Extend the self-reference warning to catch when a constructor references itself upon initialization, such as using itself within its own copy constructor.

struct S {};
S s(s);

llvm-svn: 138969

clang/include/clang/Sema/Sema.h

@@ -1035,6 +1035,7 @@ public:
   bool SetParamDefaultArgument(ParmVarDecl *Param, Expr *DefaultArg,
                                SourceLocation EqualLoc);
 
+  void CheckSelfReference(Decl *OrigDecl, Expr *E);
   void AddInitializerToDecl(Decl *dcl, Expr *init, bool DirectInit,
                             bool TypeMayContainAuto);
   void ActOnUninitializedDecl(Decl *dcl, bool TypeMayContainAuto);

clang/lib/Sema/SemaDecl.cpp

@@ -5407,41 +5407,88 @@ namespace {
       : public EvaluatedExprVisitor<SelfReferenceChecker> {
     Sema &S;
     Decl *OrigDecl;
+    bool isRecordType;
+    bool isPODType;
 
   public:
     typedef EvaluatedExprVisitor<SelfReferenceChecker> Inherited;
 
     SelfReferenceChecker(Sema &S, Decl *OrigDecl) : Inherited(S.Context),
-                                                    S(S), OrigDecl(OrigDecl) { }
+                                                    S(S), OrigDecl(OrigDecl) {
+      isPODType = false;
+      isRecordType = false;
+      if (ValueDecl *VD = dyn_cast<ValueDecl>(OrigDecl)) {
+        isPODType = VD->getType().isPODType(S.Context);
+        isRecordType = VD->getType()->isRecordType();
+      }
+    }
 
     void VisitExpr(Expr *E) {
       if (isa<ObjCMessageExpr>(*E)) return;
+      if (isRecordType) {
+        Expr *expr = E;
+        if (MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
+          ValueDecl *VD = ME->getMemberDecl();
+          if (isa<EnumConstantDecl>(VD) || isa<VarDecl>(VD)) return;
+          expr = ME->getBase();
+        }
+        if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(expr)) {
+          HandleDeclRefExpr(DRE);
+          return;
+        }
+      }
       Inherited::VisitExpr(E);
     }
 
+    void VisitMemberExpr(MemberExpr *E) {
+      if (isa<FieldDecl>(E->getMemberDecl()))
+        if (DeclRefExpr *DRE
+              = dyn_cast<DeclRefExpr>(E->getBase()->IgnoreParenImpCasts())) {
+          HandleDeclRefExpr(DRE);
+          return;
+        }
+      Inherited::VisitMemberExpr(E);
+    }
+
     void VisitImplicitCastExpr(ImplicitCastExpr *E) {
-      CheckForSelfReference(E);
+      if ((!isRecordType &&E->getCastKind() == CK_LValueToRValue) ||
+          (isRecordType && E->getCastKind() == CK_NoOp)) {
+        Expr* SubExpr = E->getSubExpr()->IgnoreParenImpCasts();
+        if (MemberExpr *ME = dyn_cast<MemberExpr>(SubExpr))
+          SubExpr = ME->getBase()->IgnoreParenImpCasts();
+        if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(SubExpr)) {
+          HandleDeclRefExpr(DRE);
+          return;
+        }
+      }
       Inherited::VisitImplicitCastExpr(E);
     }
 
-    void CheckForSelfReference(ImplicitCastExpr *E) {
-      if (E->getCastKind() != CK_LValueToRValue) return;
-      Expr* SubExpr = E->getSubExpr()->IgnoreParenImpCasts();
-      DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(SubExpr);
-      if (!DRE) return;
+    void VisitUnaryOperator(UnaryOperator *E) {
+      // For POD record types, addresses of its own members are well-defined.
+      if (isRecordType && isPODType) return;
+      Inherited::VisitUnaryOperator(E);
+    } 
+    
+    void HandleDeclRefExpr(DeclRefExpr *DRE) {
       Decl* ReferenceDecl = DRE->getDecl(); 
       if (OrigDecl != ReferenceDecl) return;
       LookupResult Result(S, DRE->getNameInfo(), Sema::LookupOrdinaryName,
                           Sema::NotForRedeclaration);
-      S.DiagRuntimeBehavior(SubExpr->getLocStart(), SubExpr,
+      S.DiagRuntimeBehavior(DRE->getLocStart(), DRE,
                             S.PDiag(diag::warn_uninit_self_reference_in_init)
                               << Result.getLookupName()
                               << OrigDecl->getLocation()
-                              << SubExpr->getSourceRange());
+                              << DRE->getSourceRange());
     }
   };
 }
 
+/// CheckSelfReference - Warns if OrigDecl is used in expression E.
+void Sema::CheckSelfReference(Decl* OrigDecl, Expr *E) {
+  SelfReferenceChecker(*this, OrigDecl).VisitExpr(E);
+}
+
 /// AddInitializerToDecl - Adds the initializer Init to the
 /// declaration dcl. If DirectInit is true, this is C++ direct
 /// initialization rather than copy initialization.
@@ -5457,10 +5504,10 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
     // Variables declared within a function/method body are handled
     // by a dataflow analysis.
     if (!vd->hasLocalStorage() && !vd->isStaticLocal())
-      SelfReferenceChecker(*this, RealDecl).VisitExpr(Init);    
+      CheckSelfReference(RealDecl, Init);    
   }
   else {
-    SelfReferenceChecker(*this, RealDecl).VisitExpr(Init);
+    CheckSelfReference(RealDecl, Init);
   }
 
   if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(RealDecl)) {

clang/lib/Sema/SemaInit.cpp

@@ -3078,6 +3078,14 @@ static void TryConstructorInitialization(Sema &S,
                                          Expr **Args, unsigned NumArgs,
                                          QualType DestType,
                                          InitializationSequence &Sequence) {
+  // Check constructor arguments for self reference.
+  if (DeclaratorDecl *DD = Entity.getDecl())
+    // Parameters arguments are occassionially constructed with itself,
+    // for instance, in recursive functions.  Skip them.
+    if (!isa<ParmVarDecl>(DD))
+      for (unsigned i = 0; i < NumArgs; ++i)
+        S.CheckSelfReference(DD, Args[i]);
+
   // Build the candidate set directly in the initialization sequence
   // structure, so that it will persist if we fail.
   OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();

clang/test/SemaCXX/uninitialized.cpp

@@ -24,6 +24,78 @@ int i = boo(i);
 int j = far(j);
 int k = __alignof__(k);
 
+
+// Test self-references with record types.
+class A {
+  // Non-POD class.
+  public:
+    enum count { ONE, TWO, THREE };
+    int num;
+    static int count;
+    int get() const { return num; }
+    void set(int x) { num = x; }
+    static int zero() { return 0; }
+
+    A() {}
+    A(A const &a) {}
+    A(int x) {}
+    A(int *x) {}
+    A(A *a) {}
+};
+
+A getA() { return A(); }
+A getA(int x) { return A(); }
+A getA(A* a) { return A(); }
+
+void setupA() {
+  A a1;
+  a1.set(a1.get());
+  A a2(a1.get());
+  A a3(a1);
+  A a4(&a4);
+  A a5(a5.zero());
+  A a6(a6.ONE);
+  A a7 = getA();
+  A a8 = getA(a8.TWO);
+  A a9 = getA(&a9);
+  A a10(a10.count);
+
+  A a11(a11);  // expected-warning {{variable 'a11' is uninitialized when used within its own initialization}}
+  A a12(a12.get());  // expected-warning {{variable 'a12' is uninitialized when used within its own initialization}}
+  A a13(a13.num);  // expected-warning {{variable 'a13' is uninitialized when used within its own initialization}}
+  A a14 = A(a14);  // expected-warning {{variable 'a14' is uninitialized when used within its own initialization}}
+  A a15 = getA(a15.num);  // expected-warning {{variable 'a15' is uninitialized when used within its own initialization}}
+  A a16(&a16.num);  // expected-warning {{variable 'a16' is uninitialized when used within its own initialization}}
+}
+
+struct B {
+  // POD struct.
+  int x;
+  int *y;
+};
+
+B getB() { return B(); };
+B getB(int x) { return B(); };
+B getB(int *x) { return B(); };
+B getB(B *b) { return B(); };
+
+void setupB() {
+  B b1;
+  B b2(b1);
+  B b3 = { 5, &b3.x };
+  B b4 = getB();
+  B b5 = getB(&b5);
+  B b6 = getB(&b6.x);
+
+  // Silence unused warning
+  (void) b2;
+  (void) b4;
+
+  B b7(b7);  // expected-warning {{variable 'b7' is uninitialized when used within its own initialization}}
+  B b8 = getB(b8.x);  // expected-warning {{variable 'b8' is uninitialized when used within its own initialization}}
+  B b9 = getB(b9.y);  // expected-warning {{variable 'b9' is uninitialized when used within its own initialization}}
+}
+
 // Also test similar constructs in a field's initializer.
 struct S {
   int x;