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Enable null pointer analysis inside lambdas. Include a diagnostic note due to known limitations with captured variables. #220

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Enable null pointer analysis inside lambdas. Include a diagnostic note due to known limitations with captured variables. #220

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29 changes: 29 additions & 0 deletions nullability/pointer_nullability_diagnosis.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -177,6 +177,18 @@ static const Expr* absl_nullable matchesNonConstCallNullCheck(
DynTypedNode::create(*ParentFunction), Ctx));
}

static const ValueDecl* absl_nullable getLambdaCapturedVariableDecl(
const Expr* absl_nonnull E) {
const DeclRefExpr* DeclRef = dyn_cast<DeclRefExpr>(E->IgnoreImpCasts());
if (DeclRef == nullptr) {
return nullptr;
}
if (!DeclRef->refersToEnclosingVariableOrCapture()) {
return nullptr;
}
return DeclRef->getDecl();
}

// Diagnoses whether `E` violates the expectation that it is nonnull.
static SmallVector<PointerNullabilityDiagnostic> diagnoseNonnullExpected(
const Expr* absl_nonnull E, const Environment& Env, ASTContext& Ctx,
Expand Down Expand Up @@ -227,6 +239,23 @@ static SmallVector<PointerNullabilityDiagnostic> diagnoseNonnullExpected(
}};
}

if (const ValueDecl* CapturedVarDecl = getLambdaCapturedVariableDecl(E)) {
return {
{.Code = PointerNullabilityDiagnostic::ErrorCode::ExpectedNonnull,
.Ctx = DiagCtx,
.Range = getRangeModuloMacros(Range, Ctx),
.Callee = Callee,
.ParamName = ParamName,
.NoteRange = getRangeModuloMacros(
CharSourceRange::getTokenRange(CapturedVarDecl->getSourceRange()),
Ctx),
.NoteMessage =
"This pointer is captured and dereferenced in a lambda. If it is "
"null-checked outside the lambda, consider capturing the pointee "
"by value or reference (possibly with an init capture). Otherwise "
"do a null check inside the lambda body to ensure null safety."}};
}

return {{
.Code = PointerNullabilityDiagnostic::ErrorCode::ExpectedNonnull,
.Ctx = DiagCtx,
Expand Down