From 4834a64773840024f3736638bf75b24271fc5dbb Mon Sep 17 00:00:00 2001
From: Daniel Cazzulino <daniel@cazzulino.com>
Date: Sat, 3 Oct 2020 16:35:54 -0300
Subject: [PATCH] Add prerequisite checks to avoid confusing users

Explicit build targets now check for the two requirements for
ThisAssembly: MSBuild 16.8+ or .NET SDK 5.0+ and C#.
---
 ThisAssembly.sln                              |  6 +++++
 .../ThisAssembly.AssemblyInfo.csproj          |  1 +
 .../ThisAssembly.Metadata.csproj              |  1 +
 .../ThisAssembly.Prerequisites.csproj         | 26 +++++++++++++++++++
 .../ThisAssembly.Prerequisites.props          |  7 +++++
 .../ThisAssembly.Prerequisites.targets        | 10 +++++++
 .../ThisAssembly.Project.csproj               |  1 +
 .../ThisAssembly.Strings.csproj               |  3 ++-
 8 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.csproj
 create mode 100644 src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.props
 create mode 100644 src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.targets

diff --git a/ThisAssembly.sln b/ThisAssembly.sln
index 38d7eeb4..d1b34b85 100644
--- a/ThisAssembly.sln
+++ b/ThisAssembly.sln
@@ -29,6 +29,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "workflows", "workflows", "{
 		.github\workflows\release.yml = .github\workflows\release.yml
 	EndProjectSection
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ThisAssembly.Prerequisites", "src\ThisAssembly.Prerequisites\ThisAssembly.Prerequisites.csproj", "{568E5150-84AD-4619-BEA3-AA5EDF084ABC}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -59,6 +61,10 @@ Global
 		{3E7158B5-BFEF-4416-8226-9096C7C98268}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{3E7158B5-BFEF-4416-8226-9096C7C98268}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{3E7158B5-BFEF-4416-8226-9096C7C98268}.Release|Any CPU.Build.0 = Release|Any CPU
+		{568E5150-84AD-4619-BEA3-AA5EDF084ABC}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{568E5150-84AD-4619-BEA3-AA5EDF084ABC}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{568E5150-84AD-4619-BEA3-AA5EDF084ABC}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{568E5150-84AD-4619-BEA3-AA5EDF084ABC}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
diff --git a/src/ThisAssembly.AssemblyInfo/ThisAssembly.AssemblyInfo.csproj b/src/ThisAssembly.AssemblyInfo/ThisAssembly.AssemblyInfo.csproj
index d80c6d14..31507279 100644
--- a/src/ThisAssembly.AssemblyInfo/ThisAssembly.AssemblyInfo.csproj
+++ b/src/ThisAssembly.AssemblyInfo/ThisAssembly.AssemblyInfo.csproj
@@ -33,6 +33,7 @@ on the `ThisAssembly.Info` class.
 
   <ItemGroup>
     <ProjectReference Include="../ThisAssembly.DesignTimeFix/ThisAssembly.DesignTimeFix.csproj" />
+    <ProjectReference Include="..\ThisAssembly.Prerequisites\ThisAssembly.Prerequisites.csproj" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/ThisAssembly.Metadata/ThisAssembly.Metadata.csproj b/src/ThisAssembly.Metadata/ThisAssembly.Metadata.csproj
index c3a923c6..1cc9eef7 100644
--- a/src/ThisAssembly.Metadata/ThisAssembly.Metadata.csproj
+++ b/src/ThisAssembly.Metadata/ThisAssembly.Metadata.csproj
@@ -64,6 +64,7 @@ F#:
 
   <ItemGroup>
     <ProjectReference Include="../ThisAssembly.DesignTimeFix/ThisAssembly.DesignTimeFix.csproj" />
+    <ProjectReference Include="..\ThisAssembly.Prerequisites\ThisAssembly.Prerequisites.csproj" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.csproj b/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.csproj
new file mode 100644
index 00000000..8fb2cc5a
--- /dev/null
+++ b/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.csproj
@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <PackBuildOutput>false</PackBuildOutput>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <PackageId>ThisAssembly.Prerequisites</PackageId>
+    <Description>Ensures that referencing project satisfies the prerequisites for ThisAssembly, namely:
+
+* MSBuild 16.8+: contains the Roslyn support for source generators
+* C# language: it's the only language supported by Roslyn source generators at the moment.
+</Description>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Remove="@(Compile)" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="NuGetizer" Version="0.4.1" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="all" />
+  </ItemGroup>
+
+</Project>
diff --git a/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.props b/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.props
new file mode 100644
index 00000000..9ccf5ec6
--- /dev/null
+++ b/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.props
@@ -0,0 +1,7 @@
+<Project>
+
+  <PropertyGroup>
+    <LangVersion>Preview</LangVersion>
+  </PropertyGroup>
+  
+</Project>
\ No newline at end of file
diff --git a/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.targets b/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.targets
new file mode 100644
index 00000000..112b5478
--- /dev/null
+++ b/src/ThisAssembly.Prerequisites/ThisAssembly.Prerequisites.targets
@@ -0,0 +1,10 @@
+<Project>
+
+  <Target Name="EnsureSourceGenerators" BeforeTargets="BeforeCompile;CoreCompile">
+    <Error Text="ThisAssembly requires MSBuild 16.8+ or .NET SDK 5.0+."
+           Condition="$([MSBuild]::VersionLessThan($(MSBuildVersion), '16.8'))" />
+    <Error Text="ThisAssembly uses Roslyn source generators, which are only supported in C# at the moment."
+           Condition="'$(Language)' != 'C#'" />
+  </Target>
+
+</Project>
diff --git a/src/ThisAssembly.Project/ThisAssembly.Project.csproj b/src/ThisAssembly.Project/ThisAssembly.Project.csproj
index 1f347a11..b438bc72 100644
--- a/src/ThisAssembly.Project/ThisAssembly.Project.csproj
+++ b/src/ThisAssembly.Project/ThisAssembly.Project.csproj
@@ -66,6 +66,7 @@ F#:
 
   <ItemGroup>
     <ProjectReference Include="../ThisAssembly.DesignTimeFix/ThisAssembly.DesignTimeFix.csproj" />
+    <ProjectReference Include="..\ThisAssembly.Prerequisites\ThisAssembly.Prerequisites.csproj" />
   </ItemGroup>
 
 </Project>
diff --git a/src/ThisAssembly.Strings/ThisAssembly.Strings.csproj b/src/ThisAssembly.Strings/ThisAssembly.Strings.csproj
index 45342984..f2438f0f 100644
--- a/src/ThisAssembly.Strings/ThisAssembly.Strings.csproj
+++ b/src/ThisAssembly.Strings/ThisAssembly.Strings.csproj
@@ -25,11 +25,12 @@ such as "Hello {name}".
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="all" />
     <PackageReference Include="Scriban" Version="2.1.4" PrivateAssets="all" />
 
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0-3.final" Pack="false"/>
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0-3.final" Pack="false" />
   </ItemGroup>
 
   <ItemGroup>
     <ProjectReference Include="../ThisAssembly.DesignTimeFix/ThisAssembly.DesignTimeFix.csproj" />
+    <ProjectReference Include="..\ThisAssembly.Prerequisites\ThisAssembly.Prerequisites.csproj" />
   </ItemGroup>
 
   <ItemGroup>