[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

[Eli Friedman]

On Mon, Nov 7, 2011 at 5:52 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> 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.

Ah.

> 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).

Okay... not sure if I completely follow, but I'm sure you know what
you're doing. :)

-Eli