[llvm] r221756 - Use a function_ref now that it works (r221753).

[Rafael Espíndola]

Oh, I see.

Would making just the member a std::function be correct? Would it be
profitable or are we better with just a std::function everywhere?

On 11 November 2014 21:28, David Blaikie <dblaikie at gmail.com> wrote:
>
>
> On Tue, Nov 11, 2014 at 6:23 PM, Rafael Espindola
> <rafael.espindola at gmail.com> wrote:
>>
>> Author: rafael
>> Date: Tue Nov 11 20:23:37 2014
>> New Revision: 221756
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=221756&view=rev
>> Log:
>> Use a function_ref now that it works (r221753).
>>
>>
>> Modified:
>>     llvm/trunk/include/llvm/Linker/Linker.h
>>
>> Modified: llvm/trunk/include/llvm/Linker/Linker.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Linker/Linker.h?rev=221756&r1=221755&r2=221756&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Linker/Linker.h (original)
>> +++ llvm/trunk/include/llvm/Linker/Linker.h Tue Nov 11 20:23:37 2014
>> @@ -11,8 +11,8 @@
>>  #define LLVM_LINKER_LINKER_H
>>
>>  #include "llvm/ADT/SmallPtrSet.h"
>> +#include "llvm/ADT/STLExtras.h"
>>
>> -#include <functional>
>>
>>  namespace llvm {
>>  class DiagnosticInfo;
>> @@ -25,7 +25,7 @@ class StructType;
>>  /// something with it after the linking.
>>  class Linker {
>>    public:
>> -    typedef std::function<void(const DiagnosticInfo &)>
>> +    typedef function_ref<void(const DiagnosticInfo &)>
>>          DiagnosticHandlerFunction;
>
>
> I think this usage is wrong, unfortunately.
>
> I haven't managed to look at all the Linker code, but at least looking at
> "Linker::Linker(Module *M)" this seems as if it'll have problems.
>
> That ctor initializes the member function_ref with a lambda. That' means the
> function_ref will point to the lambda (unlike std::function which would copy
> the lambda into itself) - but once the variable's initializer in the ctor
> finishes, the lambda will be destroyed, leaving the function_ref dangling, I
> think?
>
> Any other caller that does something like:
>
> Linken L([] { ... });
> L.functionThatUsesTheMemberFunctionRef();
>
> Will be equally problematic - as the lambda will be destroyed at the end of
> the Linker variable's initialization, and the member function_ref will be
> left dangling.
>
>>
>>
>>      Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler);
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: t.patch
Type: text/x-patch
Size: 1769 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20141111/8175a490/attachment.bin>