Error: An implementation of file has already been given

[et1975]

Description

Same file name across different project references causes the error:

Fable loader sent: fable-elmish/samples/react/navigation/app.fsproj
F# PROJECT: fable-elmish/samples/react/navigation/app.fsproj
   fable-elmish/samples/react/node_modules/fable-powerpack/src/Result.fs
   fable-elmish/samples/react/node_modules/fable-powerpack/src/Promise.fs
   fable-elmish/samples/react/node_modules/fable-powerpack/src/PromiseSeq/Type.fs
   fable-elmish/samples/react/node_modules/fable-powerpack/src/PromiseSeq/Module.fs
   fable-elmish/samples/react/node_modules/fable-powerpack/src/PromiseSeq/Extensions.fs
   fable-elmish/samples/react/node_modules/fable-powerpack/src/Fetch.fs
   fable-elmish/samples/react/node_modules/fable-powerpack/src/IndexedDB.fs
   fable-elmish/samples/react/node_modules/fable-react/Fable.Import.React.fs
   fable-elmish/samples/react/node_modules/fable-react/Fable.Helpers.React.fs
   fable-elmish/samples/react/node_modules/fable-elmish/prelude.fs
   fable-elmish/samples/react/node_modules/fable-elmish/cmd.fs
   fable-elmish/samples/react/node_modules/fable-elmish/program.fs
   fable-elmish/samples/react/node_modules/fable-elmish-react/common.fs
   fable-elmish/samples/react/node_modules/fable-elmish-react/react.fs
   fable-elmish/samples/react/node_modules/fable-elmish-react/react-native.fs
   fable-elmish/samples/react/node_modules/fable-elmish-browser/prelude.fs
   fable-elmish/samples/react/node_modules/fable-elmish-browser/parser.fs
   fable-elmish/samples/react/node_modules/fable-elmish-browser/navigation.fs
   fable-elmish/samples/react/node_modules/fable-elmish-debugger/Fable.Import.RemoteDev.fs
   fable-elmish/samples/react/node_modules/fable-elmish-debugger/debugger.fs
   fable-elmish/samples/react/navigation/app.fs
Parsing F# project...
F# project contains errors:
fable-elmish/samples/react/node_modules/fable-elmish-browser/prelude.fs(L4,0) : error FSHARP: An implementation of the file or module 'Prelude' has already been given

Repro code

in fable-elmish/samples/react:

yarn install
cd navigation
dotnet restore
dotnet fable npm-run start

Expected and actual results

Expect it to compile.

Related information

• fable-compiler version: 1.0.0-narumi-907
• fable-core version: 1.0.0-narumi-906
• Operating system: OSX

[alfonsogarciacaro]

No good, Fable is merging all files in a single project (that's the only way to get the full AST). We could try to avoid that or change the file names somehow, but it'd be a considerable amount of work. Ideally this should be fixed in the compiler, I'm taking shots in the dark here: dotnet/fsharp#2728

[alfonsogarciacaro]

Original issue in F# compiler dotnet/fsharp#2679

[alfonsogarciacaro]

A coup d'état attempt and @forki's help has been necessary to fix this, but it finally seems to be working now :)

@et1975 @MangelMaxime Could you please update to latest dotnet-fable (use dotnet restore --no-cache) and try again?

[MangelMaxime]

Thanks @forki and @alfonsogarciacaro this solved the problem we were facing when using Elmish + elmish-browser-navigation 👏 👏 👏