llvm-project/clang/test/Analysis/initializer.cpp
Devin Coughlin 412c0af2b8 [analyzer] Better detect when C++ object was constructed into existing region.
When the analyzer evaluates a CXXConstructExpr, it looks ahead in the CFG for
the current block to detect what region the object should be constructed into.
If the constructor was directly constructed into a local variable or field
region then there is no need to explicitly bind the constructed value to
the local or field when analyzing the DeclStmt or CXXCtorInitializer that
called the constructor.

Unfortunately, there were situations in which the CXXConstructExpr was
constructed into a temporary region but when evaluating the corresponding
DeclStmt or CXXCtorInitializer the analyzer assumed the object was constructed
into the local or field. This led to spurious warnings about uninitialized
values (PR25777).

To avoid these false positives, this commit factors out the logic for
determining when a CXXConstructExpr will be directly constructed into existing
storage, adds the inverse logic to detect when the corresponding later bind can
be safely skipped, and adds assertions to make sure these two checks are in
sync.

rdar://problem/21947725

llvm-svn: 255859
2015-12-17 00:28:33 +00:00

200 lines
4.3 KiB
C++

// RUN: %clang_cc1 -analyze -analyzer-checker=core,unix.Malloc,debug.ExprInspection -analyzer-config c++-inlining=constructors -std=c++11 -verify %s
void clang_analyzer_eval(bool);
class A {
int x;
public:
A();
};
A::A() : x(0) {
clang_analyzer_eval(x == 0); // expected-warning{{TRUE}}
}
class DirectMember {
int x;
public:
DirectMember(int value) : x(value) {}
int getX() { return x; }
};
void testDirectMember() {
DirectMember obj(3);
clang_analyzer_eval(obj.getX() == 3); // expected-warning{{TRUE}}
}
class IndirectMember {
struct {
int x;
};
public:
IndirectMember(int value) : x(value) {}
int getX() { return x; }
};
void testIndirectMember() {
IndirectMember obj(3);
clang_analyzer_eval(obj.getX() == 3); // expected-warning{{TRUE}}
}
struct DelegatingConstructor {
int x;
DelegatingConstructor(int y) { x = y; }
DelegatingConstructor() : DelegatingConstructor(42) {}
};
void testDelegatingConstructor() {
DelegatingConstructor obj;
clang_analyzer_eval(obj.x == 42); // expected-warning{{TRUE}}
}
struct RefWrapper {
RefWrapper(int *p) : x(*p) {}
RefWrapper(int &r) : x(r) {}
int &x;
};
void testReferenceMember() {
int *p = 0;
RefWrapper X(p); // expected-warning@-7 {{Dereference of null pointer}}
}
void testReferenceMember2() {
int *p = 0;
RefWrapper X(*p); // expected-warning {{Forming reference to null pointer}}
}
extern "C" char *strdup(const char *);
class StringWrapper {
char *str;
public:
StringWrapper(const char *input) : str(strdup(input)) {} // no-warning
};
// PR15070 - Constructing a type containing a non-POD array mistakenly
// tried to perform a bind instead of relying on the CXXConstructExpr,
// which caused a cast<> failure in RegionStore.
namespace DefaultConstructorWithCleanups {
class Element {
public:
int value;
class Helper {
public:
~Helper();
};
Element(Helper h = Helper());
};
class Wrapper {
public:
Element arr[2];
Wrapper();
};
Wrapper::Wrapper() /* initializers synthesized */ {}
int test() {
Wrapper w;
return w.arr[0].value; // no-warning
}
}
namespace DefaultMemberInitializers {
struct Wrapper {
int value = 42;
Wrapper() {}
Wrapper(int x) : value(x) {}
Wrapper(bool) {}
};
void test() {
Wrapper w1;
clang_analyzer_eval(w1.value == 42); // expected-warning{{TRUE}}
Wrapper w2(50);
clang_analyzer_eval(w2.value == 50); // expected-warning{{TRUE}}
Wrapper w3(false);
clang_analyzer_eval(w3.value == 42); // expected-warning{{TRUE}}
}
struct StringWrapper {
const char s[4] = "abc";
const char *p = "xyz";
StringWrapper(bool) {}
};
void testString() {
StringWrapper w(true);
clang_analyzer_eval(w.s[1] == 'b'); // expected-warning{{TRUE}}
clang_analyzer_eval(w.p[1] == 'y'); // expected-warning{{TRUE}}
}
}
namespace ReferenceInitialization {
struct OtherStruct {
OtherStruct(int i);
~OtherStruct();
};
struct MyStruct {
MyStruct(int i);
MyStruct(OtherStruct os);
void method() const;
};
void referenceInitializeLocal() {
const MyStruct &myStruct(5);
myStruct.method(); // no-warning
}
void referenceInitializeMultipleLocals() {
const MyStruct &myStruct1(5), myStruct2(5), &myStruct3(5);
myStruct1.method(); // no-warning
myStruct2.method(); // no-warning
myStruct3.method(); // no-warning
}
void referenceInitializeLocalWithCleanup() {
const MyStruct &myStruct(OtherStruct(5));
myStruct.method(); // no-warning
}
struct HasMyStruct {
const MyStruct &ms; // expected-note {{reference member declared here}}
const MyStruct &msWithCleanups; // expected-note {{reference member declared here}}
// clang's Sema issues a warning when binding a reference member to a
// temporary value.
HasMyStruct() : ms(5), msWithCleanups(OtherStruct(5)) {
// expected-warning@-1 {{binding reference member 'ms' to a temporary value}}
// expected-warning@-2 {{binding reference member 'msWithCleanups' to a temporary value}}
// At this point the members are not garbage so we should not expect an
// analyzer warning here even though binding a reference member
// to a member is a terrible idea.
ms.method(); // no-warning
msWithCleanups.method(); // no-warning
}
};
void referenceInitializeField() {
HasMyStruct hms;
}
};