llvm dev - Sep 2013 - [LLVMdev] initialization list with conversion operator dont work properly and report error

for the following code:

struct X
{
  X();
};

struct Y
{
  operator X() const;
};

X a = { Y() };    // reports error: no matching constructor for
initialization of 'X'
X aa = Y();  // works fine


clang when compiled with std=c++11 gives compilation errors as:


testfile.C:11:3: error: no matching constructor for initialization of
'X'
X a = { Y() };    // reports error: no matching constructor for
initialization of 'X'
  ^   ~~~~~~~
testfile.C:1:8: note: candidate constructor (the implicit copy constructor)
not viable: no known conversion from 'Y' to 'const X &' for
1st
      argument
struct X
       ^
testfile.C:1:8: note: candidate constructor (the implicit move constructor)
not viable: no known conversion from 'Y' to 'X &&' for
1st
      argument
struct X
       ^
testfile.C:3:3: note: candidate constructor not viable: requires 0
arguments, but 1 was provided
  X();
  ^
1 error generated.






-- 
Thanx & Regards
*Mayur Pandey *
+91-9742959541
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On Mon, Sep 23, 2013 at 11:43 PM, Mayur Pandey <mayurthebond at
gmail.com>wrote:
> for the following code:
>
> struct X
> {
>   X();
> };
>
> struct Y
> {
>   operator X() const;
> };
>
> X a = { Y() };    // reports error: no matching constructor for
> initialization of 'X'
> X aa = Y();  // works fine
>
>
> clang when compiled with std=c++11 gives compilation errors as:
>
>
> testfile.C:11:3: error: no matching constructor for initialization of
'X'
> X a = { Y() };    // reports error: no matching constructor for
> initialization of 'X'
>   ^   ~~~~~~~
> testfile.C:1:8: note: candidate constructor (the implicit copy
> constructor) not viable: no known conversion from 'Y' to 'const
X &' for 1st
>       argument
> struct X
>        ^
> testfile.C:1:8: note: candidate constructor (the implicit move
> constructor) not viable: no known conversion from 'Y' to 'X
&&' for 1st
>       argument
> struct X
>        ^
> testfile.C:3:3: note: candidate constructor not viable: requires 0
> arguments, but 1 was provided
>   X();
>   ^
> 1 error generated.
>
>
See C++11 [over.best.ics]p4.  We could probably improve the diagnostic
here, though; please file a bug.

-Eli
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Actually it should have not thrown error at all. it works fine with gcc.
And the part of code which you mentioned is not getting hit at all. Maybe
some difference in parsing is there.


On Wed, Sep 25, 2013 at 5:29 AM, Eli Friedman <eli.friedman at
gmail.com>wrote:
> On Mon, Sep 23, 2013 at 11:43 PM, Mayur Pandey <mayurthebond at
gmail.com>wrote:
>
>> for the following code:
>>
>> struct X
>> {
>>   X();
>> };
>>
>> struct Y
>> {
>>   operator X() const;
>> };
>>
>> X a = { Y() };    // reports error: no matching constructor for
>> initialization of 'X'
>> X aa = Y();  // works fine
>>
>>
>> clang when compiled with std=c++11 gives compilation errors as:
>>
>>
>> testfile.C:11:3: error: no matching constructor for initialization of
'X'
>> X a = { Y() };    // reports error: no matching constructor for
>> initialization of 'X'
>>   ^   ~~~~~~~
>> testfile.C:1:8: note: candidate constructor (the implicit copy
>> constructor) not viable: no known conversion from 'Y' to
'const X &' for 1st
>>       argument
>> struct X
>>        ^
>> testfile.C:1:8: note: candidate constructor (the implicit move
>> constructor) not viable: no known conversion from 'Y' to 'X
&&' for 1st
>>       argument
>> struct X
>>        ^
>> testfile.C:3:3: note: candidate constructor not viable: requires 0
>> arguments, but 1 was provided
>>   X();
>>   ^
>> 1 error generated.
>>
>>
> See C++11 [over.best.ics]p4.  We could probably improve the diagnostic
> here, though; please file a bug.
>
> -Eli
>


-- 
Thanx & Regards
*Mayur Pandey *
Senior Software Engineer
Samsung India Software Operations
Bangalore
+91-9742959541
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