[cfe-dev] Bug 18275 - Incorrect const qualifier behavior in definition.

[suyog sarda]

Ping !! Any help would be appreciated on this.

On Thu, Jan 30, 2014 at 1:04 AM, suyog sarda <sardask01 at gmail.com> wrote:

> Hi,
>
> I was looking at bug 18275 - Incorrect const qualifier behavior in
> definition.
>
> The declaration of A::f has a const. The definition doesn't.
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> *template <typename T>struct A {    void f(const int);};template <typename
> T>void A<T>::f(int x){    x = 0;}void f(){    A<float> a;    a.f(0);}*
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> Clang produces an error:
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> test.cpp:10:7: error: read-only variable is not assignable
>     x = 0;
>     ~ ^
> test.cpp:26:7: note: in instantiation of member function 'A<float>::f'
> requested here
>     a.f(0);
>       ^
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> It only happens for templateclasses. In exact the same situation with a
> regular class everything compiles well.
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> *struct B{    void f(const int);};void B::f(int x){    x = 0;} void
> f(){    B b;    b.f(0);}*GCC compiles both examples without an error.
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> According to my understanding, the standard 13.1/3 states that Parameter
> declarations that differ only in the presence or absence of const and/or
> volatile are equivalent. That is, the const and volatile type-specifiers
> for each parameter type are ignored when determining which function
> is being declared, defined, or called. So clang is wrong to throw error in
> template case.
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> After following the code path for above examples, i came across function
> name "*Sema::ActOnFunctionDeclarator*" in SemaDecl.cpp file, where
> everytime a function is redeclared/defined, its new declaration is created '
> *CreateNewFunctionDecl*', and its parameters are copied in following
> lines of code (l*ine number 6890 in SemaDecl.cpp in latest trunk version*)
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> *for (unsigned i = 0, e = FTI.NumArgs; i != e; ++i) {        ParmVarDecl
> *Param = cast<ParmVarDecl>(FTI.ArgInfo[i].Param);
> assert(Param->getDeclContext() != NewFD && "Was set before ?");
> Param->setDeclContext(NewFD);        Params.push_back(Param);*
> I couldn't find exactly where the codepath gets different for above two
> cases. For both TC above, parameters get copied in above lines of code. Can
> someone help in pointing out, where does the properties of function
> parameters/variables are set and where does those properties get reset on
> redeclaration/definition? Am i going wrong somewhere in above code analysis?
>
>
> --
> With regards,
> Suyog Sarda
>



-- 
With regards,
Suyog Sarda
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