Simplified repro for #2679

tests/service/ProjectAnalysisTests.fs

@@ -4851,3 +4851,21 @@ let ``Test request for parse and check doesn't check whole project`` () =
 
     ()
 
+[<Test>]
+// Simplified repro for https://github.com/Microsoft/visualfsharp/issues/2679
+let ``add files with same name from different folders`` () = 
+    let fileNames =
+        [ __SOURCE_DIRECTORY__ + "/data/samename/folder1/a.fs"
+          __SOURCE_DIRECTORY__ + "/data/samename/folder2/a.fs" ]
+    let projFileName = __SOURCE_DIRECTORY__ + "/data/samename/tempet.fsproj"
+    let args = mkProjectCommandLineArgs ("test.dll", fileNames)
+    let options = checker.GetProjectOptionsFromCommandLineArgs (projFileName, args)
+    let wholeProjectResults = checker.ParseAndCheckProject(options) |> Async.RunSynchronously
+    let errors =
+        wholeProjectResults.Errors
+        |> Array.filter (fun x -> x.Severity = FSharpErrorSeverity.Error)
+    if errors.Length > 0 then
+        printfn "add files with same name from different folders"
+        for err in errors do
+            printfn "ERROR: %s" err.Message
+    shouldEqual 0 errors.Length

tests/service/data/samename/folder1/a.fs

@@ -0,0 +1,5 @@
+namespace tempet
+
+module SayA =
+    let hello name =
+        printfn "Hello %s" name

tests/service/data/samename/folder2/a.fs

@@ -0,0 +1,5 @@
+namespace tempet
+
+module SayA =
+    let hello name =
+        printfn "Hello %s" name

tests/service/data/samename/tempet.fsproj

@@ -0,0 +1,13 @@
+<Project Sdk="FSharp.NET.Sdk;Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>netstandard1.6</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="folder1/a.fs" />
+    <Compile Include="folder2/a.fs" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="FSharp.Core" Version="4.1.*" />
+    <PackageReference Include="FSharp.NET.Sdk" Version="1.0.*" PrivateAssets="All" />
+  </ItemGroup>
+</Project>