Rollup merge of rust-lang#128873 - ChrisDenton:windows-targets, r=Mark-Simulacrum

Add windows-targets crate to std's sysroot

With this PR, when backtrace is used as a crate from crates.io it will (once updated) use the real [windows-targets](https://crates.io/crates/windows-targets) crate. But when used from std it'll use std's replacement version.

This allows sharing our customized `windows_tagets::link!` macro between std proper and the backtrace crate when used as part of std, ensuring a consistent linking story. This will be especially important once we move to using [`raw-dylib`](https://doc.rust-lang.org/reference/items/external-blocks.html#dylib-versus-raw-dylib) by default.

Author: matthiaskrgr

Cargo.lock

@@ -8,6 +8,7 @@ members = [
 exclude = [
   # stdarch has its own Cargo workspace
   "stdarch",
+  "windows_targets"
 ]
 
 [profile.release.package.compiler_builtins]

Cargo.toml

@@ -57,6 +57,9 @@ object = { version = "0.36.0", default-features = false, optional = true, featur
     'archive',
 ] }
 
+[target.'cfg(windows)'.dependencies.windows-targets]
+path = "../windows_targets"
+
 [dev-dependencies]
 rand = { version = "0.8.5", default-features = false, features = ["alloc"] }
 rand_xorshift = "0.3.0"
@@ -116,7 +119,7 @@ std_detect_env_override = ["std_detect/std_detect_env_override"]
 
 # Enable using raw-dylib for Windows imports.
 # This will eventually be the default.
-windows_raw_dylib = []
+windows_raw_dylib = ["windows-targets/windows_raw_dylib"]
 
 [package.metadata.fortanix-sgx]
 # Maximum possible number of threads when testing

std/Cargo.toml

@@ -4,7 +4,7 @@ use crate::alloc::{GlobalAlloc, Layout, System};
 use crate::ffi::c_void;
 use crate::ptr;
 use crate::sync::atomic::{AtomicPtr, Ordering};
-use crate::sys::c::{self, windows_targets};
+use crate::sys::c;
 use crate::sys::common::alloc::{realloc_fallback, MIN_ALIGN};
 
 #[cfg(test)]

std/src/sys/pal/windows/alloc.rs

@@ -8,8 +8,6 @@
 use core::ffi::{c_uint, c_ulong, c_ushort, c_void, CStr};
 use core::{mem, ptr};
 
-pub(super) mod windows_targets;
-
 mod windows_sys;
 pub use windows_sys::*;
 

std/src/sys/pal/windows/c.rs

@@ -3317,4 +3317,3 @@ pub struct WSADATA {
 #[cfg(target_arch = "arm")]
 pub enum CONTEXT {}
 // ignore-tidy-filelength
-use super::windows_targets;

std/src/sys/pal/windows/c/windows_sys.rs

@@ -0,0 +1,10 @@
+[package]
+name = "windows-targets"
+description = "A drop-in replacement for the real windows-targets crate for use in std only."
+version = "0.0.0"
+edition = "2021"
+
+[features]
+# Enable using raw-dylib for Windows imports.
+# This will eventually be the default.
+windows_raw_dylib = []

windows_targets/Cargo.toml

@@ -2,6 +2,10 @@
 //!
 //! This is a simple wrapper around an `extern` block with a `#[link]` attribute.
 //! It's very roughly equivalent to the windows-targets crate.
+#![no_std]
+#![no_core]
+#![feature(decl_macro)]
+#![feature(no_core)]
 
 #[cfg(feature = "windows_raw_dylib")]
 pub macro link {