[clang][dataflow] Add API to separate analysis from diagnosis

This patch adds an optional `PostVisitStmt` parameter to the `runTypeErasedDataflowAnalysis` function, which does one more pass over all

[clang][dataflow] Add API to separate analysis from diagnosis

This patch adds an optional `PostVisitStmt` parameter to the `runTypeErasedDataflowAnalysis` function, which does one more pass over all statements in the CFG after a fixpoint is reached. It then defines a `diagnose` method for the optional model in a new `UncheckedOptionalAccessDiagnosis` class, but only integrates that into the tests and not the actual optional check for `clang-tidy`. That will be done in a followup patch.

The primary motivation is to separate the implementation of the unchecked optional access check into two parts, to allow for further refactoring of just the model part later, while leaving the checking part alone. Currently there is duplication between the `transferUnwrapCall` and `diagnoseUnwrapCall` functions, but that will be dealt with in the followup.

Because diagnostics are now all gathered into one collection rather than being populated at each program point like when computing a fixpoint, this patch removes the usage of `Pair` and `UnorderedElementsAre` from the optional model tests, and instead modifies all their expectations to simply check the stringified set of diagnostics against a single string, either `"safe"` or some concatenation of `"unsafe: input.cc:y:x"`. This is not ideal as it loses any connection to the `/*[[check]]*/` annotations in the source strings, but it does still retain the source locations from the diagnostic strings themselves.

Reviewed By: sgatev, gribozavr2, xazax.hun

Differential Revision: https://reviews.llvm.org/D127898

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[clang][dataflow] Add support for correlated branches to optional model

Add support for correlated branches to the std::optional dataflow model.

Differential Revision: https://reviews.llvm.org/D125

[clang][dataflow] Add support for correlated branches to optional model

Add support for correlated branches to the std::optional dataflow model.

Differential Revision: https://reviews.llvm.org/D125931

Reviewed-by: ymandel, xazax.hun

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[clang][dataflow] In `optional` model, match call return via hasType

Currently the unchecked-optional-access model fails on this example:

#include <memory>
#include <optional>

void foo

[clang][dataflow] In `optional` model, match call return via hasType

Currently the unchecked-optional-access model fails on this example:

#include <memory>
#include <optional>

void foo() {
std::unique_ptr<std::optional<float>> x;
*x = std::nullopt;
}

You can verify the failure by saving the file as `foo.cpp` and running this command:

clang-tidy -checks='-*,bugprone-unchecked-optional-access' foo.cpp -- -std=c++17

The failing `assert` is in the `transferAssignment` function of the `UncheckedOptionalAccessModel.cpp` file:

assert(OptionalLoc != nullptr);

The symptom can be treated by replacing that `assert` with an early `return`:

if (OptionalLoc == nullptr)
return;

That would be better anyway since we cannot expect to always cover all possible LHS expressions, but it is out of scope for this patch and left as a followup.

Note that the failure did not occur on this very similar example:

#include <optional>

template <typename T>
struct smart_ptr {
T& operator*() &;
T* operator->();
};

void foo() {
smart_ptr<std::optional<float>> x;
*x = std::nullopt;
}

The difference is caused by the `isCallReturningOptional` matcher, which was previously checking the `functionDecl` of the `callee`. This patch changes it to instead use `hasType` directly on the call expression, fixing the failure for the `std::unique_ptr` example above.

Reviewed By: sgatev

Differential Revision: https://reviews.llvm.org/D127434

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[clang][dataflow] Track `optional` contents in `optional` model.

This patch adds partial support for tracking (i.e. modeling) the contents of an
optional value. Specifically, it supports tracking th

[clang][dataflow] Track `optional` contents in `optional` model.

This patch adds partial support for tracking (i.e. modeling) the contents of an
optional value. Specifically, it supports tracking the value after it is
accessed. We leave tracking constructed/assigned contents to a future patch.

Differential Revision: https://reviews.llvm.org/D124932

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[clang][dataflow] Modify `optional` model to handle type aliases.

Previously, type aliases were not handled (and resulted in an assertion
firing). This patch generalizes the model to consider aliase

[clang][dataflow] Modify `optional` model to handle type aliases.

Previously, type aliases were not handled (and resulted in an assertion
firing). This patch generalizes the model to consider aliases everywhere (a
previous patch already considered aliases for optional-returning functions).

Differential Revision: https://reviews.llvm.org/D126972

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[clang][dataflow] Model calls returning optionals

Model calls returning optionals

Differential Revision: https://reviews.llvm.org/D126759

Reviewed-by: ymandel, xazax.hun

[clang][dataflow] Add support for `value_or` in a comparison.

This patch adds limited modeling of the `value_or` method. Specifically, when
used in a particular idiom in a comparison to implicitly c

[clang][dataflow] Add support for `value_or` in a comparison.

This patch adds limited modeling of the `value_or` method. Specifically, when
used in a particular idiom in a comparison to implicitly check whether the
optional holds a value.

Differential Revision: https://reviews.llvm.org/D122231

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[clang][dataflow] Add support for disabling warnings on smart pointers.

This patch provides the user with the ability to disable all checked of accesses
to optionals that are the pointees of smart p

[clang][dataflow] Add support for disabling warnings on smart pointers.

This patch provides the user with the ability to disable all checked of accesses
to optionals that are the pointees of smart pointers. Since smart pointers are
not modeled (yet), the system cannot distinguish safe from unsafe accesses to
optionals through smart pointers. This results in false positives whenever
optionals are used through smart pointers. The patch gives the user the choice
of ignoring all positivess in these cases.

Differential Revision: https://reviews.llvm.org/D122143

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[clang][dataflow] Model the behavior of optional and std swap

Differential Revision: https://reviews.llvm.org/D122129

Reviewed-by: ymandel, xazax.hun

[clang][dataflow] Model the behavior of non-standard optional assignment

Model nullopt, value, and conversion assignment operators.

Reviewed-by: xazax.hun

Differential Revision: https://reviews.ll

[clang][dataflow] Model the behavior of non-standard optional assignment

Model nullopt, value, and conversion assignment operators.

Reviewed-by: xazax.hun

Differential Revision: https://reviews.llvm.org/D121863

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[clang][dataflow] Model the behavior of non-standard optional constructors

Model nullopt, inplace, value, and conversion constructors.

Reviewed-by: ymandel, xazax.hun, gribozavr2

Differential Revi

[clang][dataflow] Model the behavior of non-standard optional constructors

Model nullopt, inplace, value, and conversion constructors.

Reviewed-by: ymandel, xazax.hun, gribozavr2

Differential Revision: https://reviews.llvm.org/D121602

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[clang][dataflow] Model the behavior of various optional members

Model `make_optional`, optional's default constructor, `emplace`,
`reset`, and `operator bool` members.

Reviewed-by: xazax.hun

Diff

[clang][dataflow] Model the behavior of various optional members

Model `make_optional`, optional's default constructor, `emplace`,
`reset`, and `operator bool` members.

Reviewed-by: xazax.hun

Differential Revision: https://reviews.llvm.org/D121378

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[clang][dataflow] Add analysis that detects unsafe accesses to optionals

This commit reverts e0cc28dfdc67105974924cce42bb8c85bd44925a and moves
UncheckedOptionalAccessModelTest.cpp into clang/unitte

[clang][dataflow] Add analysis that detects unsafe accesses to optionals

This commit reverts e0cc28dfdc67105974924cce42bb8c85bd44925a and moves
UncheckedOptionalAccessModelTest.cpp into clang/unittests/Analysis/FlowSensitive,
to avoid build failures. The test will be moved back into a Models subdir
in a follow up patch that will address the build configuration issues.

Original description:

Adds a dataflow analysis that detects unsafe accesses to values of type
`std::optional`, `absl::optional`, or `base::Optional`.

Reviewed-by: ymandel, xazax.hun

Differential Revision: https://reviews.llvm.org/D121197

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