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[clang-tidy] bugprone-unchecked-optional-access: handle BloombergLP::bdlb:NullableValue::makeValue to prevent false-positives #144313

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[clang-tidy] bugprone-unchecked-optional-access: handle BloombergLP::bdlb:NullableValue::makeValue to prevent false-positives #144313

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b2e5ee1
first iteration of fix
BaLiKfromUA Jun 16, 2025
cacdf75
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BaLiKfromUA Jun 16, 2025
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BaLiKfromUA Jun 16, 2025
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8 changes: 8 additions & 0 deletions ...ng-tidy/checkers/bugprone/Inputs/unchecked-optional-access/bde/types/bdlb_nullablevalue.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,14 @@ class NullableValue : public bsl::optional<T> {
const T &value() const &;
T &value() &;

constexpr T &makeValue();

template <typename U>
constexpr T &makeValue(U&& v);

template <typename... ARGS>
constexpr T &makeValueInplace(ARGS &&... args);

// 'operator bool' is inherited from bsl::optional

constexpr bool isNull() const noexcept;
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14 changes: 14 additions & 0 deletions clang-tools-extra/test/clang-tidy/checkers/bugprone/unchecked-optional-access.cpp
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Expand Up @@ -141,6 +141,20 @@ void nullable_value_after_swap(BloombergLP::bdlb::NullableValue<int> &opt1, Bloo
}
}

void nullable_value_make_value(BloombergLP::bdlb::NullableValue<int> &opt1, BloombergLP::bdlb::NullableValue<int> &opt2) {
if (opt1.isNull()) {
opt1.makeValue(42);
}

opt1.value();

if (opt2.isNull()) {
opt2.makeValueInplace(42);
}

opt2.value();
}

template <typename T>
void function_template_without_user(const absl::optional<T> &opt) {
opt.value(); // no-warning
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14 changes: 14 additions & 0 deletions clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
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Expand Up @@ -985,6 +985,20 @@ auto buildTransferMatchSwitch() {
isOptionalMemberCallWithNameMatcher(hasName("isNull")),
transferOptionalIsNullCall)

// NullableValue::makeValue, NullableValue::makeValueInplace
// Only NullableValue has these methods, but this
// will also pass for other types
.CaseOfCFGStmt<CXXMemberCallExpr>(
isOptionalMemberCallWithNameMatcher(
hasAnyName("makeValue", "makeValueInplace")),
[](const CXXMemberCallExpr *E, const MatchFinder::MatchResult &,
LatticeTransferState &State) {
if (RecordStorageLocation *Loc =
getImplicitObjectLocation(*E, State.Env)) {
setHasValue(*Loc, State.Env.getBoolLiteralValue(true), State.Env);
}
})

Comment on lines +988 to +1001
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I think configurable option is needed instead of hard code function name for non-std libarary.

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@BaLiKfromUA BaLiKfromUA Jun 16, 2025 •
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@HerrCai0907 I am happy to do so! Are there any examples how it looks for other clang-tidy checks?

Also, do you want to do it in scope of this PR or as a separate one?
Since non-std function names (e.g. hasValue) are also processed for folly::Optional in code above my change.

Thanks for review!

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You can look at no-malloc check for similar option with function names.

You can add function-lists both for bdlb and other libraries. The code must be very similar.

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@BaLiKfromUA BaLiKfromUA Jun 23, 2025 •
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@vbvictor, thank you for the help! I checked the implementation of no-malloc configuration, and it does make sense to me.

Just want to double-check expectation, do we want to have a configuration like this, with just method names (name of options is subject to change):

NonStdMakeValue: makeValue;makeValueInplace. // BloombergLP::bdlb:NullableValue
NonStdHasValue: hasValue. // folly::Optional
NonStdNoValue: isNull. // BloombergLP::bdlb:NullableValue

Or do we want to specify which class method belongs to:

NonStdMakeValue: BloombergLP::bdlb:NullableValue::makeValue;BloombergLP::bdlb:NullableValue::makeValueInplace.
NonStdHasValue: folly::Optional::hasValue. 
NonStdNoValue: BloombergLP::bdlb:NullableValue::isNull.

For me, the first version looks better because:

  • It's easier
  • It makes it possible to easily enable this check for more "make value" custom methods in classes inherited from the optional.

However, it's less intuitive to me than option two because different non-standard methods belong to different classes. But this is how it works now, so maybe we could build on top of it, just with method names, and then improve it or extend it.

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@vbvictor vbvictor Jun 24, 2025 •
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I'd prefer 2nd option because we have more control over what method belong to what class. Imagine this situation:

struct optional1() {
   hasNull(); // check that it has value but it's nullptr
   isNull(); // check that it has no value inside
}

struct optional2() {
   hasNull(); // check that it has no value inside
}

If we go with 1st option, we would write NonStdNoValue: hasNull;isNull, but that would produce errors because optional1::hasNull doesn't actually check for no value, optional1::isNull does.
To express intentional behavior, we need to write NonStdNoValue: optional2::hasNull;optional1::isNull.

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@vbvictor vbvictor Jun 24, 2025 •
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But if it works like option1 right now, I don't oppose implementing option1.
I suppose we could harden it in the future if ever needed. My example with optional1 and optional2 wouldn't likely appear in real life IMO.

// optional::emplace
.CaseOfCFGStmt<CXXMemberCallExpr>(
isOptionalMemberCallWithNameMatcher(hasName("emplace")),
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