Remove hardcoded signature dependency and add failing test.

Author: nojaf

tests/ParallelTypeCheckingTests/Code/DependencyResolution.fs

@@ -147,11 +147,7 @@ module internal DependencyResolution =
                 |> Array.exists (function Abbreviation.ModuleAbbreviation -> true | _ -> false))
 
         let trie = buildTrie nodes
-        
-        let fsiFiles =
-            nodes
-            |> Array.filter (fun f -> match f.File.AST with | ASTOrFsix.AST (ParsedInput.SigFile _) -> true | _ -> false)
-        
+
         let processFile (node : FileData) =
             let deps =
                 let fsiDep =
@@ -229,21 +225,13 @@ module internal DependencyResolution =
                     moduleRefs
                     |> Array.iter processRef
 
-                    // Force .fsi files to depend on all other (previous) .fsi files - avoids the issue of TcEnv being overriden  
-                    let additionalFsiDeps =
-                        if node.File.Name.EndsWith ".fsi" then
-                            nodes
-                        else
-                            [||]
-                    
                     // Collect files from all reachable TrieNodes
                     let deps =
                         reachable
                         |> Seq.collect (fun node -> node.Files)
                         // Assume that this file depends on all files that have any module abbreviations - this is probably unnecessary.
                         // TODO Handle module abbreviations in a better way
                         |> Seq.append filesWithModuleAbbreviations
-                        |> Seq.append additionalFsiDeps
                         |> Seq.append fsiDep
                         |> Seq.map (fun f -> f.File)
                         |> Seq.toArray

tests/ParallelTypeCheckingTests/Tests/TestCompilation.fs

@@ -115,12 +115,71 @@ open A
 """
         ] |> FProject.Make  CompileOutput.Library
 
+    let dependentSignatures =
+        [
+            "A.fsi", """
+module A
+
+type AType = class end
+"""
+            "A.fs", """
+module A
+
+type AType = class end
+"""
+            "B.fsi", """
+module B
+
+open A
+
+val b: AType -> unit
+"""
+            "B.fs", """
+module B
+
+open A
+
+let b (a:AType) = ()
+"""
+            "C.fsi", """
+module C
+
+type CType = class end
+"""
+            "C.fs", """
+module C
+
+type CType = class end
+"""
+            "D.fsi", """
+module D
+
+open A
+open C
+
+val d: CType -> unit 
+"""
+            "D.fs", """
+module D
+
+open A
+open B
+open C
+
+let d (c: CType) =
+    let a : AType = failwith "todo"
+    b a
+"""
+        ]
+        |> FProject.Make  CompileOutput.Library
+    
     let all =
         [
             encodeDecodeSimple
             diamondBroken1
             fsFsi
             emptyNamespace
+            dependentSignatures
         ]
 
 type Case =