Auto merge of #96737 - ChrisDenton:win-manifest, r=wesleywiser

Add Windows application manifest to rustc-main

Windows allows setting some runtime options using a manifest file. The format of the XML file is documented here: https://docs.microsoft.com/en-us/windows/win32/sbscs/application-manifests

The manifest file in this PR does three things:

* Declares which Windows versions we support. This may help avoid unnecessary compatibility shims.
* Uses the UTF-8 code page. While Rust itself uses UTF-16 APIs, other code may rely on the code page.
* Makes the application long path aware (if also enabled by the user). This allows for the current directory to be longer than `PATH_MAX`.

These changes only affect the `rustc` process and not any other DLLs or compiled programs.

2 files changed, 52 insertions, 0 deletions

diff --git a/compiler/rustc/Windows Manifest.xml b/compiler/rustc/Windows Manifest.xml
new file mode 100644
index 00000000000..b37a2fd4c76
--- /dev/null
+++ b/compiler/rustc/Windows Manifest.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<!--
+This is a Windows application manifest file.
+See: https://docs.microsoft.com/en-us/windows/win32/sbscs/application-manifests
+-->
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
+    <!-- Versions rustc supports as compiler hosts -->
+    <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1"> 
+        <application> 
+            <!-- Windows 7 --><supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/>
+            <!-- Windows 8 --><supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}"/>
+            <!-- Windows 8.1 --><supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}"/>
+            <!-- Windows 10 and 11 --><supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}"/>
+        </application> 
+    </compatibility>
+    <!-- Use UTF-8 code page -->
+    <asmv3:application>
+        <asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">
+            <activeCodePage>UTF-8</activeCodePage>
+        </asmv3:windowsSettings>
+    </asmv3:application>
+    <!-- Remove (most) legacy path limits -->
+    <asmv3:application>
+        <asmv3:windowsSettings xmlns:ws2="http://schemas.microsoft.com/SMI/2016/WindowsSettings">
+            <ws2:longPathAware>true</ws2:longPathAware>
+        </asmv3:windowsSettings>
+    </asmv3:application>
+</assembly>
diff --git a/compiler/rustc/build.rs b/compiler/rustc/build.rs
new file mode 100644
index 00000000000..24c06c0ddbf
--- /dev/null
+++ b/compiler/rustc/build.rs
@@ -0,0 +1,24 @@
+use std::env;
+
+fn main() {
+    let target_os = env::var("CARGO_CFG_TARGET_OS");
+    let target_env = env::var("CARGO_CFG_TARGET_ENV");
+    if Ok("windows") == target_os.as_deref() && Ok("msvc") == target_env.as_deref() {
+        set_windows_exe_options();
+    }
+}
+
+// Add a manifest file to rustc.exe.
+fn set_windows_exe_options() {
+    static WINDOWS_MANIFEST_FILE: &str = "Windows Manifest.xml";
+
+    let mut manifest = env::current_dir().unwrap();
+    manifest.push(WINDOWS_MANIFEST_FILE);
+
+    println!("cargo:rerun-if-changed={}", WINDOWS_MANIFEST_FILE);
+    // Embed the Windows application manifest file.
+    println!("cargo:rustc-link-arg-bin=rustc-main=/MANIFEST:EMBED");
+    println!("cargo:rustc-link-arg-bin=rustc-main=/MANIFESTINPUT:{}", manifest.to_str().unwrap());
+    // Turn linker warnings into errors.
+    println!("cargo:rustc-link-arg-bin=rustc-main=/WX");
+}