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[analyzer] MoveChecker: Improve warning and note messages. 

The warning piece traditionally describes the bug itself, i.e.
"The bug is a _____", eg. "Attempt to delete released memory",
"Resource leak", "Method call on a moved-from object".

Event pieces produced by the visitor are usually in a present tense, i.e.
"At this moment _____": "Memory is released", "File is closed",
"Object is moved".

Additionally, type information is added into the event pieces for STL objects
(in order to highlight that it is in fact an STL object), and the respective
event piece now mentions that the object is left in an unspecified state
after it was moved, which is a vital piece of information to understand the bug.

Differential Revision: https://reviews.llvm.org/D54560

llvm-svn: 348229
This commit is contained in:
Artem Dergachev 2018-12-04 02:00:29 +00:00
parent 5b8d585925
commit 60eb8c113b
2 changed files with 126 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
clang/lib/StaticAnalyzer/Checkers/MoveChecker.cpp
View File

@ -67,17 +67,29 @@ private:
bool STL : 1; // Is this an object of a standard type?
};
// Obtains ObjectKind of an object. Because class declaration cannot always
// be easily obtained from the memory region, it is supplied separately.
static ObjectKind classifyObject(const MemRegion *MR,
const CXXRecordDecl *RD);
// Classifies the object and dumps a user-friendly description string to
// the stream. Return value is equivalent to classifyObject.
static ObjectKind explainObject(llvm::raw_ostream &OS,
const MemRegion *MR, const CXXRecordDecl *RD);
class MovedBugVisitor : public BugReporterVisitor {
public:
MovedBugVisitor(const MemRegion *R) : Region(R), Found(false) {}
MovedBugVisitor(const MemRegion *R, const CXXRecordDecl *RD)
: Region(R), RD(RD), Found(false) {}
void Profile(llvm::FoldingSetNodeID &ID) const override {
static int X = 0;
ID.AddPointer(&X);
ID.AddPointer(Region);
// Don't add RD because it's, in theory, uniquely determined by
// the region. In practice though, it's not always possible to obtain
// the declaration directly from the region, that's why we store it
// in the first place.
}
std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *N,
@ -87,6 +99,8 @@ private:
private:
// The tracked region.
const MemRegion *Region;
// The class of the tracked object.
const CXXRecordDecl *RD;
bool Found;
};
@ -164,23 +178,21 @@ MoveChecker::MovedBugVisitor::VisitNode(const ExplodedNode *N,
return nullptr;
Found = true;
std::string ObjectName;
if (const auto DecReg =
unwrapRValueReferenceIndirection(Region)->getAs<DeclRegion>()) {
const auto *RegionDecl = dyn_cast<NamedDecl>(DecReg->getDecl());
ObjectName = RegionDecl->getNameAsString();
}
std::string InfoText;
if (ObjectName != "")
InfoText = "'" + ObjectName + "' became 'moved-from' here";
SmallString<128> Str;
llvm::raw_svector_ostream OS(Str);
OS << "Object";
ObjectKind OK = explainObject(OS, Region, RD);
if (OK.STL)
OS << " is left in a valid but unspecified state after move";
else
InfoText = "Became 'moved-from' here";
OS << " is moved";
// Generate the extra diagnostic.
PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
N->getLocationContext());
return std::make_shared<PathDiagnosticEventPiece>(Pos, InfoText, true);
}
return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true);
}
const ExplodedNode *MoveChecker::getMoveLocation(const ExplodedNode *N,
const MemRegion *Region,
@ -205,7 +217,7 @@ ExplodedNode *MoveChecker::reportBug(const MemRegion *Region,
MisuseKind MK) const {
if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
if (!BT)
BT.reset(new BugType(this, "Usage of a 'moved-from' object",
BT.reset(new BugType(this, "Use-after-move",
"C++ move semantics"));
// Uniqueing report to the same object.
@ -217,27 +229,29 @@ ExplodedNode *MoveChecker::reportBug(const MemRegion *Region,
MoveStmt, C.getSourceManager(), MoveNode->getLocationContext());
// Creating the error message.
std::string ErrorMessage;
llvm::SmallString<128> Str;
llvm::raw_svector_ostream OS(Str);
switch(MK) {
case MK_FunCall:
ErrorMessage = "Method call on a 'moved-from' object";
OS << "Method called on moved-from object";
explainObject(OS, Region, RD);
break;
case MK_Copy:
ErrorMessage = "Copying a 'moved-from' object";
OS << "Moved-from object";
explainObject(OS, Region, RD);
OS << " is copied";
break;
case MK_Move:
ErrorMessage = "Moving a 'moved-from' object";
OS << "Moved-from object";
explainObject(OS, Region, RD);
OS << " is moved";
break;
}
if (const auto DecReg = Region->getAs<DeclRegion>()) {
const auto *RegionDecl = dyn_cast<NamedDecl>(DecReg->getDecl());
ErrorMessage += " '" + RegionDecl->getNameAsString() + "'";
}
auto R =
llvm::make_unique<BugReport>(*BT, ErrorMessage, N, LocUsedForUniqueing,
llvm::make_unique<BugReport>(*BT, OS.str(), N, LocUsedForUniqueing,
MoveNode->getLocationContext()->getDecl());
R->addVisitor(llvm::make_unique<MovedBugVisitor>(Region));
R->addVisitor(llvm::make_unique<MovedBugVisitor>(Region, RD));
C.emitReport(std::move(R));
return N;
}
@ -364,6 +378,23 @@ MoveChecker::ObjectKind MoveChecker::classifyObject(const MemRegion *MR,
};
}
MoveChecker::ObjectKind MoveChecker::explainObject(llvm::raw_ostream &OS,
const MemRegion *MR,
const CXXRecordDecl *RD) {
// We may need a leading space every time we actually explain anything,
// and we never know if we are to explain anything until we try.
if (const auto DR =
dyn_cast_or_null<DeclRegion>(unwrapRValueReferenceIndirection(MR))) {
const auto *RegionDecl = cast<NamedDecl>(DR->getDecl());
OS << " '" << RegionDecl->getNameAsString() << "'";
}
ObjectKind OK = classifyObject(MR, RD);
if (OK.STL) {
OS << " of type '" << RD->getQualifiedNameAsString() << "'";
}
return OK;
}
void MoveChecker::checkPreCall(const CallEvent &Call, CheckerContext &C) const {
ProgramStateRef State = C.getState();
const LocationContext *LC = C.getLocationContext();

142
clang/test/Analysis/use-after-move.cpp
View File

@ -88,7 +88,7 @@ public:
A(const A &other) : i(other.i), d(other.d), b(other.b) {}
A(A &&other) : i(other.i), d(other.d), b(std::move(other.b)) {
#ifdef AGGRESSIVE
// expected-note@-2{{'b' became 'moved-from' here}}
// expected-note@-2{{Object 'b' is moved}}
#endif
}
A(A &&other, char *k) {
@ -137,18 +137,18 @@ void copyOrMoveCall(A a) {
void simpleMoveCtorTest() {
{
A a;
A b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
A b = std::move(a); // expected-note {{Object 'a' is moved}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
{
A a;
A b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
b = a; // expected-warning {{Copying a 'moved-from' object 'a'}} expected-note {{Copying a 'moved-from' object 'a'}}
A b = std::move(a); // expected-note {{Object 'a' is moved}}
b = a; // expected-warning {{Moved-from object 'a' is copied}} expected-note {{Moved-from object 'a' is copied}}
}
{
A a;
A b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
b = std::move(a); // expected-warning {{Moving a 'moved-from' object 'a'}} expected-note {{Moving a 'moved-from' object 'a'}}
A b = std::move(a); // expected-note {{Object 'a' is moved}}
b = std::move(a); // expected-warning {{Moved-from object 'a' is moved}} expected-note {{Moved-from object 'a' is moved}}
}
}
@ -156,20 +156,20 @@ void simpleMoveAssignementTest() {
{
A a;
A b;
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
{
A a;
A b;
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
A c(a); // expected-warning {{Copying a 'moved-from' object 'a'}} expected-note {{Copying a 'moved-from' object 'a'}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
A c(a); // expected-warning {{Moved-from object 'a' is copied}} expected-note {{Moved-from object 'a' is copied}}
}
{
A a;
A b;
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
A c(std::move(a)); // expected-warning {{Moving a 'moved-from' object 'a'}} expected-note {{Moving a 'moved-from' object 'a'}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
A c(std::move(a)); // expected-warning {{Moved-from object 'a' is moved}} expected-note {{Moved-from object 'a' is moved}}
}
}
@ -178,8 +178,8 @@ void moveInInitListTest() {
A a;
};
A a;
S s{std::move(a)}; // expected-note {{'a' became 'moved-from' here}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
S s{std::move(a)}; // expected-note {{Object 'a' is moved}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
// Don't report a bug if the variable was assigned to in the meantime.
@ -227,19 +227,19 @@ void reinitializationTest(int i) {
A b;
b = std::move(a);
a = A();
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
// If a path exist where we not reinitialize the variable we report a bug.
{
A a;
A b;
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
if (i < 10) { // expected-note {{Assuming 'i' is >= 10}} expected-note {{Taking false branch}}
a = A();
}
if (i > 5) { // expected-note {{Taking true branch}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
}
}
@ -325,8 +325,8 @@ void loopTest() {
{
A a;
for (int i = 0; i < bignum(); i++) { // expected-note {{Loop condition is true. Entering loop body}} expected-note {{Loop condition is true. Entering loop body}}
constCopyOrMoveCall(std::move(a)); // expected-warning {{Moving a 'moved-from' object 'a'}} expected-note {{Moving a 'moved-from' object 'a'}}
// expected-note@-1 {{'a' became 'moved-from' here}}
constCopyOrMoveCall(std::move(a)); // expected-warning {{Moved-from object 'a' is moved}} expected-note {{Moved-from object 'a' is moved}}
// expected-note@-1 {{Object 'a' is moved}}
}
}
@ -348,10 +348,10 @@ void loopTest() {
void uniqueTest(bool cond) {
A a(42, 42.0);
A b;
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
if (cond) { // expected-note {{Assuming 'cond' is not equal to 0}} expected-note {{Taking true branch}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
if (cond) {
a.bar(); // no-warning
@ -362,8 +362,8 @@ void uniqueTest(bool cond) {
void uniqueTest2() {
A a;
A a1 = std::move(a); // expected-note {{'a' became 'moved-from' here}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
A a1 = std::move(a); // expected-note {{Object 'a' is moved}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
A a2 = std::move(a); // no-warning
a.foo(); // no-warning
@ -373,12 +373,12 @@ void uniqueTest2() {
//even on moved-from objects.
void moveSafeFunctionsTest() {
A a;
A b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
A b = std::move(a); // expected-note {{Object 'a' is moved}}
a.empty(); // no-warning
a.isEmpty(); // no-warning
(void)a; // no-warning
(bool)a; // expected-warning {{expression result unused}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
void moveStateResetFunctionsTest() {
@ -445,17 +445,17 @@ class memberVariablesTest {
b = std::move(a);
a.foo();
#ifdef AGGRESSIVE
// expected-note@-3{{'a' became 'moved-from' here}}
// expected-warning@-3 {{Method call on a 'moved-from' object 'a'}}
// expected-note@-4{{Method call on a 'moved-from' object 'a'}}
// expected-note@-3{{Object 'a' is moved}}
// expected-warning@-3 {{Method called on moved-from object 'a'}}
// expected-note@-4{{Method called on moved-from object 'a'}}
#endif
b = std::move(static_a);
static_a.foo();
#ifdef AGGRESSIVE
// expected-note@-3{{'static_a' became 'moved-from' here}}
// expected-warning@-3{{Method call on a 'moved-from' object 'static_a'}}
// expected-note@-4{{Method call on a 'moved-from' object 'static_a'}}
// expected-note@-3{{Object 'static_a' is moved}}
// expected-warning@-3{{Method called on moved-from object 'static_a'}}
// expected-note@-4{{Method called on moved-from object 'static_a'}}
#endif
}
};
@ -466,26 +466,26 @@ void PtrAndArrayTest() {
Arr[2] = std::move(*Ptr);
(*Ptr).foo();
#ifdef AGGRESSIVE
// expected-note@-3{{Became 'moved-from' here}}
// expected-warning@-3{{Method call on a 'moved-from' object}}
// expected-note@-4{{Method call on a 'moved-from' object}}
// expected-note@-3{{Object is moved}}
// expected-warning@-3{{Method called on moved-from object}}
// expected-note@-4{{Method called on moved-from object}}
#endif
Ptr = &Arr[1];
Arr[3] = std::move(Arr[1]);
Ptr->foo();
#ifdef AGGRESSIVE
// expected-note@-3{{Became 'moved-from' here}}
// expected-warning@-3{{Method call on a 'moved-from' object}}
// expected-note@-4{{Method call on a 'moved-from' object}}
// expected-note@-3{{Object is moved}}
// expected-warning@-3{{Method called on moved-from object}}
// expected-note@-4{{Method called on moved-from object}}
#endif
Arr[3] = std::move(Arr[2]);
Arr[2].foo();
#ifdef AGGRESSIVE
// expected-note@-3{{Became 'moved-from' here}}
// expected-warning@-3{{Method call on a 'moved-from' object}}
// expected-note@-4{{Method call on a 'moved-from' object}}
// expected-note@-3{{Object is moved}}
// expected-warning@-3{{Method called on moved-from object}}
// expected-note@-4{{Method called on moved-from object}}
#endif
Arr[2] = std::move(Arr[3]); // reinitialization
@ -545,9 +545,9 @@ void differentBranchesTest(int i) {
A a, b;
switch (i) { // expected-note {{Control jumps to 'case 1:'}}
case 1:
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
case 2:
a.foo(); // expected-warning {{Method call on a 'moved-from' object}} expected-note {{Method call on a 'moved-from' object 'a'}}
a.foo(); // expected-warning {{Method called on moved-from object}} expected-note {{Method called on moved-from object 'a'}}
break;
}
}
@ -562,13 +562,13 @@ void tempTest() {
}
void interFunTest1(A &a) {
a.bar(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
a.bar(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
}
void interFunTest2() {
A a;
A b;
b = std::move(a); // expected-note {{'a' became 'moved-from' here}}
b = std::move(a); // expected-note {{Object 'a' is moved}}
interFunTest1(a); // expected-note {{Calling 'interFunTest1'}}
}
@ -577,8 +577,8 @@ void foobar(int i, A a);
void paramEvaluateOrderTest() {
A a;
foobar(std::move(a), a.getI()); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
// expected-note@-1 {{'a' became 'moved-from' here}}
foobar(std::move(a), a.getI()); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
// expected-note@-1 {{Object 'a' is moved}}
//FALSE NEGATIVE since parameters evaluate order is undefined
foobar(a.getI(), std::move(a)); //no-warning
@ -613,8 +613,8 @@ void declarationSequenceTest() {
}
{
A a;
A a1 = std::move(a), a2 = a; // expected-warning {{Copying a 'moved-from' object 'a'}} expected-note {{Copying a 'moved-from' object 'a'}}
// expected-note@-1 {{'a' became 'moved-from' here}}
A a1 = std::move(a), a2 = a; // expected-warning {{Moved-from object 'a' is copied}} expected-note {{Moved-from object 'a' is copied}}
// expected-note@-1 {{Object 'a' is moved}}
}
}
@ -640,8 +640,8 @@ void logicalOperatorsSequenceTest() {
}
{
A a;
if (A(std::move(a)).foo() > 0 && a.foo() > 0) { // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
// expected-note@-1 {{'a' became 'moved-from' here}} expected-note@-1 {{Assuming the condition is true}} expected-note@-1 {{Assuming the condition is false}}
if (A(std::move(a)).foo() > 0 && a.foo() > 0) { // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
// expected-note@-1 {{Object 'a' is moved}} expected-note@-1 {{Assuming the condition is true}} expected-note@-1 {{Assuming the condition is false}}
// expected-note@-2 {{Left side of '&&' is false}} expected-note@-2 {{Left side of '&&' is true}}
// expected-note@-3 {{Taking false branch}}
A().bar();
@ -657,8 +657,8 @@ void logicalOperatorsSequenceTest() {
}
{
A a;
if (A(std::move(a)).foo() > 0 || a.foo() > 0) { // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
// expected-note@-1 {{'a' became 'moved-from' here}} expected-note@-1 {{Assuming the condition is false}} expected-note@-1 {{Left side of '||' is false}}
if (A(std::move(a)).foo() > 0 || a.foo() > 0) { // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
// expected-note@-1 {{Object 'a' is moved}} expected-note@-1 {{Assuming the condition is false}} expected-note@-1 {{Left side of '||' is false}}
A().bar();
}
}
@ -695,9 +695,9 @@ void subRegionMoveTest() {
B b = std::move(a.b);
a.b.foo();
#ifdef AGGRESSIVE
// expected-note@-3{{'b' became 'moved-from' here}}
// expected-warning@-3{{Method call on a 'moved-from' object 'b'}}
// expected-note@-4 {{Method call on a 'moved-from' object 'b'}}
// expected-note@-3{{Object 'b' is moved}}
// expected-warning@-3{{Method called on moved-from object 'b'}}
// expected-note@-4 {{Method called on moved-from object 'b'}}
#endif
}
{
@ -707,21 +707,21 @@ void subRegionMoveTest() {
#ifdef AGGRESSIVE
// expected-note@-3{{Calling move constructor for 'A'}}
// expected-note@-4{{Returning from move constructor for 'A'}}
// expected-warning@-4{{Method call on a 'moved-from' object 'b'}}
// expected-note@-5{{Method call on a 'moved-from' object 'b'}}
// expected-warning@-4{{Method called on moved-from object 'b'}}
// expected-note@-5{{Method called on moved-from object 'b'}}
#endif
}
// Don't report a misuse if any SuperRegion is already reported.
{
A a;
A a1 = std::move(a); // expected-note {{'a' became 'moved-from' here}}
a.foo(); // expected-warning {{Method call on a 'moved-from' object 'a'}} expected-note {{Method call on a 'moved-from' object 'a'}}
A a1 = std::move(a); // expected-note {{Object 'a' is moved}}
a.foo(); // expected-warning {{Method called on moved-from object 'a'}} expected-note {{Method called on moved-from object 'a'}}
a.b.foo(); // no-warning
}
{
C c;
C c1 = std::move(c); // expected-note {{'c' became 'moved-from' here}}
c.foo(); // expected-warning {{Method call on a 'moved-from' object 'c'}} expected-note {{Method call on a 'moved-from' object 'c'}}
C c1 = std::move(c); // expected-note {{Object 'c' is moved}}
c.foo(); // expected-warning {{Method called on moved-from object 'c'}} expected-note {{Method called on moved-from object 'c'}}
c.b.foo(); // no-warning
}
}
@ -742,8 +742,8 @@ void resetSuperClass2() {
void reportSuperClass() {
C c;
C c1 = std::move(c); // expected-note {{'c' became 'moved-from' here}}
c.foo(); // expected-warning {{Method call on a 'moved-from' object 'c'}} expected-note {{Method call on a 'moved-from' object 'c'}}
C c1 = std::move(c); // expected-note {{Object 'c' is moved}}
c.foo(); // expected-warning {{Method called on moved-from object 'c'}} expected-note {{Method called on moved-from object 'c'}}
C c2 = c; // no-warning
}
@ -786,14 +786,14 @@ class HasSTLField {
void foo() {
// Warn even in non-aggressive mode when it comes to STL, because
// in STL the object is left in "valid but unspecified state" after move.
std::vector<int> W = std::move(V); // expected-note{{'V' became 'moved-from' here}}
V.push_back(123); // expected-warning{{Method call on a 'moved-from' object 'V'}}
// expected-note@-1{{Method call on a 'moved-from' object 'V'}}
std::vector<int> W = std::move(V); // expected-note{{Object 'V' of type 'std::vector' is left in a valid but unspecified state after move}}
V.push_back(123); // expected-warning{{Method called on moved-from object 'V'}}
// expected-note@-1{{Method called on moved-from object 'V'}}
}
};
void localRValueMove(A &&a) {
A b = std::move(a); // expected-note{{'a' became 'moved-from' here}}
a.foo(); // expected-warning{{Method call on a 'moved-from' object}}
// expected-note@-1{{Method call on a 'moved-from' object}}
A b = std::move(a); // expected-note{{Object 'a' is moved}}
a.foo(); // expected-warning{{Method called on moved-from object 'a'}}
// expected-note@-1{{Method called on moved-from object 'a'}}
}