Stop clearing LastExitCode

The clearing of $LastExitCode in our Exec function is masking failures
of windows commands.  Cannot understand why this is the case but easy to
demonstrate in practice.

build/scripts/build-utils.ps1

@@ -11,29 +11,35 @@ $ErrorActionPreference="Stop"
 # fails.  
 # 
 # Original sample came from: http://jameskovacs.com/2010/02/25/the-exec-problem/
-function Exec([scriptblock]$cmd, [string]$errorMessage = "Error executing command: " + $cmd) { 
-    # Clear LastExitCode before invoking the script so a windows command failure
-    # before doesn't carry over.  Can happen if the expression is pure powershell
-    # and not wrapping a windows command.
-    $lastexitcode = 0
-
-    $output = & $cmd 
+function Exec([scriptblock]$cmd, [switch]$echo = $false) {
+    if ($echo) {
+        & $cmd
+    }
+    else {
+        $output = & $cmd 
+    }
 
     # Need to check both of these cases for errors as they represent different items
     # - $?: did the powershell script block throw an error
     # - $lastexitcode: did a windows command executed by the script block end in error
     if ((-not $?) -or ($lastexitcode -ne 0)) {
-        Write-Host $output
-        throw $errorMessage 
+        if (-not $echo) { 
+            Write-Host $output
+        }
+        throw "Command failed to execute: $cmd"
     } 
 }
 
+function Exec-Echo([scriptblock]$cmd) {
+    Exec $cmd -echo:$true
+}
+
 # Handy function for executing Invoke-Expression and reliably throwing an 
 # error if the expression, or the command it invoked, fails
 # 
 # Original sample came from: http://jameskovacs.com/2010/02/25/the-exec-problem/
 function Exec-Expression([string]$expr) {
-    Exec { Invoke-Expression $expr }
+    Exec { Invoke-Expression $expr } -echo:$true
 }
 
 # Ensure that NuGet is installed and return the path to the 

build/scripts/cibuild.ps1

@@ -87,7 +87,7 @@ try {
     Redirect-Temp
 
     if ($testBuildCorrectness) {
-        Exec { & ".\build\scripts\test-build-correctness.ps1" $repoDir $configDir }
+        Exec-Echo { & ".\build\scripts\test-build-correctness.ps1" -config $buildConfiguration }
         exit 0
     }
 

build/scripts/test-build-correctness.ps1

@@ -11,51 +11,47 @@
 
 [CmdletBinding(PositionalBinding=$false)]
 param(
-    [string]$sourcePath = $null,
-    [string]$binariesPath = $null
+    [string]$config = "",
+    [string]$msbuild = ""
 )
 
 Set-StrictMode -version 2.0
 $ErrorActionPreference="Stop"
 
-function Get-PackagesPath {
-    $packagesPath = $env:NUGET_PACKAGES
-    if ($packagesPath -eq $null) {
-        $packagesPath = Join-Path $env:UserProfile ".nuget\packages\"
-    }
-
-    return $packagesPath
-}
-
-Push-Location $sourcePath
 try {
+    . (Join-Path $PSScriptRoot "build-utils.ps1")
+    Push-Location $repoDir
 
     # Need to parse out the current NuGet package version of Structured Logger
-    [xml]$deps = Get-Content (Join-Path $sourcePath "build\Targets\Dependencies.props")
+    [xml]$deps = Get-Content (Join-Path $repoDir "build\Targets\Dependencies.props")
     $structuredLoggerVersion = $deps.Project.PropertyGroup.MicrosoftBuildLoggingStructuredLoggerVersion
-    $packagesPath = Get-PackagesPath
-    $structuredLoggerPath = Join-Path $packagesPath "Microsoft.Build.Logging.StructuredLogger\$structuredLoggerVersion\lib\net46\StructuredLogger.dll"
-    $logPath = Join-Path $binariesPath "build.xml"
+    $structuredLoggerPath = Join-Path (Get-PackagesDir) "Microsoft.Build.Logging.StructuredLogger\$structuredLoggerVersion\lib\net46\StructuredLogger.dll"
+    $configDir = Join-Path $binariesDir $config
+    $logPath = Join-Path $configDir "build.xml"
+
+    if ($msbuild -eq "") {
+        $msbuild = Ensure-MSBuild
+    }
 
     Write-Host "Building Roslyn.sln with logging support"
-    Exec { & msbuild /v:m /m /logger:StructuredLogger`,$structuredLoggerPath`;$logPath /nodeReuse:false /p:DeployExtension=false Roslyn.sln }
+    Exec-Echo { & $msbuild /v:m /m /logger:StructuredLogger`,$structuredLoggerPath`;$logPath /nodeReuse:false /p:DeployExtension=false Roslyn.sln }
     Write-Host ""
 
     # Verify the state of our various build artifacts
     Write-Host "Running BuildBoss"
-    $buildBossPath = Join-Path $binariesPath "Exes\BuildBoss\BuildBoss.exe"
-    Exec { & $buildBossPath Roslyn.sln Compilers.sln src\Samples\Samples.sln CrossPlatform.sln "build\Targets" $logPath }
+    $buildBossPath = Join-Path $configDir "Exes\BuildBoss\BuildBoss.exe"
+    Exec-Echo { & $buildBossPath Roslyn.sln Compilers.sln src\Samples\Samples.sln CrossPlatform.sln "build\Targets" $logPath }
     Write-Host ""
 
     # Verify the state of our project.jsons
     Write-Host "Running RepoUtil"
-    $repoUtilPath = Join-Path $binariesPath "Exes\RepoUtil\RepoUtil.exe"
-    Exec { & $repoUtilPath verify }
+    $repoUtilPath = Join-Path $configDir "Exes\RepoUtil\RepoUtil.exe"
+    Exec-Echo { & $repoUtilPath verify }
     Write-Host ""
 
     # Verify the state of our generated syntax files
     Write-Host "Checking generated compiler files"
-    Exec { & (Join-Path $PSScriptRoot "generate-compiler-code.ps1") -test }
+    Exec-Echo { & (Join-Path $PSScriptRoot "generate-compiler-code.ps1") -test }
 
     exit 0
 }