[cfe-commits] r144056 - in /cfe/trunk: lib/AST/Expr.cpp lib/AST/ExprConstant.cpp test/SemaCXX/constant-expression-cxx11.cpp test/SemaCXX/constant-expression.cpp

[Richard Smith]

On Tue, November 8, 2011 01:41, Eli Friedman wrote:
> On Mon, Nov 7, 2011 at 5:31 PM, Richard Smith
> <richard-llvm at metafoo.co.uk> wrote:
>
>> Author: rsmith
>> Date: Mon Nov  7 19:31:09 2011
>> New Revision: 144056
>>
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=144056&view=rev
>> Log:
>> Fix a cluster of related issues involving value-dependence and constant
>> expression evaluation:  - When folding a non-value-dependent expression, we
>> may try to use the   initializer of a value-dependent variable. If that
>> happens, give up.  - In C++98, actually check that a const, non-volatile
>> DeclRefExpr inside an ICE
>>   is of integral or enumeration type (a reference isn't OK!)
>>  - In C++11, DeclRefExprs for objects of const literal type initialized with
>>    value-dependent expressions are themselves value-dependent.
>>  - So are references initialized with value-dependent expressions (though
>> this   case is missing from the C++11 standard, along with many others).
>>
>>
>> Modified:
>>    cfe/trunk/lib/AST/Expr.cpp
>>    cfe/trunk/lib/AST/ExprConstant.cpp
>>    cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
>>    cfe/trunk/test/SemaCXX/constant-expression.cpp
>>
>>
>> Modified: cfe/trunk/lib/AST/Expr.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=144056&r
>> 1=144055&r2=144056&view=diff
>> ============================================================================
>> ==
>> --- cfe/trunk/lib/AST/Expr.cpp (original)
>> +++ cfe/trunk/lib/AST/Expr.cpp Mon Nov  7 19:31:09 2011
>> @@ -185,21 +185,29 @@
>>
>>
>>   //  (VD) - a constant with integral or enumeration type and is
>>   //         initialized with an expression that is value-dependent.
>> +  //  (VD) - a constant with literal type and is initialized with an
>> +  //         expression that is value-dependent [C++11].
>> +  //  (VD) - FIXME: Missing from the standard:
>> +  //       -  an entity with reference type and is initialized with an
>> +  //          expression that is value-dependent [C++11]
>>   if (VarDecl *Var = dyn_cast<VarDecl>(D)) {
>> -    if (Var->getType()->isIntegralOrEnumerationType() &&
>> -        Var->getType().getCVRQualifiers() == Qualifiers::Const) {
>> +    if ((D->getASTContext().getLangOptions().CPlusPlus0x ?
>> +           Var->getType()->isLiteralType() :
>> +           Var->getType()->isIntegralOrEnumerationType()) &&
>> +        (Var->getType().getCVRQualifiers() == Qualifiers::Const ||
>> +         Var->getType()->isReferenceType())) {
>>       if (const Expr *Init = Var->getAnyInitializer())
>>         if (Init->isValueDependent()) {
>>           ValueDependent = true;
>>           InstantiationDependent = true;
>>         }
>> -    }
>> -
>> +    }
>> +
>>     // (VD) - FIXME: Missing from the standard:
>>     //      -  a member function or a static data member of the current
>>     //         instantiation
>> -    else if (Var->isStaticDataMember() &&
>> -             Var->getDeclContext()->isDependentContext()) {
>> +    if (Var->isStaticDataMember() &&
>> +        Var->getDeclContext()->isDependentContext()) {
>>       ValueDependent = true;
>>       InstantiationDependent = true;
>>     }
>> @@ -213,8 +221,7 @@
>>   if (isa<CXXMethodDecl>(D) && D->getDeclContext()->isDependentContext()) {
>>     ValueDependent = true;
>>     InstantiationDependent = true;
>> -    return;
>> -  }
>> +  }
>>  }
>>
>>
>>  void DeclRefExpr::computeDependence() {
>>
>>
>> Modified: cfe/trunk/lib/AST/ExprConstant.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=
>> 144056&r1=144055&r2=144056&view=diff
>> ============================================================================
>> ==
>> --- cfe/trunk/lib/AST/ExprConstant.cpp (original)
>> +++ cfe/trunk/lib/AST/ExprConstant.cpp Mon Nov  7 19:31:09 2011
>> @@ -552,7 +552,7 @@
>>     return false;
>>
>>
>>   const Expr *Init = VD->getAnyInitializer();
>> -  if (!Init)
>> +  if (!Init || Init->isValueDependent())
>>     return false;
>>
>
> Is this check actually necessary?  We shouldn't be querying ICEness on
> a value-dependent expression.

Yes. This isn't in the ICE check, this is when folding a VarDecl's
initializer. An expression can contain a DeclRefExpr for a VarDecl with a
value-dependent initializer without itself being value-dependent (and, for
instance, we support folding the initializers of const doubles in C++98, but
such DeclRefExprs aren't value-dependent according to the C++98 standard).

Richard