Make build.FullCLR.ps1 script more user friendly:

error messages + -G parameter support for cmake

build.FullCLR.ps1

@@ -1,6 +1,42 @@
+param(
+    [ValidateSet(
+        "",
+        "Visual Studio 12 2013", 
+        "Visual Studio 12 2013 Win64",
+        "Visual Studio 14 2015", 
+        "Visual Studio 14 2015 Win64")]
+    [string]$cmakeGenerator = ""
+)
+
 $origPWD = $pwd
 try
 {
+    $prechecks = $true    
+    # check per-requests
+    if (-not (get-command cmake -ErrorAction SilentlyContinue))
+    {
+        Write-Warning 'cmake not found. You can install it from https://chocolatey.org/packages/cmake.portable'
+        $prechecks = $false
+    }
+
+    if (-not (get-command msbuild -ErrorAction SilentlyContinue))
+    {
+        Write-Warning 'msbuild not found. Install Visual Studio and add msbuild to $env:PATH'
+        $prechecks = $false
+    }
+
+    if (-not (get-command dotnet -ErrorAction SilentlyContinue))
+    {
+        Write-Warning 'dotnet not found. Install it from http://dotnet.github.io/getting-started/'
+        $prechecks = $false
+    }
+
+    if (-not $prechecks)
+    {
+        return
+    }
+    # end per-requests
+
     $BINFULL = "$pwd/binFull"
     $BUILD = "$pwd/build"
 
@@ -23,7 +59,14 @@ try
     mkdir $build -ErrorAction SilentlyContinue
     cd $build
 
-    cmake ..\src\powershell-native
+    if ($cmakeGenerator)
+    {
+        cmake -G "$cmakeGenerator" ..\src\powershell-native
+    }
+    else
+    {
+        cmake ..\src\powershell-native
+    }
     msbuild powershell.sln
 
     cp -rec Debug\* $BINFULL