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//===- unittests/StaticAnalyzer/FalsePositiveRefutationBRVisitorTest.cpp --===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "CheckerRegistration.h"
#include "Reusables.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Frontend/AnalysisConsumer.h"
#include "clang/StaticAnalyzer/Frontend/CheckerRegistry.h"
#include "llvm/Config/llvm-config.h"
#include "gtest/gtest.h"
namespace clang {
namespace ento {
namespace {
class FalsePositiveGenerator : public Checker<eval::Call> {
using Self = FalsePositiveGenerator;
const BuiltinBug FalsePositiveGeneratorBug{this, "FalsePositiveGenerator"};
using HandlerFn = bool (Self::*)(const CallEvent &Call,
CheckerContext &) const;
CallDescriptionMap<HandlerFn> Callbacks = {
{{"reachedWithContradiction", 0}, &Self::reachedWithContradiction},
{{"reachedWithNoContradiction", 0}, &Self::reachedWithNoContradiction},
{{"reportIfCanBeTrue", 1}, &Self::reportIfCanBeTrue},
};
bool report(CheckerContext &C, ProgramStateRef State,
StringRef Description) const {
ExplodedNode *Node = C.generateNonFatalErrorNode(State);
if (!Node)
return false;
auto Report = std::make_unique<PathSensitiveBugReport>(
FalsePositiveGeneratorBug, Description, Node);
C.emitReport(std::move(Report));
return true;
}
bool reachedWithNoContradiction(const CallEvent &, CheckerContext &C) const {
return report(C, C.getState(), "REACHED_WITH_NO_CONTRADICTION");
}
bool reachedWithContradiction(const CallEvent &, CheckerContext &C) const {
return report(C, C.getState(), "REACHED_WITH_CONTRADICTION");
}
// Similar to ExprInspectionChecker::analyzerEval except it emits warning only
// if the argument can be true. The report emits the report in the state where
// the assertion true.
bool reportIfCanBeTrue(const CallEvent &Call, CheckerContext &C) const {
// A specific instantiation of an inlined function may have more constrained
// values than can generally be assumed. Skip the check.
if (C.getPredecessor()->getLocationContext()->getStackFrame()->getParent())
return false;
SVal AssertionVal = Call.getArgSVal(0);
if (AssertionVal.isUndef())
return false;
ProgramStateRef State = C.getPredecessor()->getState();
ProgramStateRef StTrue;
std::tie(StTrue, std::ignore) =
State->assume(AssertionVal.castAs<DefinedOrUnknownSVal>());
if (StTrue)
return report(C, StTrue, "CAN_BE_TRUE");
return false;
}
public:
bool evalCall(const CallEvent &Call, CheckerContext &C) const {
if (const HandlerFn *Callback = Callbacks.lookup(Call))
return (this->*(*Callback))(Call, C);
return false;
}
};
void addFalsePositiveGenerator(AnalysisASTConsumer &AnalysisConsumer,
AnalyzerOptions &AnOpts) {
AnOpts.CheckersAndPackages = {{"test.FalsePositiveGenerator", true},
{"debug.ViewExplodedGraph", false}};
AnalysisConsumer.AddCheckerRegistrationFn([](CheckerRegistry &Registry) {
Registry.addChecker<FalsePositiveGenerator>(
"test.FalsePositiveGenerator", "EmptyDescription", "EmptyDocsUri");
});
}
class FalsePositiveRefutationBRVisitorTestBase : public testing::Test {
public:
void SetUp() override {
#ifndef LLVM_WITH_Z3
GTEST_SKIP() << "Requires the LLVM_ENABLE_Z3_SOLVER cmake option.";
#endif
}
};
// C++20 use constexpr below.
const std::vector<std::string> LazyAssumeArgs{
"-Xclang", "-analyzer-config", "-Xclang", "eagerly-assume=false"};
const std::vector<std::string> LazyAssumeAndCrossCheckArgs{
"-Xclang", "-analyzer-config", "-Xclang", "eagerly-assume=false",
"-Xclang", "-analyzer-config", "-Xclang", "crosscheck-with-z3=true"};
TEST_F(FalsePositiveRefutationBRVisitorTestBase, UnSatInTheMiddleNoReport) {
constexpr auto Code = R"(
void reachedWithContradiction();
void reachedWithNoContradiction();
void test(int x, int y) {
if (x * y == 0)
return;
reachedWithNoContradiction();
if (x == 0) {
reachedWithContradiction();
// x * y != 0 => x != 0 && y != 0 => contradict with x == 0
}
})";
std::string Diags;
EXPECT_TRUE(runCheckerOnCodeWithArgs<addFalsePositiveGenerator>(
Code, LazyAssumeAndCrossCheckArgs, Diags));
EXPECT_EQ(Diags,
"test.FalsePositiveGenerator:REACHED_WITH_NO_CONTRADICTION\n");
// Single warning. The second report was invalidated by the visitor.
// Without enabling the crosscheck-with-z3 both reports are displayed.
std::string Diags2;
EXPECT_TRUE(runCheckerOnCodeWithArgs<addFalsePositiveGenerator>(
Code, LazyAssumeArgs, Diags2));
EXPECT_EQ(Diags2,
"test.FalsePositiveGenerator:REACHED_WITH_NO_CONTRADICTION\n"
"test.FalsePositiveGenerator:REACHED_WITH_CONTRADICTION\n");
}
TEST_F(FalsePositiveRefutationBRVisitorTestBase,
UnSatAtErrorNodeWithNewSymbolNoReport) {
constexpr auto Code = R"(
void reportIfCanBeTrue(bool);
void reachedWithNoContradiction();
void test(int x, int y) {
if (x * y == 0)
return;
// We know that 'x * y': {[MIN,-1], [1,MAX]}
reachedWithNoContradiction();
reportIfCanBeTrue(x == 0); // contradiction
// The function introduces the 'x == 0' constraint in the ErrorNode which
// leads to contradiction with the constraint of 'x * y'.
// Note that the new constraint was bound to a new symbol 'x'.
})";
std::string Diags;
EXPECT_TRUE(runCheckerOnCodeWithArgs<addFalsePositiveGenerator>(
Code, LazyAssumeAndCrossCheckArgs, Diags));
EXPECT_EQ(Diags,
"test.FalsePositiveGenerator:REACHED_WITH_NO_CONTRADICTION\n");
// Single warning. The second report was invalidated by the visitor.
// Without enabling the crosscheck-with-z3 both reports are displayed.
std::string Diags2;
EXPECT_TRUE(runCheckerOnCodeWithArgs<addFalsePositiveGenerator>(
Code, LazyAssumeArgs, Diags2));
EXPECT_EQ(Diags2,
"test.FalsePositiveGenerator:REACHED_WITH_NO_CONTRADICTION\n"
"test.FalsePositiveGenerator:CAN_BE_TRUE\n");
}
TEST_F(FalsePositiveRefutationBRVisitorTestBase,
UnSatAtErrorNodeDueToRefinedConstraintNoReport) {
constexpr auto Code = R"(
void reportIfCanBeTrue(bool);
void reachedWithNoContradiction();
void test(unsigned x, unsigned n) {
if (n >= 1 && n <= 2) {
if (x >= 3)
return;
// x: [0,2] and n: [1,2]
int y = x + n; // y: '(x+n)' Which is in approximately between 1 and 4.
// Registers the symbol 'y' with the constraint [1, MAX] in the true
// branch.
if (y > 0) {
// Since the x: [0,2] and n: [1,2], the 'y' is indeed greater than
// zero. If we emit a warning here, the constraints on the BugPath is
// SAT. Therefore that report is NOT invalidated.
reachedWithNoContradiction(); // 'y' can be greater than zero. OK
// If we ask the analyzer whether the 'y' can be 5. It won't know,
// therefore, the state will be created where the 'y' expression is 5.
// Although, this assumption is false!
// 'y' can not be 5 if the maximal value of both x and n is 2.
// The BugPath which become UnSAT in the ErrorNode with a refined
// constraint, should be invalidated.
reportIfCanBeTrue(y == 5);
}
}
})";
std::string Diags;
EXPECT_TRUE(runCheckerOnCodeWithArgs<addFalsePositiveGenerator>(
Code, LazyAssumeAndCrossCheckArgs, Diags));
EXPECT_EQ(Diags,
"test.FalsePositiveGenerator:REACHED_WITH_NO_CONTRADICTION\n");
// Single warning. The second report was invalidated by the visitor.
// Without enabling the crosscheck-with-z3 both reports are displayed.
std::string Diags2;
EXPECT_TRUE(runCheckerOnCodeWithArgs<addFalsePositiveGenerator>(
Code, LazyAssumeArgs, Diags2));
EXPECT_EQ(Diags2,
"test.FalsePositiveGenerator:REACHED_WITH_NO_CONTRADICTION\n"
"test.FalsePositiveGenerator:CAN_BE_TRUE\n");
}
} // namespace
} // namespace ento
} // namespace clang
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