[cfe-dev] Clang++ can't compile a simple hello world program.

[Eric Christopher]

On Sep 11, 2010, at 5:32 AM, Dimitry Andric wrote:

> On 2010-09-11 13:18, Anton Korobeynikov wrote:
>>> http://llvm.org/bugs/show_bug.cgi?id=7276#c3
>>> 
>>> I have no idea why this isn't committed yet...
>> Committed, thanks. For me it looks like slightly hacky, I don't pretty
>> much like OS checks in the driver.
>> Is it possible to move the check somewhere else? To some target-dependent part?
> 
> Probably, but this kind of stuff is done all over in Tools.cpp:
> 
>   // Enable -mconstructor-aliases except on darwin, where we have to
>   // work around a linker bug;  see <rdar://problem/7651567>.
>   if (getToolChain().getTriple().getOS() != llvm::Triple::Darwin)
>     CmdArgs.push_back("-mconstructor-aliases");
> 
> ...
> 
>   // -fms-extensions=0 is default.
>   if (Args.hasFlag(options::OPT_fms_extensions, options::OPT_fno_ms_extensions,
>                    getToolChain().getTriple().getOS() == llvm::Triple::Win32))
>     CmdArgs.push_back("-fms-extensions");
> 
> ...
> 
>   // -fnext-runtime defaults to on Darwin and when rewriting Objective-C, and is
>   // -the -cc1 default.
>   bool NeXTRuntimeIsDefault =
>     IsRewriter || getToolChain().getTriple().getOS() == llvm::Triple::Darwin;
>   if (!Args.hasFlag(options::OPT_fnext_runtime, options::OPT_fgnu_runtime,
>                     NeXTRuntimeIsDefault))
>     CmdArgs.push_back("-fgnu-runtime");
> 
> I think it falls under the category "ugly but necessary". :)

I don't think this is quite the best method for this one in particular since it largely depends on
the target OS, but this is a good workaround for now for sure.  I think, ideally, we're going to 
want triple based configuration inside the driver eventually that can do things like set options etc.

Thanks for looking into this!

-eric