Fix #1218: Multiple namespaces in same file

Author: alfonsogarciacaro

build.fsx

@@ -196,6 +196,7 @@ Target "FableCLI" (fun _ ->
 Target "FableCoreJS" buildCoreJS
 Target "FableSplitter" buildSplitter
 Target "NUnitPlugin" buildNUnitPlugin
+Target "JsonConverter" buildJsonConverter
 Target "RunTestsJS" runTestsJS
 
 Target "PublishPackages" (fun () ->

src/dotnet/Fable.Compiler/FSharp2Fable.fs

@@ -953,7 +953,7 @@ type private DeclInfo(com, fileName) =
     let publicNameConflicts name =
         let conflicts = publicNames.Contains name
         if conflicts then
-            "Public types, modules or functions with same name at same level are not supported: " + name
+            "Public namespaces, modules, types or functions with same name at same level are not supported: " + name
             |> addError com fileName None
         else
             publicNames.Add name
@@ -1205,11 +1205,26 @@ and private transformDeclarations (com: IFableCompiler) ctx decls =
     declInfo.GetDeclarations(com)
 
 let private getRootModuleAndDecls decls =
+    let (|CommonNamespace|_|) = function
+        | (FSharpImplementationFileDeclaration.Entity(ent, subDecls))::restDecls
+            when ent.IsNamespace ->
+            let commonName = ent.CompiledName
+            (Some subDecls, restDecls) ||> List.fold (fun acc decl ->
+                match acc, decl with
+                | (Some subDecls), (FSharpImplementationFileDeclaration.Entity(ent, subDecls2)) ->
+                    if ent.CompiledName = commonName
+                    then Some(subDecls@subDecls2)
+                    else None
+                | _ -> None)
+            |> Option.map (fun subDecls -> ent, subDecls)
+        | _ -> None
     let rec getRootModuleAndDecls outerEnt decls =
         match decls with
         | [FSharpImplementationFileDeclaration.Entity (ent, decls)]
                 when ent.IsFSharpModule || ent.IsNamespace ->
             getRootModuleAndDecls (Some ent) decls
+        | CommonNamespace(ent, decls) ->
+            getRootModuleAndDecls (Some ent) decls
         | decls -> outerEnt, decls
     getRootModuleAndDecls None decls
 

tests/Main/Fable.Tests.fsproj

@@ -9,6 +9,7 @@
     <Compile Include="Util/Aether.fs" />
     <Compile Include="Util/Util.fs" />
     <Compile Include="Util/Util2.fs" />
+    <Compile Include="Util/Util3.fs" />
     <Compile Include="../../tests_external/Util3.fs" />
     <Compile Include="ApplicativeTests.fs" />
     <Compile Include="ArithmeticTests.fs" />

tests/Main/MiscTests.fs

@@ -137,6 +137,10 @@ let ``Type abbreviation in namespace compiles``() = // See #140
     let h = Util2.H(5)
     equal "5" h.Value
 
+[<Test>]
+let ``Multiple namespaces in same file work``() = // See #1218
+    A.C.Helper.Add5(9) |> equal 14
+
 let inline f x y = x + y
 
 [<Test>]
@@ -866,7 +870,7 @@ let ``While with isNone doesn't hang with Some ()``() =
     Trampoline.run (fun _ -> Trampoline.Break ()) () |> ignore
 
 
-let inline (|HasLength|) x = 
+let inline (|HasLength|) x =
   fun () -> (^a: (member Length: int) x)
 
 let inline length (HasLength f) = f()

tests/Main/Util/Util3.fs

@@ -0,0 +1,20 @@
+// Test that a file with multiple namespaces works, see #1218
+
+// Different namespace together with namespaces
+// sharing a prefix doesn't work
+// namespace My.Namespace
+
+// Duplicating namespaces doesn't work
+// namespace Fable.Tests.A.C
+
+// Empty namespaces work
+namespace Fable.Tests.A.D
+
+// Multiple mamespaces sharing prefix work
+namespace Fable.Tests.A.B
+type Helper =
+    static member Add2(x) = x + 2
+
+namespace Fable.Tests.A.C
+type Helper =
+    static member Add5(x) = Fable.Tests.A.B.Helper.Add2(x + 3)