Disallow catching exceptions by rvalue reference.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67492 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 30 insertions, 9 deletions

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index f4a8470ecb..51fb9829db 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1040,6 +1040,7 @@ def err_catch_incomplete_ptr : Error<
 def err_catch_incomplete_ref : Error<
   "cannot catch reference to incomplete type %0">;
 def err_catch_incomplete : Error<"cannot catch incomplete type %0">;
+def err_catch_rvalue_ref : Error<"cannot catch exceptions by rvalue reference">;
 def err_qualified_catch_declarator : Error<
   "exception declarator cannot be qualified">;
 def err_early_catch_all : Error<"catch-all handler must come last">;
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 95e282ae25..6be2052fdf 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -2320,6 +2320,11 @@ Sema::DeclTy *Sema::ActOnExceptionDeclarator(Scope *S, Declarator &D)
   // C++ 15.3p1: The exception-declaration shall not denote an incomplete type.
   // The exception-declaration shall not denote a pointer or reference to an
   // incomplete type, other than [cv] void*.
+  // N2844 forbids rvalue references.
+  if(ExDeclType->isRValueReferenceType()) {
+    Diag(Begin, diag::err_catch_rvalue_ref) << D.getSourceRange();
+    Invalid = true;
+  }
   QualType BaseType = ExDeclType;
   int Mode = 0; // 0 for direct type, 1 for pointer, 2 for reference
   unsigned DK = diag::err_catch_incomplete;
@@ -2328,16 +2333,15 @@ Sema::DeclTy *Sema::ActOnExceptionDeclarator(Scope *S, Declarator &D)
     Mode = 1;
     DK = diag::err_catch_incomplete_ptr;
   } else if(const ReferenceType *Ref = BaseType->getAsReferenceType()) {
+    // For the purpose of error recovery, we treat rvalue refs like lvalue refs.
     BaseType = Ref->getPointeeType();
     Mode = 2;
     DK = diag::err_catch_incomplete_ref;
   }
-  if ((Mode == 0 || !BaseType->isVoidType()) && 
+  if (!Invalid && (Mode == 0 || !BaseType->isVoidType()) &&
       RequireCompleteType(Begin, BaseType, DK))
     Invalid = true;
 
-  // FIXME: C++0x [except.handle] names the handler as cv T or cv T&, i.e.
-  // rvalue references aren't there. Oversight or intentional?
   // FIXME: Need to test for ability to copy-construct and destroy the
   // exception variable.
   // FIXME: Need to check for abstract classes.
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 5321935cfc..9f88a87474 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -1584,15 +1584,26 @@ Sema::CompareStandardConversionSequences(const StandardConversionSequence& SCS1,
         = CompareQualificationConversions(SCS1, SCS2))
     return QualCK;
 
-  // C++ [over.ics.rank]p3b4:
-  //   -- S1 and S2 are reference bindings (8.5.3), and the types to
-  //      which the references refer are the same type except for
-  //      top-level cv-qualifiers, and the type to which the reference
-  //      initialized by S2 refers is more cv-qualified than the type
-  //      to which the reference initialized by S1 refers.
   if (SCS1.ReferenceBinding && SCS2.ReferenceBinding) {
     QualType T1 = QualType::getFromOpaquePtr(SCS1.ToTypePtr);
     QualType T2 = QualType::getFromOpaquePtr(SCS2.ToTypePtr);
+    // C++0x [over.ics.rank]p3b4:
+    //   -- S1 and S2 are reference bindings (8.5.3) and neither refers to an
+    //      implicit object parameter of a non-static member function declared
+    //      without a ref-qualifier, and S1 binds an rvalue reference to an
+    //      rvalue and S2 binds an lvalue reference.
+    // FIXME: We have far too little information for this check. We don't know
+    // if the bound object is an rvalue. We don't know if the binding type is
+    // an rvalue or lvalue reference. We don't know if we're dealing with the
+    // implicit object parameter, or if the member function in this case has
+    // a ref qualifier.
+
+    // C++ [over.ics.rank]p3b4:
+    //   -- S1 and S2 are reference bindings (8.5.3), and the types to
+    //      which the references refer are the same type except for
+    //      top-level cv-qualifiers, and the type to which the reference
+    //      initialized by S2 refers is more cv-qualified than the type
+    //      to which the reference initialized by S1 refers.
     T1 = Context.getCanonicalType(T1);
     T2 = Context.getCanonicalType(T2);
     if (T1.getUnqualifiedType() == T2.getUnqualifiedType()) {
diff --git a/test/SemaCXX/rval-references.cpp b/test/SemaCXX/rval-references.cpp
index 59be9f50f6..df46814753 100644
--- a/test/SemaCXX/rval-references.cpp
+++ b/test/SemaCXX/rval-references.cpp
@@ -45,4 +45,9 @@ void f() {
   conv_to_not_int_rvalue cnir;
   not_int &&ni4 = cnir;
   not_int &ni5 = cnir; // expected-error{{non-const lvalue reference to type 'struct not_int' cannot be initialized with a value of type 'struct conv_to_not_int_rvalue'}}
+
+
+  try {
+  } catch(int&&) { // expected-error {{cannot catch exceptions by rvalue reference}}
+  }
 }