Fan out rust-ci-full nextest by platform

.github/actions/setup-msvc-env/action.yml

@@ -0,0 +1,17 @@
+name: setup-msvc-env
+description: Expose an MSVC developer environment for the requested Windows target.
+inputs:
+  target:
+    description: Rust target triple that will be built on this Windows runner.
+    required: true
+  host-arch:
+    description: Optional Visual Studio host architecture override.
+    required: false
+    default: ""
+
+runs:
+  using: composite
+  steps:
+    - name: Expose MSVC SDK environment
+      shell: pwsh
+      run: '& "$env:GITHUB_ACTION_PATH/setup-msvc-env.ps1" -Target "${{ inputs.target }}" -HostArch "${{ inputs.host-arch }}"'

.github/actions/setup-msvc-env/setup-msvc-env.ps1

@@ -0,0 +1,257 @@
+param(
+    [Parameter(Mandatory = $true)]
+    [string]$Target,
+
+    [string]$HostArch = ""
+)
+
+# Cargo can cross-compile the Rust code for Windows ARM64 on a Windows x64
+# runner, but rustup alone does not expose the matching MSVC/UCRT include and
+# library paths. Ask Visual Studio for the target-specific developer
+# environment, then persist the relevant variables through GITHUB_ENV so the
+# later Cargo step sees the same environment as a normal VsDevCmd shell.
+switch ($Target) {
+    "x86_64-pc-windows-msvc" {
+        $TargetArch = "x64"
+        $RequiredComponent = "Microsoft.VisualStudio.Component.VC.Tools.x86.x64"
+    }
+    "aarch64-pc-windows-msvc" {
+        $TargetArch = "arm64"
+        $RequiredComponent = "Microsoft.VisualStudio.Component.VC.Tools.ARM64"
+    }
+    default {
+        throw "Unsupported Windows MSVC target: $Target"
+    }
+}
+
+# VsDevCmd needs both sides of the cross compile: the architecture of the
+# machine running the tools and the architecture of the binaries being linked.
+# Infer the host from the runner unless a caller needs to override it.
+if (-not $HostArch) {
+    $HostArch = if ($env:PROCESSOR_ARCHITEW6432 -eq "ARM64" -or $env:PROCESSOR_ARCHITECTURE -eq "ARM64") {
+        "arm64"
+    } else {
+        "x64"
+    }
+}
+
+$VsWhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+if (-not (Test-Path $VsWhere)) {
+    throw "vswhere.exe not found"
+}
+
+# Require the target VC tools component, not merely any Visual Studio install,
+# so an x64 archive producer cannot silently link ARM64 tests with the wrong
+# SDK/toolchain layout.
+$InstallPath = & $VsWhere -latest -products * -requires $RequiredComponent -property installationPath 2>$null
+if (-not $InstallPath) {
+    throw "Could not locate a Visual Studio installation with component $RequiredComponent"
+}
+
+$VsDevCmd = Join-Path $InstallPath "Common7\Tools\VsDevCmd.bat"
+if (-not (Test-Path $VsDevCmd)) {
+    throw "VsDevCmd.bat not found at $VsDevCmd"
+}
+
+$VarsToExport = @(
+    "INCLUDE",
+    "LIB",
+    "LIBPATH",
+    "PATH",
+    "UCRTVersion",
+    "UniversalCRTSdkDir",
+    "VCINSTALLDIR",
+    "VCToolsInstallDir",
+    "WindowsLibPath",
+    "WindowsSdkBinPath",
+    "WindowsSdkDir",
+    "WindowsSDKLibVersion",
+    "WindowsSDKVersion"
+)
+
+# Run VsDevCmd inside cmd.exe because it is a batch file, then copy just the
+# variables Cargo/rustc need into the GitHub Actions environment file. PowerShell
+# cannot mutate the parent composite-action environment directly.
+$EnvLines = & cmd.exe /c ('"{0}" -no_logo -arch={1} -host_arch={2} >nul && set' -f $VsDevCmd, $TargetArch, $HostArch)
+$VcToolsInstallDir = $null
+foreach ($Line in $EnvLines) {
+    if ($Line -notmatch "^(.*?)=(.*)$") {
+        continue
+    }
+
+    $Name = $Matches[1]
+    $Value = $Matches[2]
+    if ($VarsToExport -contains $Name) {
+        if ($Name -ieq "Path") {
+            $Name = "PATH"
+        }
+        if ($Name -eq "VCToolsInstallDir") {
+            $VcToolsInstallDir = $Value
+        }
+        "$Name=$Value" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+    }
+}
+
+if (-not $VcToolsInstallDir) {
+    throw "VCToolsInstallDir was not exported by VsDevCmd.bat"
+}
+
+# Prefer Rust's bundled linker when rustup provides one, then Visual Studio's
+# LLVM linker, and finally MSVC link.exe. This keeps the cross-compile path close
+# to Rust's normal Windows MSVC behavior while still working on runner images
+# where one of those linkers is absent.
+$Linker = $null
+$Rustc = Get-Command rustc -ErrorAction SilentlyContinue
+if ($Rustc) {
+    $Sysroot = (& rustc --print sysroot 2>$null).Trim()
+    $RustHost = & rustc -vV 2>$null | Select-String "^host: " | ForEach-Object { $_.Line.Substring(6) }
+    if ($RustHost) {
+        $RustHost = $RustHost.Trim()
+    }
+    if ($Sysroot -and $RustHost) {
+        $RustLld = Join-Path $Sysroot "lib\rustlib\$RustHost\bin\rust-lld.exe"
+        if (Test-Path $RustLld) {
+            $Linker = $RustLld
+        }
+    }
+}
+if (-not $Linker) {
+    $Linker = Join-Path $InstallPath "VC\Tools\Llvm\x64\bin\lld-link.exe"
+}
+if (-not (Test-Path $Linker)) {
+    $Linker = Join-Path $VcToolsInstallDir "bin\Host${HostArch}\${TargetArch}\link.exe"
+}
+if (-not (Test-Path $Linker)) {
+    throw "Windows linker not found at $Linker"
+}
+
+# rustc passes `/arm64hazardfree` for ARM64 MSVC links. The lld variants on our
+# Windows x64 archive producers reject that flag, including when rustc places it
+# inside a response file. Compile a tiny forwarding wrapper that strips only
+# that unsupported flag, then delegate every other argument to the real linker.
+if ($TargetArch -eq "arm64" -and (Split-Path -Leaf $Linker) -match "lld") {
+    $WrapperDir = Join-Path $env:RUNNER_TEMP "msvc-lld-wrapper"
+    New-Item -Path $WrapperDir -ItemType Directory -Force | Out-Null
+    $WrapperPath = Join-Path $WrapperDir "lld-link-wrapper.exe"
+    $WrapperSource = @'
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Text;
+using System.Text.RegularExpressions;
+
+internal static class Program
+{
+    private static int Main(string[] args)
+    {
+        var linker = Environment.GetEnvironmentVariable("MSVC_REAL_LINKER");
+        if (string.IsNullOrEmpty(linker))
+        {
+            Console.Error.WriteLine("MSVC_REAL_LINKER is not set");
+            return 1;
+        }
+
+        var startInfo = new ProcessStartInfo(linker)
+        {
+            UseShellExecute = false,
+        };
+        var filteredArgs = new List<string> { "-flavor", "link", "/defaultlib:ucrt", "/nodefaultlib:libucrt" };
+        foreach (var arg in args)
+        {
+            if (!string.Equals(arg, "/arm64hazardfree", StringComparison.OrdinalIgnoreCase))
+            {
+                filteredArgs.Add(QuoteArgument(FilterResponseFile(arg)));
+            }
+        }
+        startInfo.Arguments = string.Join(" ", filteredArgs);
+
+        using var process = Process.Start(startInfo);
+        if (process is null)
+        {
+            Console.Error.WriteLine($"Failed to start linker: {linker}");
+            return 1;
+        }
+
+        process.WaitForExit();
+        return process.ExitCode;
+    }
+
+    private static string FilterResponseFile(string argument)
+    {
+        if (argument.Length < 2 || argument[0] != '@')
+        {
+            return argument;
+        }
+
+        var responsePath = argument.Substring(1);
+        if (!File.Exists(responsePath))
+        {
+            return argument;
+        }
+
+        var filteredResponsePath = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName() + ".rsp");
+        var responseContents = Regex.Replace(
+            File.ReadAllText(responsePath),
+            "/arm64hazardfree",
+            string.Empty,
+            RegexOptions.IgnoreCase);
+        File.WriteAllText(filteredResponsePath, responseContents);
+        return "@" + filteredResponsePath;
+    }
+
+    private static string QuoteArgument(string argument)
+    {
+        if (argument.Length == 0)
+        {
+            return "\"\"";
+        }
+        if (argument.IndexOfAny(new[] { ' ', '\t', '"' }) < 0)
+        {
+            return argument;
+        }
+
+        var quoted = new StringBuilder("\"");
+        var backslashes = 0;
+        foreach (var character in argument)
+        {
+            if (character == '\\')
+            {
+                backslashes++;
+                continue;
+            }
+            if (character == '"')
+            {
+                quoted.Append('\\', (backslashes * 2) + 1);
+                quoted.Append(character);
+                backslashes = 0;
+                continue;
+            }
+
+            quoted.Append('\\', backslashes);
+            backslashes = 0;
+            quoted.Append(character);
+        }
+        quoted.Append('\\', backslashes * 2);
+        quoted.Append('"');
+        return quoted.ToString();
+    }
+}
+'@
+    $WrapperSourcePath = Join-Path $WrapperDir "lld-link-wrapper.cs"
+    $WrapperSource | Out-File -FilePath $WrapperSourcePath -Encoding utf8
+    $Csc = Join-Path $InstallPath "MSBuild\Current\Bin\Roslyn\csc.exe"
+    if (-not (Test-Path $Csc)) {
+        throw "csc.exe not found at $Csc"
+    }
+    & $Csc /nologo /target:exe /out:$WrapperPath $WrapperSourcePath
+    if ($LASTEXITCODE -ne 0) {
+        throw "Failed to compile lld-link wrapper"
+    }
+    "MSVC_REAL_LINKER=$Linker" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+    $Linker = $WrapperPath
+}
+
+Write-Output "Using Windows linker: $Linker"
+$CargoTarget = $Target.ToUpperInvariant().Replace("-", "_")
+"CARGO_TARGET_${CargoTarget}_LINKER=$Linker" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append

.github/scripts/setup-dev-drive.ps1

@@ -0,0 +1,62 @@
+# Configure a fast drive for Windows CI jobs.
+#
+# GitHub-hosted Windows runners do not always expose a secondary D: volume. When
+# they do not, try to create a Dev Drive VHD and fall back to C: if the runner
+# image does not allow that provisioning path.
+
+function Use-FallbackDrive {
+    param([string]$Reason)
+
+    Write-Warning "$Reason Falling back to C:"
+    return "C:"
+}
+
+function Invoke-BestEffort {
+    param([scriptblock]$Script, [string]$Description)
+
+    try {
+        & $Script
+    } catch {
+        Write-Warning "$Description failed: $($_.Exception.Message)"
+    }
+}
+
+if (Test-Path "D:\") {
+    Write-Output "Using existing drive at D:"
+    $Drive = "D:"
+} else {
+    try {
+        $VhdPath = Join-Path $env:RUNNER_TEMP "codex-dev-drive.vhdx"
+        $SizeBytes = 64GB
+
+        if (Test-Path $VhdPath) {
+            Remove-Item -Path $VhdPath -Force
+        }
+
+        New-VHD -Path $VhdPath -SizeBytes $SizeBytes -Dynamic -ErrorAction Stop | Out-Null
+        $Mounted = Mount-VHD -Path $VhdPath -Passthru -ErrorAction Stop
+        $Disk = $Mounted | Get-Disk -ErrorAction Stop
+        $Disk | Initialize-Disk -PartitionStyle GPT -ErrorAction Stop
+        $Partition = $Disk | New-Partition -AssignDriveLetter -UseMaximumSize -ErrorAction Stop
+        $Volume = $Partition | Format-Volume -FileSystem ReFS -NewFileSystemLabel "CodexDevDrive" -DevDrive -Confirm:$false -Force -ErrorAction Stop
+
+        $Drive = "$($Volume.DriveLetter):"
+
+        Invoke-BestEffort { fsutil devdrv trust $Drive } "Trusting Dev Drive $Drive"
+        Invoke-BestEffort { fsutil devdrv enable /disallowAv } "Disabling AV filter attachment for Dev Drives"
+        Invoke-BestEffort { fsutil devdrv query $Drive } "Querying Dev Drive $Drive"
+
+        Write-Output "Using Dev Drive at $Drive"
+    } catch {
+        $Drive = Use-FallbackDrive "Failed to create Dev Drive: $($_.Exception.Message)"
+    }
+}
+
+$Tmp = "$Drive\codex-tmp"
+New-Item -Path $Tmp -ItemType Directory -Force | Out-Null
+
+@(
+    "DEV_DRIVE=$Drive"
+    "TMP=$Tmp"
+    "TEMP=$Tmp"
+) | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append

.github/workflows/README.md

@@ -21,7 +21,8 @@ The workflows in this directory are split so that pull requests get fast, review
 - `rust-ci-full.yml` is the full Cargo-native verification workflow.
   It keeps the heavier checks off the PR path while still validating them after merge:
   - the full Cargo `clippy` matrix
-  - the full Cargo `nextest` matrix
+  - the full Cargo `nextest` matrix via per-platform archive-backed shards
+  - Windows ARM64 nextest archives cross-compiled on Windows x64, then replayed on native Windows ARM64 shards
   - release-profile Cargo builds
   - cross-platform `argument-comment-lint`
   - Linux remote-env tests