[LLVMdev] [lld] -emit-yaml doesnot contain linker added symbols specified with command line options

[Shankar Easwaran]

Hi Nick,

On 8/28/2013 6:37 PM, Nick Kledzik wrote
> $cat 1.c
> int _start() { return 0; }
> $gcc -c 1.c
> $ld -u myundef 1.o
> ==> Does not throw any error, the resolver was hinted that myundef was a undefined weak symbol.
> Wow.  Reading the gnu ld man page, that is not obvious.  How can you make a non-weak undefined on the command line?  That is, how can you force and error if something is not defined?
I think the linker will barf only if the input file contained an 
undefined symbol and not by any other means.
>>>   Other options may need platform specific atoms which may be created with the help of static Writer methods.
>> We wouldnt be able to override the functionality with each flavor, if we have a static method, or you had thought of something else ?
> I’m not sure when we would want polymorphism.  If you wanted it in this case, there could be a method on LinkingContext to create a file of UndefinedAtoms, and ELFLinkingContext could override that method to make weak undefines.
Yes this will work for undefined atoms that need to be supported by all 
flavors. All the implicit files that are needed would be added to a 
vector of files in the inputGraph,
addImplicitFiles would splice/prepend to the list of input files which 
it already has.

Do you think that we still want the Writer::addFiles API, as this 
already covers the functionalities that is needed.

Thanks

Shankar Easwaran
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