[PATCH] Make the driver accept all four variants of the target option

[Renato Golin]

In http://reviews.llvm.org/D7730#126353, @richard.barton.arm wrote:

> Point taken, but there are counterexamples. A very quick play in my terminal shows that diff accepts the option --ifdef with either a space or = separating the argument. Same for grep and --exclude, emacs and --cursor-color.


If the others are not following the "standard", let's not break what is.

> -mcpu=, -fdiagnostics-color= are both valid.


These are GCC's fault, there isn't much we can do.

> --mhwdiv is available as --mhwdiv=arm, --mhwdiv arm and -mhwdiv=arm, but not as -mhwdiv arm!


I'd remove the non-conforming options. How does GCC behave in those cases?

> "Need" is too strong here. Our concern is out-of-box usability to people unfamiliar with the tool. If a user takes clang and passes --target arm-none-eabi or -target=arm-none-eabi they get error messages like:

> 

> clang-3.7: error: unsupported option '--target'

>  clang-3.7: error: no such file or directory: 'arm-none-eabi'

> 

> or

> 

> clang-3.7: error: unknown argument: '-target=arm-none-eabi'

> 

> which is pretty poor.


I agree, but we should fix the error messages, and not add more complexity. We already have infrastructure in Clang to suggest the appropriate syntax, we should use that instead.

> It seems to me that given clang is not consistent with its application of these unix rules and that there are no gcc compatibility issues to consider, this would be a simple way to improve the situation.


We don't "have" to be consistent to anything, we just *want* to be. The ones we chose to follow on Unix systems are the Unix and GCC standards, where it fits. My view is that everything else that is neither, should fit into one or the other.

I certainly don't speak for everyone, but for this specific case, I think we should fix the diagnostics on -target, instead of accepting more options.

cheers,
--renato


REPOSITORY
  rL LLVM

http://reviews.llvm.org/D7730

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/