When declaring a catch block in C++, make sure that the type being

caught can be copy-initialized and destructed. Fixes PR6518.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97853 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDeclCXX.cpp

@@ -5212,14 +5212,35 @@ VarDecl *Sema::BuildExceptionDeclaration(Scope *S, QualType ExDeclType,
                              AbstractVariableType))
     Invalid = true;
 
-  // FIXME: Need to test for ability to copy-construct and destroy the
-  // exception variable.
-
-  // FIXME: Need to check for abstract classes.
-
   VarDecl *ExDecl = VarDecl::Create(Context, CurContext, Loc,
                                     Name, ExDeclType, TInfo, VarDecl::None);
 
+  if (!Invalid) {
+    if (const RecordType *RecordTy = ExDeclType->getAs<RecordType>()) {
+      // C++ [except.handle]p16:
+      //   The object declared in an exception-declaration or, if the 
+      //   exception-declaration does not specify a name, a temporary (12.2) is 
+      //   copy-initialized (8.5) from the exception object. [...]
+      //   The object is destroyed when the handler exits, after the destruction
+      //   of any automatic objects initialized within the handler.
+      //
+      // We just pretend to initialize the object with itself, then make sure 
+      // it can be destroyed later.
+      InitializedEntity Entity = InitializedEntity::InitializeVariable(ExDecl);
+      Expr *ExDeclRef = DeclRefExpr::Create(Context, 0, SourceRange(), ExDecl, 
+                                            Loc, ExDeclType, 0);
+      InitializationKind Kind = InitializationKind::CreateCopy(Loc, 
+                                                               SourceLocation());
+      InitializationSequence InitSeq(*this, Entity, Kind, &ExDeclRef, 1);
+      OwningExprResult Result = InitSeq.Perform(*this, Entity, Kind, 
+                                    MultiExprArg(*this, (void**)&ExDeclRef, 1));
+      if (Result.isInvalid())
+        Invalid = true;
+      else 
+        FinalizeVarWithDestructor(ExDecl, RecordTy);
+    }
+  }
+  
   if (Invalid)
     ExDecl->setInvalidDecl();
 

test/CXX/except/except.handle/p16.cpp

@@ -0,0 +1,40 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// The object declared in an exception-declaration or, if the
+// exception-declaration does not specify a name, a temporary (12.2)
+// is copy-initialized (8.5) from the exception object.
+//
+template<typename T>
+class X {
+  T* ptr;
+
+public:
+  X(const X<T> &) {
+    int *ip = 0;
+    ptr = ip; // expected-error{{incompatible type assigning 'int *', expected 'float *'}}
+  }
+
+  ~X() {
+    float *fp = 0;
+    ptr = fp; // expected-error{{incompatible type assigning 'float *', expected 'int *'}}
+  }
+};
+
+void f() {
+  try {
+  } catch (X<float>) { // expected-note{{instantiation}}
+    // copy constructor
+  } catch (X<int> xi) { // expected-note{{instantiation}}
+    // destructor
+  }
+}
+
+struct Abstract {
+  virtual void f() = 0; // expected-note{{pure virtual}}
+};
+
+void g() {
+  try {
+  } catch (Abstract) { // expected-error{{variable type 'Abstract' is an abstract class}}
+  }
+}