Pin stable, nightly versions of Rust toolchain (Azure#4486)

Resolves Azure#4258

Author: heaths

eng/cgmanifest.json

@@ -26,7 +26,7 @@
     {
       "component": {
         "type": "cargo",
-        "cargo": { "name": "cargo-audit", "version": "0.22.0" }
+        "cargo": { "name": "cargo-audit", "version": "0.22.1" }
       },
       "developmentDependency": true
     },

eng/scripts/Analyze-Code.ps1

@@ -22,6 +22,8 @@ Set-StrictMode -Version 2.0
 . ([System.IO.Path]::Combine($PSScriptRoot, '..', 'common', 'scripts', 'common.ps1'))
 . ([System.IO.Path]::Combine($PSScriptRoot, 'shared', 'Cargo.ps1'))
 
+$resolvedToolchain = [Channels]::Resolve($Toolchain)
+
 Write-Host @"
 Analyzing code with
     RUSTFLAGS: '${env:RUSTFLAGS}'
@@ -147,7 +149,7 @@ if (!$SkipPackageAnalysis) {
     Invoke-LoggedCommand "&$verifyKeywordsScript $packageManifestPath" -GroupOutput
 
     if ($Toolchain -eq 'nightly') {
-      Invoke-LoggedCommand "cargo +nightly docs-rs --manifest-path $packageManifestPath" -GroupOutput
+      Invoke-LoggedCommand "cargo +$resolvedToolchain docs-rs --manifest-path $packageManifestPath" -GroupOutput
     }
 
     if ($checkApiSupersetCrates -contains $package.Name) {

eng/scripts/Language-Settings.ps1

@@ -9,6 +9,60 @@ $SupportsTestResourcesDotenv = $true
 
 . (Join-Path $EngCommonScriptsDir "Helpers" "PSModule-Helpers.ps1")
 
+# Channel aliases used throughout scripts to pin channels.
+# Lazy-initialized static property accessors cache values on first access.
+class Channels {
+  hidden static [string] $_repoRoot = $null
+  hidden static [string] $_nightly = 'nightly-2026-04-14'
+  hidden static [string] $_stable = $null
+  hidden static [string] $_msrv = $null
+
+  static [string] Nightly() {
+    return [Channels]::_nightly
+  }
+
+  static [string] Stable() {
+    if (-not [Channels]::_stable) {
+      $path = [System.IO.Path]::Combine([Channels]::_repoRoot, 'rust-toolchain.toml')
+      [string] $content = Get-Content -Raw $path
+      [Channels]::_stable = if ($content -Match 'channel\s+=\s+"([^"]+)"') {
+        $Matches[1]
+      } else {
+        Write-Warning "Failed to get stable channel from $path"
+        'stable'
+      }
+    }
+    return [Channels]::_stable
+  }
+
+  static [string] MSRV() {
+    if (-not [Channels]::_msrv) {
+      $path = [System.IO.Path]::Combine([Channels]::_repoRoot, 'Cargo.toml')
+      [string] $content = Get-Content -Raw $path
+      [Channels]::_msrv = if ($content -Match 'rust-version\s+=\s+"([^"]+)"') {
+        $Matches[1]
+      } else {
+        Write-Warning "Failed to get MSRV from $path"
+        'stable'
+      }
+    }
+    return [Channels]::_msrv
+  }
+
+  # Resolves a toolchain alias ('stable', 'nightly', 'msrv') to its pinned version.
+  # Any other value (e.g. an explicit version) is passed through unchanged.
+  static [string] Resolve([string] $toolchain) {
+    $resolved = switch ($toolchain.ToLower()) {
+      'stable'  { [Channels]::Stable() }
+      'nightly' { [Channels]::Nightly() }
+      'msrv'    { [Channels]::MSRV() }
+      default   { $toolchain }
+    }
+    return $resolved
+  }
+}
+[Channels]::_repoRoot = $RepoRoot
+
 function SetPackageVersion ($PackageName, $Version, $ServiceDirectory, $ReleaseDate, $ReplaceLatestEntryTitle = $true) {
   if ($null -eq $ReleaseDate) {
     $ReleaseDate = Get-Date -Format "yyyy-MM-dd"

eng/scripts/Test-Packages.ps1

@@ -9,6 +9,8 @@ $ErrorActionPreference = 'Stop'
 Set-StrictMode -Version 2.0
 . "$PSScriptRoot/../common/scripts/common.ps1"
 
+$resolvedToolchain = [Channels]::Nightly()
+
 # Helper function to run cargo test with JSON output
 function Invoke-CargoTestWithJsonOutput (
   [string]$TestParams,
@@ -21,7 +23,7 @@ function Invoke-CargoTestWithJsonOutput (
   # and uploaded to DevOps for display in the Tests tab
   # (requires -Z unstable-options)
   $result = Invoke-LoggedCommand `
-    "cargo +nightly test $TestParams --manifest-path $ManifestPath --all-features --no-fail-fast -- --format json -Z unstable-options" `
+    "cargo +$resolvedToolchain test $TestParams --manifest-path $ManifestPath --all-features --no-fail-fast -- --format json -Z unstable-options" `
     -GroupOutput `
     -DoNotExitOnFailedExitCode
 

eng/scripts/Test-Semver.ps1

@@ -14,6 +14,8 @@ param(
 . ([System.IO.Path]::Combine($PSScriptRoot, '..', 'common', 'scripts', 'common.ps1'))
 . ([System.IO.Path]::Combine($PSScriptRoot, 'shared', 'Cargo.ps1'))
 
+$resolvedToolchain = [Channels]::Resolve($Toolchain)
+
 function Get-OutputPackages($workspacePackages) {
   $packages = @()
   switch ($PsCmdlet.ParameterSetName) {
@@ -64,7 +66,7 @@ $finalExitCode = 0
 foreach ($package in $outputPackages) {
   $packageName = $package.name
   $manifestPath = $package.manifest_path
-  $output = Invoke-LoggedCommand "cargo +$Toolchain semver-checks --manifest-path $manifestPath" -DoNotExitOnFailedExitCode -GroupOutput 2>&1
+  $output = Invoke-LoggedCommand "cargo +$resolvedToolchain semver-checks --manifest-path $manifestPath" -DoNotExitOnFailedExitCode -GroupOutput 2>&1
   if ($output -match 'error: no library targets found in package `(?<name>[\w_]+)`' -and $Matches['name'] -eq $packageName) {
     LogWarning "$packageName base version is a placeholder and will be ignored"
     continue

eng/scripts/Update-PackageVersion.ps1

@@ -43,6 +43,8 @@ $ErrorActionPreference = 'Stop'
 Set-StrictMode -Version 2.0
 . "$PSScriptRoot/../common/scripts/common.ps1"
 
+$resolvedToolchain = [Channels]::Nightly()
+
 Write-Host "Getting package properties for $PackageName in $ServiceDirectory."
 $pkgProperties = Get-PkgProperties -PackageName $PackageName -ServiceDirectory $ServiceDirectory
 
@@ -83,8 +85,8 @@ if ($content -ne $updated) {
   $updated | Set-Content -Path $tomlPath  -Encoding utf8 -NoNewLine
   Write-Host "Updated version in $tomlPath from $($pkgProperties.Version) to $packageSemVer."
 
-  Write-Host "Updaging dependencies in Cargo.toml files."
-  Invoke-LoggedCommand "cargo +nightly -Zscript '$RepoRoot/eng/scripts/update-pathversions.rs' update" | Out-Null
+  Write-Host "Updating dependencies in Cargo.toml files."
+  Invoke-LoggedCommand "cargo +$resolvedToolchain -Zscript '$RepoRoot/eng/scripts/update-pathversions.rs' update" | Out-Null
 
   Write-Host "Updating Cargo.lock using 'cargo update --workspace'."
   Invoke-LoggedCommand "cargo update --workspace" | Out-Null

rust-toolchain.toml

@@ -1,4 +1,5 @@
 [toolchain]
+channel = "1.95"
 components = [
   "rustc",
   "rustfmt",