Rollup merge of #105354 - BlackHoleFox:apple-deployment-printer, r=oli-obk

Add deployment-target --print flag for Apple targets

This is very useful for crates that need to know what the Apple OS deployment target is for their build scripts or inside of a build environment. Right now, the defaults just get copy/pasted around the ecosystem since they've been stable for so long. But with #104385 in progress, that won't be true anymore and everything will need to move. Ideally whenever it happens again, this could be less painful as everything can ask the compiler what its default is instead.

To show examples of the copy/paste proliferation, here's some crates and/or apps that do:
- [cc](https://github.com/rust-lang/cc-rs/pull/708/files), Soon
-  [mac-notification-sys](https://github.com/h4llow3En/mac-notification-sys/pull/46/files#diff-d0d98998092552a1d3259338c2c71e118a5b8343dd4703c0c7f552ada7f9cb42R10-R12)
- [PyO3](https://github.com/PyO3/maturin/blob/ccb02d1aa1cc41e82a3572a3c8b35cace15f3e78/src/target.rs#L755-L758)
- [Anki](https://github.com/ankitects/anki/blob/613b5c1034cc9943f3f68d818ae22b2e0acec877/build/runner/src/bundle/artifacts.rs#L49-L54)
- [jsc-rs](https://github.com/Brooooooklyn/jsc-rs/blob/37767267568fb2de62fc441473e7d158dd980520/xtask/src/build.rs#L402-L405)
... and probably more that a simple GitHub codesearch didn't see

2 files changed, 7 insertions, 1 deletions

diff --git a/src/doc/rustc/src/command-line-arguments.md b/src/doc/rustc/src/command-line-arguments.md
index d4d26654ed1..3be4382b0a3 100644
--- a/src/doc/rustc/src/command-line-arguments.md
+++ b/src/doc/rustc/src/command-line-arguments.md
@@ -248,8 +248,14 @@ The valid types of print values are:
   exact format of this debugging output is not a stable guarantee, other than
   that it will include the linker executable and the text of each command-line
   argument passed to the linker.
+- `deployment-target` - The currently selected [deployment target] (or minimum OS version)
+  for the selected Apple platform target. This value can be used or passed along to other
+  components alongside a Rust build that need this information, such as C compilers.
+  This returns rustc's minimum supported deployment target if no `*_DEPLOYMENT_TARGET` variable
+  is present in the environment, or otherwise returns the variable's parsed value.
 
 [conditional compilation]: ../reference/conditional-compilation.html
+[deployment target]: https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/cross_development/Configuring/configuring.html
 
 <a id="option-g-debug"></a>
 ## `-g`: include debug information
diff --git a/src/tools/tidy/src/ui_tests.rs b/src/tools/tidy/src/ui_tests.rs
index a2f7b8ba7be..e4f328ec0dd 100644
--- a/src/tools/tidy/src/ui_tests.rs
+++ b/src/tools/tidy/src/ui_tests.rs
@@ -10,7 +10,7 @@ use std::path::{Path, PathBuf};
 const ENTRY_LIMIT: usize = 900;
 // FIXME: The following limits should be reduced eventually.
 const ISSUES_ENTRY_LIMIT: usize = 1953;
-const ROOT_ENTRY_LIMIT: usize = 894;
+const ROOT_ENTRY_LIMIT: usize = 895;
 
 fn check_entries(tests_path: &Path, bad: &mut bool) {
     let mut directories: HashMap<PathBuf, usize> = HashMap::new();