Additional notes on possible bugs in NuGet and dotnet

README.md

@@ -114,3 +114,22 @@ Therefore, to enable the strict control on compatibility, the csproj should cont
 but for some reasons I wasn't able to identify, the setting is just ignored.
 
 This seems to affect other warning codes as well. See the bug report on GitHub [Cannot disable NuGet warnings with dotnet 2.0](https://github.com/NuGet/Home/issues/5769)
+
+
+## Multiple compilations
+Astonishingly, 2 consecutive compilations of the same project produces a different number of warnings:
+
+![compilation1](pics/compile1.png)
+![compilation2](pics/compile2.png)
+
+Another strange behaviour is that the warnings `NU*` such as `NU1702` are just ignored by the settings:
+
+```xml
+<TreatWarningsAsErrors>True</TreatWarningsAsErrors>
+```
+
+A possible explaination is that those are NuGet warnings, differently from `CS*` warnings, which are build related: during the first build, `nuget restore` is invoked, which produces the first warning (ignored by `TreatWarningsAsErrors`, which is a MSBuild directive). During the second build, NuGet is not invoked anymore.
+
+This would be in line with what described by @xlegalles in [this comment](https://github.com/NuGet/Home/issues/5769#issuecomment-323295261).
+
+Finally, it seems that there are also other issues with multi-target projects (see the NuGet issue [Framework Conditioned warning properties are not respected for multi-targeting projects](https://github.com/NuGet/Home/issues/5712))

src/Console-Core2/Class1.cs

@@ -6,8 +6,8 @@ public class Class1
     {
     }
 
-//    class A
-//    {
-//        public virtual void Finalize() {}   // CS0465
-//    }
+    class A
+    {
+        public virtual void Finalize() {}   // CS0465
+    }
 }

src/Core2/Class1.cs

@@ -5,4 +5,10 @@ namespace Core2
     public class Class1
     {
     }
+
+    class A
+    {
+        public virtual void Finalize() {}   // CS0465
+    }
+
 }

src/Core2/Core2.csproj

@@ -1,13 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk">
-  <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
-  </PropertyGroup>
-  <PropertyGroup>
-    <WarningsAsErrors>NU1701,NU1702</WarningsAsErrors>
-  </PropertyGroup>
-  <ItemGroup>
-    <ProjectReference Include="..\Library472-old\Library472-old.csproj" />
-    <ProjectReference Include="..\Library472\Library472.csproj" />
-<!--    <ProjectReference Include="..\Library472\Library472.csproj" />-->
-  </ItemGroup>
+    <PropertyGroup>
+        <TargetFramework>netcoreapp2.0</TargetFramework>
+<!--        <NoWarn>1701;1702;1705;NU1702;NU1603;NU1605</NoWarn>-->
+    </PropertyGroup>
+    <PropertyGroup>
+              <TreatWarningsAsErrors>True</TreatWarningsAsErrors>
+        <WarningsAsErrors>NU1702;1702</WarningsAsErrors>
+    </PropertyGroup>
+    <ItemGroup>
+        <ProjectReference Include="..\Library472-old\Library472-old.csproj"/>
+        <ProjectReference Include="..\Library472\Library472.csproj"/>
+    </ItemGroup>
 </Project>