[analyzer] Re-enable C++17-specific variable and member variable construction contexts.

[NoQ]

Summary

The recent refactoring allows us to easily support C++17 "copy-elided" constructor syntax for variables and constructor-initializers. Similar constructors for return values are still to be supported.

In particular, the change of using path-sensitive state traits made our liveness problems go away. The elision_on_ternary_op_branches test was failing without that.

D47350 allowed us to support the C++17 destructor in testCtorInitializer().

lib/StaticAnalyzer/Core/ExprEngineCXX.cpp

std::pair<ProgramStateRef, SVal> ExprEngine::prepareForObjectConstruction(
     const Expr *E, ProgramStateRef State, const LocationContext *LCtx,
     const ConstructionContext *CC, EvalCallOptions &CallOpts) {
   MemRegionManager &MRMgr = getSValBuilder().getRegionManager();
 
   // See if we're constructing an existing region by looking at the
   // current construction context.
   if (CC) {
     switch (CC->getKind()) {
+    case ConstructionContext::CXX17ElidedCopyVariableKind:
     case ConstructionContext::SimpleVariableKind: {
-      const auto *DSCC = cast<SimpleVariableConstructionContext>(CC);
+      const auto *DSCC = cast<VariableConstructionContext>(CC);
       const auto *DS = DSCC->getDeclStmt();
       const auto *Var = cast<VarDecl>(DS->getSingleDecl());
       SVal LValue = State->getLValue(Var, LCtx);
       QualType Ty = Var->getType();
       LValue =
           makeZeroElementRegion(State, LValue, Ty, CallOpts.IsArrayCtorOrDtor);
       State =
           addObjectUnderConstruction(State, DSCC->getDeclStmt(), LCtx, LValue);
       return std::make_pair(State, LValue);
     }
+    case ConstructionContext::CXX17ElidedCopyConstructorInitializerKind:
     case ConstructionContext::SimpleConstructorInitializerKind: {
       const auto *ICC = cast<ConstructorInitializerConstructionContext>(CC);
       const auto *Init = ICC->getCXXCtorInitializer();
       assert(Init->isAnyMemberInitializer());
       const CXXMethodDecl *CurCtor = cast<CXXMethodDecl>(LCtx->getDecl());
       Loc ThisPtr =
       getSValBuilder().getCXXThis(CurCtor, LCtx->getCurrentStackFrame());
       SVal ThisVal = State->getSVal(ThisPtr);
case ConstructionContext::TemporaryObjectKind: {
         State = addObjectUnderConstruction(State, BTE, LCtx, V);
 
       if (MTE)
         State = addObjectUnderConstruction(State, MTE, LCtx, V);
 
       CallOpts.IsTemporaryCtorOrDtor = true;
       return std::make_pair(State, V);
     }
-    case ConstructionContext::CXX17ElidedCopyVariableKind:
     case ConstructionContext::CXX17ElidedCopyReturnedValueKind:
-    case ConstructionContext::CXX17ElidedCopyConstructorInitializerKind:
       // Not implemented yet.
       break;
     }
   }
   // If we couldn't find an existing region to construct into, assume we're
   // constructing a temporary. Notify the caller of our failure.
   CallOpts.IsCtorOrDtorWithImproperlyModeledTargetRegion = true;
   return std::make_pair(

test/Analysis/cxx17-mandatory-elision.cpp

 #if __cplusplus >= 201703L
     // expected-warning@-2{{TRUE}}
 #else
     // expected-warning@-4{{UNKNOWN}}
 #endif
   }
 };
 
+
+struct A {
+  int x;
+  A(): x(0) {}
+  ~A() {}
+};
+
+struct B {
+  A a;
+  B() : a(A()) {}
+};
+
+void foo() {
+  B b;
+  clang_analyzer_eval(b.a.x == 0); // expected-warning{{TRUE}}
+}
+
 } // namespace ctor_initializer
 
 
+namespace elision_on_ternary_op_branches {
+class C1 {
+  int x;
+public:
+  C1(int x): x(x) {}
+  int getX() const { return x; }
+  ~C1();
+};
+
+class C2 {
+  int x;
+  int y;
+public:
+  C2(int x, int y): x(x), y(y) {}
+  int getX() const { return x; }
+  int getY() const { return y; }
+  ~C2();
+};
+
+void foo(int coin) {
+  C1 c1 = coin ? C1(1) : C1(2);
+  if (coin) {
+    clang_analyzer_eval(c1.getX() == 1); // expected-warning{{TRUE}}
+  } else {
+    clang_analyzer_eval(c1.getX() == 2); // expected-warning{{TRUE}}
+  }
+  C2 c2 = coin ? C2(3, 4) : C2(5, 6);
+  if (coin) {
+    clang_analyzer_eval(c2.getX() == 3); // expected-warning{{TRUE}}
+    clang_analyzer_eval(c2.getY() == 4); // expected-warning{{TRUE}}
+  } else {
+    clang_analyzer_eval(c2.getX() == 5); // expected-warning{{TRUE}}
+    clang_analyzer_eval(c2.getY() == 6); // expected-warning{{TRUE}}
+  }
+}
+} // namespace elision_on_ternary_op_branches
+
+
 namespace address_vector_tests {
 
 template <typename T> struct AddressVector {
   T *buf[10];
   int len;
 
   AddressVector() : len(0) {}
 
#else
   clang_analyzer_eval(v.buf[0] != v.buf[1]); // expected-warning{{TRUE}}
   clang_analyzer_eval(v.buf[1] != v.buf[2]); // expected-warning{{TRUE}}
   clang_analyzer_eval(v.buf[2] != v.buf[3]); // expected-warning{{TRUE}}
   clang_analyzer_eval(v.buf[3] != v.buf[4]); // expected-warning{{TRUE}}
   clang_analyzer_eval(v.buf[4] == &c); // expected-warning{{TRUE}}
 #endif
 }
 
+class ClassWithDestructor {
+  AddressVector<ClassWithDestructor> &v;
+
+public:
+  ClassWithDestructor(AddressVector<ClassWithDestructor> &v) : v(v) {
+    v.push(this);
+  }
+
+  ClassWithDestructor(ClassWithDestructor &&c) : v(c.v) { v.push(this); }
+  ClassWithDestructor(const ClassWithDestructor &c) : v(c.v) {
+    v.push(this);
+  }
+
+  ~ClassWithDestructor() { v.push(this); }
+};
+
+void testVariable() {
+  AddressVector<ClassWithDestructor> v;
+  {
+    ClassWithDestructor c = ClassWithDestructor(v);
+  }
+#if __cplusplus >= 201703L
+  // 0. Construct the variable.
+  // 1. Destroy the variable.
+  clang_analyzer_eval(v.len == 2); // expected-warning{{TRUE}}
+  clang_analyzer_eval(v.buf[0] == v.buf[1]); // expected-warning{{TRUE}}
+#else
+  // 0. Construct the temporary.
+  // 1. Construct the variable.
+  // 2. Destroy the temporary.
+  // 3. Destroy the variable.
+  clang_analyzer_eval(v.len == 4); // expected-warning{{TRUE}}
+  clang_analyzer_eval(v.buf[0] == v.buf[2]); // expected-warning{{TRUE}}
+  clang_analyzer_eval(v.buf[1] == v.buf[3]); // expected-warning{{TRUE}}
+#endif
+}
+
+struct TestCtorInitializer {
+  ClassWithDestructor c;
+  TestCtorInitializer(AddressVector<ClassWithDestructor> &v)
+    : c(ClassWithDestructor(v)) {}
+};
+
+void testCtorInitializer() {
+  AddressVector<ClassWithDestructor> v;
+  {
+    TestCtorInitializer t(v);
+  }
+#if __cplusplus >= 201703L
+  // 0. Construct the member variable.
+  // 1. Destroy the member variable.
+  clang_analyzer_eval(v.len == 2); // expected-warning{{TRUE}}
+  clang_analyzer_eval(v.buf[0] == v.buf[1]); // expected-warning{{TRUE}}
+#else
+  // 0. Construct the temporary.
+  // 1. Construct the member variable.
+  // 2. Destroy the temporary.
+  // 3. Destroy the member variable.
+  clang_analyzer_eval(v.len == 4); // expected-warning{{TRUE}}
+  clang_analyzer_eval(v.buf[0] == v.buf[2]); // expected-warning{{TRUE}}
+  clang_analyzer_eval(v.buf[1] == v.buf[3]); // expected-warning{{TRUE}}
+#endif
+}
+
 } // namespace address_vector_tests