2020-06-12 09:48:49 -07:00
Haojian Wu e4b3fc18d3 Get rid of -Wunused warnings in release build, NFC. 2020-06-12 15:42:29 +02:00
Kirstóf Umann 33fb9cbe21 [analyzer][NFC] Don't allow dependency checkers to emit diagnostics
The thrilling conclusion to the barrage of patches I uploaded lately! This is a
big milestone towards the goal set out in http://lists.llvm.org/pipermail/cfe-dev/2019-August/063070.html.
I hope to accompany this with a patch where the a coreModeling package is added,
from which package diagnostics aren't allowed either, is an implicit dependency
of all checkers, and the core package for the first time can be safely disabled.

Differential Revision: https://reviews.llvm.org/D78126
2020-06-12 14:59:48 +02:00
Kirstóf Umann e22f1c02a2 [analyzer] Introduce weak dependencies to express *preferred* checker callback evaluation order
Checker dependencies were added D54438 to solve a bug where the checker names
were incorrectly registered, for example, InnerPointerChecker would incorrectly
emit diagnostics under the name MallocChecker, or vice versa [1]. Since the
system over the course of about a year matured, our expectations of what a role
of a dependency and a dependent checker should be crystallized a bit more --
D77474 and its summary, as well as a variety of patches in the stack
demonstrates how we try to keep dependencies to play a purely modeling role. In
fact, D78126 outright forbids diagnostics under a dependency checkers name.

These dependencies ensured the registration order and enabling only when all
dependencies are satisfied. This was a very "strong" contract however, that
doesn't fit the dependency added in D79420. As its summary suggests, this
relation is directly in between diagnostics, not modeling -- we'd prefer a more
specific warning over a general one.

To support this, I added a new dependency kind, weak dependencies. These are not
as strict of a contract, they only express a preference in registration order.
If a weak dependency isn't satisfied, the checker may still be enabled, but if
it is, checker registration, and transitively, checker callback evaluation order
is ensured.

If you are not familiar with the TableGen changes, a rather short description
can be found in the summary of D75360. A lengthier one is in D58065.

[1] https://www.youtube.com/watch?v=eqKeqHRAhQM

Differential Revision: https://reviews.llvm.org/D80905
2020-06-12 14:08:38 +02:00