Rollup merge of #117702 - davidtwco:target-tier-refactors, r=petrochenkov

target: move base and target specifications

Follow-up to #116004.

In anticipation of later PRs where we'll want to add tidy checks to ensure that, for each target, we have a test or a platform support document or something like that, this PR moves target specifications into a directory on their own so that we can just list the files in this directory to get a list of all targets.

- Base specifications are moved to `rustc_target::spec::base`.
- Target specifications are moved to `rustc_target::spec::targets`.
- All the other source files containing types used in the target specs remain in `rustc_target::spec`.
  - `rustc_target/src/spec/abi.rs` is moved to `rustc_target/src/spec/abi/mod.rs` (where there was already a `tests.rs`) for uniformity.

r? ``@petrochenkov``

Author: GuillaumeGomez

compiler/rustc_target/src/spec/aarch64_fuchsia.rs

@@ -1,7 +1,7 @@
-use crate::spec::{SanitizerSet, TargetOptions};
+use crate::spec::{base, SanitizerSet, TargetOptions};
 
 pub fn opts() -> TargetOptions {
-    let mut base = super::linux_base::opts();
+    let mut base = base::linux::opts();
     base.os = "android".into();
     base.is_like_android = true;
     base.default_dwarf_version = 2;

compiler/rustc_target/src/spec/abi.rs renamed to compiler/rustc_target/src/spec/abi/mod.rs

@@ -1,10 +1,10 @@
 use std::{borrow::Cow, env};
 
+use crate::spec::{add_link_args, add_link_args_iter};
 use crate::spec::{cvs, Cc, DebuginfoKind, FramePointer, LinkArgs};
 use crate::spec::{LinkerFlavor, Lld, SplitDebuginfo, StaticCow, Target, TargetOptions};
 
 #[cfg(test)]
-#[path = "apple/tests.rs"]
 mod tests;
 
 use Arch::*;
@@ -102,13 +102,13 @@ fn pre_link_args(os: &'static str, arch: Arch, abi: &'static str) -> LinkArgs {
         LinkerFlavor::Darwin(Cc::No, Lld::No),
         &["-arch", arch, "-platform_version"],
     );
-    super::add_link_args_iter(
+    add_link_args_iter(
         &mut args,
         LinkerFlavor::Darwin(Cc::No, Lld::No),
         [platform_name, platform_version.clone(), platform_version].into_iter(),
     );
     if abi != "macabi" {
-        super::add_link_args(&mut args, LinkerFlavor::Darwin(Cc::Yes, Lld::No), &["-arch", arch]);
+        add_link_args(&mut args, LinkerFlavor::Darwin(Cc::Yes, Lld::No), &["-arch", arch]);
     }
 
     args

compiler/rustc_target/src/spec/avr_unknown_gnu_atmega328.rs

@@ -1,4 +1,4 @@
-use crate::spec::{
+use crate::spec::targets::{
     aarch64_apple_darwin, aarch64_apple_ios_sim, aarch64_apple_watchos_sim, i686_apple_darwin,
     x86_64_apple_darwin, x86_64_apple_ios, x86_64_apple_tvos, x86_64_apple_watchos_sim,
 };