Print some messages about locating KSPRoot

Author: drewcassidy

KSPCommon.props

@@ -52,20 +52,40 @@
   <PropertyGroup>
     <!-- Relative path that must exist for a path to be a valid KSP Install-->
     <KSPRootIdentifier>$(ManagedRelativePath)/Assembly-CSharp.dll</KSPRootIdentifier>
+    <KSPRootSource Condition="'$(KSPRoot)' != ''">property</KSPRootSource>
+  </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(KSPRoot)' == '' And '$(KSP_ROOT)' != '' ">
     <!-- Default KSPRoot to the "KSP_ROOT" environment variable if it exists -->
     <!-- Doing this skips any checks for a valid KSP install so be careful! -->
-    <KSPRoot Condition=" '$(KSPRoot)' == '' And '$(KSP_ROOT)' != '' ">$(KSP_ROOT)</KSPRoot>
+    <KSPRoot >$(KSP_ROOT)</KSPRoot>
+    <KSPRootSource>environment variable</KSPRootSource>
+  </PropertyGroup>
+  <ItemGroup>
+    <KSPRootCandidate Include="$(SolutionDir)KSP" source="solution directory"/>
+    <KSPRootCandidate Include="$(ReferencePath)" source="reference path"/>
+    <KSPRootCandidate Include="$(SteamKSPRoot)" source="steam"/>
+  </ItemGroup>
 
+  <PropertyGroup Condition=" '$(KSPRoot)' == '' And Exists('$(SolutionDir)KSP/$(KSPRootIdentifier)') ">
     <!-- Look for KSP install in Solution dir -->
-    <KSPRoot Condition=" '$(KSPRoot)' == '' And Exists('$(SolutionDir)KSP/$(KSPRootIdentifier)') ">$(SolutionDir)KSP</KSPRoot>
+    <KSPRoot >$(SolutionDir)KSP</KSPRoot>
+    <KSPRootSource>solution directory</KSPRootSource>
+  </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(KSPRoot)' == '' And Exists('$(ReferencePath)/$(KSPRootIdentifier)') ">
     <!-- Look for KSP install in ReferencePath -->
-    <KSPRoot Condition=" '$(KSPRoot)' == '' And Exists('$(ReferencePath)/$(KSPRootIdentifier)') ">$(ReferencePath)</KSPRoot>
+    <KSPRoot>$(ReferencePath)</KSPRoot>
+    <KSPRootSource>reference path</KSPRootSource>
+  </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(KSPRoot)' == '' And Exists('$(SteamKSPRoot)/$(KSPRootIdentifier)') ">
     <!-- Look for KSP steam install-->
-    <KSPRoot Condition=" '$(KSPRoot)' == '' And Exists('$(SteamKSPRoot)/$(KSPRootIdentifier)') ">$(SteamKSPRoot)</KSPRoot>
+    <KSPRoot>$(SteamKSPRoot)</KSPRoot>
+    <KSPRootSource>steam</KSPRootSource>
+  </PropertyGroup>
 
+  <PropertyGroup>
     <!-- Calculate ManagedPath -->
     <ManagedPath>$(KSPRoot)/$(ManagedRelativePath)</ManagedPath>
   </PropertyGroup>

KSPCommon.targets

@@ -10,9 +10,19 @@
 
   <!--Custom Targets-->
 
-  <Target Name="CheckForKSPRoot" BeforeTargets="ResolveReferences" Condition="'$(KSPRoot)' == ''">
-    <Error Text="KSPBuildTools was unable to find a KSP installation. Please set the ReferencePath or KSPRoot property in your csproj.user file to a valid KSP installation directory (the one with GameData in it)"/>
-    <Message Text="Found KSPRoot at $(KSPRoot)" Importance="low"/>
+  <Target Name="CheckForKSPRoot" BeforeTargets="ResolveReferences">
+    <Error Text="KSPBuildTools was unable to find a KSP installation. Please set the ReferencePath or KSPRoot property
+                 in your csproj.user file to a valid KSP installation directory (the one with GameData in it)
+
+                 See https://kspbuildtools.readthedocs.io/en/latest/msbuild/getting-started.html#locating-your-ksp-install for more information"
+           Condition="'$(KSPRoot)' == ''"/>
+    <ItemGroup>
+      <_KSPRootMessage Include="KSPRoot Candidates:"/>
+      <_KSPRootMessage Include="Candidate: %(KSPRootCandidate.source) from %(KSPRootCandidate.identity)"/>
+      <_KSPRootMessage Include="Chosen KSPRoot: $(KSPRoot) in $(KSPRootSource)" Condition="'$(KSPRoot)' != ''"/>
+    </ItemGroup>
+    <Message Text="@(_KSPRootMessage, '%0a')" Importance="normal"/>
+
   </Target>
 
   <!-- Copy output files to mod folder -->