Rollup merge of #139451 - madsmtm:apple-target-env-abi, r=wesleywiser

Add `target_env = "macabi"` and `target_env = "sim"`

[RFC 2992](https://github.com/rust-lang/rfcs/pull/2992) ([tracking issue](https://github.com/rust-lang/rust/issues/80970)) introduced `cfg(target_abi = ...)` with the original motivation being Mac Catalyst and Apple Simulator targets. These do not actually have a changed calling convention in the same sense that e.g. `cfg(target_abi = "eabihf")` or pointer authentication (`arm64e`) does, see https://github.com/rust-lang/rust/issues/133331.

Specifically, for Apple Simulator targets, the binary runs under the following conditions:
- Runs with the host macOS kernel (but in a mode configured for iOS/tvOS/...).
- Uses frameworks for the specific simulator version being targetted.
- System file accesses need to be made relative to the `IPHONE_SIMULATOR_ROOT` environment variable.
- Uses host GPUs directly.

And for Mac Catalyst:
- Runs with the host macOS kernel (but in a mode configured for iOS).
- Uses mostly host macOS frameworks (though with a few things changed, e.g. the [`NSImageResizingModeStretch`](https://developer.apple.com/documentation/appkit/nsimage/resizingmode-swift.enum/stretch?language=objc) enum has a different value).
- Uses host GPUs, camera and other peripherals directly.

As can be seen, these seem better suited as `target_env`s, since it really is the environment that the binary is running under that's changed (regardless of the Mac Catalyst "macabi" having "abi" in the name). So this PR adds `target_env = "sim"` and `target_env = "macabi"`, with the idea of possibly deprecating `target_abi = "sim"` and `target_abi = "macabi"` in the far future.

This affects iOS Tier 2 targets (`aarch64-apple-ios-sim`, `x86_64-apple-ios`, `aarch64-apple-ios-macabi` and `x86_64-apple-ios-macabi`), and probably needs a compiler FCP.

Fixes https://github.com/rust-lang/rust/issues/133331.
Reference PR: https://github.com/rust-lang/reference/pull/1781.
Cargo doc PR: https://github.com/rust-lang/cargo/pull/15404.

r? compiler
CC `@workingjubilee`
CC target maintainers `@deg4uss3r` `@thomcc` `@badboy` `@BlackHoleFox` `@madsmtm` `@agg23`

2 files changed, 6 insertions, 6 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/apple.rs b/compiler/rustc_codegen_ssa/src/back/apple.rs
index d242efaf4fd..2f68bad1695 100644
--- a/compiler/rustc_codegen_ssa/src/back/apple.rs
+++ b/compiler/rustc_codegen_ssa/src/back/apple.rs
@@ -17,7 +17,7 @@ mod tests;
 
 /// The canonical name of the desired SDK for a given target.
 pub(super) fn sdk_name(target: &Target) -> &'static str {
-    match (&*target.os, &*target.abi) {
+    match (&*target.os, &*target.env) {
         ("macos", "") => "MacOSX",
         ("ios", "") => "iPhoneOS",
         ("ios", "sim") => "iPhoneSimulator",
@@ -34,7 +34,7 @@ pub(super) fn sdk_name(target: &Target) -> &'static str {
 }
 
 pub(super) fn macho_platform(target: &Target) -> u32 {
-    match (&*target.os, &*target.abi) {
+    match (&*target.os, &*target.env) {
         ("macos", _) => object::macho::PLATFORM_MACOS,
         ("ios", "macabi") => object::macho::PLATFORM_MACCATALYST,
         ("ios", "sim") => object::macho::PLATFORM_IOSSIMULATOR,
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index b69fbf61185..6e21f54587f 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -3026,7 +3026,7 @@ pub(crate) fn are_upstream_rust_objects_already_included(sess: &Session) -> bool
 /// We need to communicate five things to the linker on Apple/Darwin targets:
 /// - The architecture.
 /// - The operating system (and that it's an Apple platform).
-/// - The environment / ABI.
+/// - The environment.
 /// - The deployment target.
 /// - The SDK version.
 fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
@@ -3040,7 +3040,7 @@ fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavo
     // `sess.target.arch` (`target_arch`) is not detailed enough.
     let llvm_arch = sess.target.llvm_target.split_once('-').expect("LLVM target must have arch").0;
     let target_os = &*sess.target.os;
-    let target_abi = &*sess.target.abi;
+    let target_env = &*sess.target.env;
 
     // The architecture name to forward to the linker.
     //
@@ -3091,14 +3091,14 @@ fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavo
         // > - visionos-simulator
         // > - xros-simulator
         // > - driverkit
-        let platform_name = match (target_os, target_abi) {
+        let platform_name = match (target_os, target_env) {
             (os, "") => os,
             ("ios", "macabi") => "mac-catalyst",
             ("ios", "sim") => "ios-simulator",
             ("tvos", "sim") => "tvos-simulator",
             ("watchos", "sim") => "watchos-simulator",
             ("visionos", "sim") => "visionos-simulator",
-            _ => bug!("invalid OS/ABI combination for Apple target: {target_os}, {target_abi}"),
+            _ => bug!("invalid OS/env combination for Apple target: {target_os}, {target_env}"),
         };
 
         let min_version = sess.apple_deployment_target().fmt_full().to_string();