Implement flexible target specification

[emberian]

See commit message.

[emberian]

Still trying to figure out a bug where executables aren't getting the executable bit set...

[emberian]

Seems to have resolved itself with a rebase ¯_(ツ)_/¯

[huonw]

Who installs to /etc/rustc?

[alexcrichton]

This feature may want to remain unimplemented for now due to some open questions here, but it probably doesn't matter too much.

[huonw]

Can you write a run-make test that checks the compiler is correctly searching for, parsing and using external specifications? (E.g. it could run rustc --target=foo-bar-baz --emit=asm ... with a custom target that disables stack checks, and then grep for stack checks.)

[emberian]

Another issue: probably needs to allow specifying target_os instead of taking it from the target triple. I'm not actually sure this is a good idea, though, and it seems MUCH more clear that the target_os comes from the triple name itself. But we'd need to rename "osx" to "darwin", which I feel is almost a lie? Not really sure. Need feedback.

[emberian]

(The RFC specifies taking it from the target)

[emberian]

@huonw how do those docs look?

[emberian]

Hm, glaringly obvious problem: linker should probably include a target triple prefix, for cross compiling. ie, x86_64-unknown-linux-gnu-cc.

[errordeveloper]

@farcaller we should try this with arm-none-eabi

[emberian]

Be warned that this isn't quite working yet. My current status is:

LLVM ERROR: not a number, or does not fit in an unsigned int

[emberian]

(Already fixed I think, still building..)

[huonw]

Do we have a story for interacting with cargo?

[emberian]

Not yet, no.

[mneumann]

When compiling this on DragonFly I run into these problems:

/home/mneumann/rust/src/liblibc/lib.rs:2943:47: 2943:53 error: unresolved import
`types::os::arch::c95::c_uint`. Could not find `arch` in `types::os`.
/home/mneumann/rust/src/liblibc/lib.rs:2943 use types::os::arch::c95
::{c_int, c_uint};
^~~~~~
/home/mneumann/rust/src/liblibc/lib.rs:2965:17: 2965:44 error: unresolved import
`types::os::arch::c95::c_int`. Could not find `arch` in `types::os`.
/home/mneumann/rust/src/liblibc/lib.rs:2965 use types::os::arch::c95
::c_int;
^~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/mneumann/rust/src/liblibc/lib.rs:2966:17: 2966:49 error: unresolved import
`types::os::arch::posix88::mode_t`. Could not find `arch` in `types::os`.
/home/mneumann/rust/src/liblibc/lib.rs:2966 use types::os::arch::pos
ix88::mode_t;
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/mneumann/rust/src/liblibc/lib.rs:3209:17: 3209:44 error: unresolved import
`types::os::arch::c95::c_int`. Could not find `arch` in `types::os`.
/home/mneumann/rust/src/liblibc/lib.rs:3209 use types::os::arch::c95
::c_int;
^~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/mneumann/rust/src/liblibc/lib.rs:150:54: 150:58 error: unresolved import (
maybe you meant `stat::*`?)
/home/mneumann/rust/src/liblibc/lib.rs:150 pub use funcs::posix88::stat_::{chmod
, fstat, mkdir, stat};
^~~~
error: aborting due to 115 previous errors
gmake: *** [x86_64-unknown-dragonfly/stage1/lib/rustlib/x86_64-unknown-dragonfly
/lib/stamp.libc] Error 101

Maybe the target_os is incorrectly determined?

[alexcrichton]

false => true ?

[alexcrichton]

Ah nevermind, it would be nice to preserve the comments in the source code to this target specification about why this is false

[vadimcn]

Rebased, fixed, squashed: https://github.com/vadimcn/rust/tree/flextarget. Passes tests on Windows.
@cmr: Do you want me to submit it?

[aturon]

Revived, yay!

[klutzy]

- $gnu_t=$(to_gnu_triple $t)+ gnu_t=$(to_gnu_triple $t)

[vadimcn]

Yup, @klutzy is absolutely right! I guess this doesn't break stuff unless LLVM needs to be rebuilt...

[vadimcn]

Darn it! What's going on here???

[emberian]

I can't replicate the android failure locally. @alexcrichton do you know what API level the emulators are using?

[alexcrichton]

Looks like #17448, but I think that we're using api version 19 maybe?

[vadimcn]

@cmr Congrats! :-)