is "result" a reserved name ?

Code:

---

class foo
{
        int wesult;
        int result;

        template<class Pred>
        void call(Pred pred)
        {
                Pred();
        }

        void test()
        {
                call([&](){ wesult=1; result=1; });
        };
};

---

In the lamda function, I am apparently allowed to access/change a variable named wesult, but when I have a variable named result, I get a weird error:

Code:

---

1>c:\test\test.cpp(19): error C2326: 'void `anonymous-namespace'::<lambda0>::operator ()(void) const' : function cannot access 'foo::result'
1>c:\test\test.cpp(19): error C2166: l-value specifies const object

---

This is with VS2010.
Is 'result' a reserved keyword when used in combination with lambda's ? or is this some weird error ?

If I remove/comment out the result=1; then it compiles and runs normally.

Can anyone give this a try in VS2012 ?

Seems like an easy way to find out would be to call it something else and try again.

But he did - called it "wesult" and it worked...

indeed. it works if I rename "result" to anything I tried so far. So is this a bug, or is "result" something special in this case ? A new/planned keyword for which (partial ?) support is present already ?

According to the C++ Keywords result is not one.

in VS2010, with the exact code you posted I cannot reproduce the problem. It just gives me an error saying that Pred has no default ctor, as expected. Is that a typo ? anyway, replacing "Pred()" with "pred()" as it's probably meant to be, it just compiles fine ... :confused:

Quote:

---

Originally Posted by superbonzo

in VS2010, with the exact code you posted I cannot reproduce the problem. It just gives me an error saying that Pred has no default ctor, as expected. Is that a typo ? anyway, replacing "Pred()" with "pred()" as it's probably meant to be, it just compiles fine ... :confused:

---

I think that you actually need to use to function to generate the
compile error (after making test() public).

Code:

---


int main()
{
  foo fobj;
  fobj.test();
}

---

Reproduced with VS2010. No problem with VS 2012 RC.

However, I get a different result:

Quote:

---

1>vs2010_win32_test.cpp(54): error C2326: 'void `anonymous-namespace'::<lambda0>::operator ()(void) const' : function cannot access 'foo::result'
1>vs2010_win32_test.cpp(54): error C3491: '__this': a by-value capture cannot be modified in a non-mutable lambda

---

I guess C3491 is key here, because the following works correctly:

Code:

---

        void test()
        {
                call([=](){ this->result=1; });
        };

---

Notice that in VS2012 that is not necessary to specify = for capturing this by value, since this is always captured by value.

Quote:

---

Originally Posted by Philip Nicoletti

I think that you actually need to use to function to generate the
compile error (after making test() public).

---

no, foo is not a class template and test is an ordinary member function. The compiler is required to instantiate the call<> template when parsing the test() body, so no need to "use" the function. In any case, in my vs2010 copy the code:

Code:

---

class foo
{
        int wesult;
        int result;

        template<class Pred>
        void call(Pred pred)
        {
                pred();
        }
public:
        void test()
        {
                call([&]{ wesult=1; result=1; });
        };
};

int main()
{
  foo fobj;
  fobj.test();
}

---

compiles fine as well.

Strange ... the code you posted also compiles on my system.

My code was identical to yours, except I had an

Code:

---

#include <iostream>

---

at the top, which causes the compile error:

[quote]
1>Source1.cpp(16): error C2326: 'void `anonymous-namespace'::<lambda0>::operator ()(void) const' : function cannot access 'foo::result'
1>Source1.cpp(16): error C2166: l-value specifies const object
[/code]

16 .. is the "result = 1;" line

Quote:

---

Originally Posted by Philip Nicoletti

Strange ... the code you posted also compiles on my system. My code was identical to yours, except I had an

---

ok, for the sake of curiosity, I've traced back the problem into iostream; it's surely a compiler bug involving name lokup:

Code:

---

typedef int whatever;

class foo
{
        int whatever;

        template<class Pred>
        void call(Pred pred);

        void test() { call([this]{ whatever = 1; }); }
};

---

the above reproduces the error as well; note that if you place the typedef inside a struct you still get the same result ( this is what happens deep inside <iostream> ), in no way this can be legal. BTW, yet another workaround is to write foo::whatever ...

Took some digging further into this matter via Microsoft, and it is confirmed to be a name lookup issue in VS2010. The issue is apparently (but I can't test this atm) resolved in VS2012.

I've tested with VS2012 RC and is fixed indeed.