feat(all): support suppressing warnings via // fable-disable comments

src/Fable.Cli/Main.fs

@@ -15,7 +15,7 @@ open Fable.Transforms.State
 open Fable.Compiler.ProjectCracker
 open Fable.Compiler.Util
 
-module private Util =
+module Util =
     type PathResolver with
 
         static member Dummy =
@@ -78,10 +78,18 @@ module private Util =
                 | Severity.Error -> "error"
                 | Severity.Info -> "info"
 
+            // MSBuild-style `<severity> <tag> <code>`: without the code there is no way to
+            // discover what to put in a `// fable-disable-line` comment, and rendering it here
+            // also makes Fable warnings parseable by IDEs and MSBuild loggers.
+            let tag =
+                match log.Code with
+                | Some code -> $"%s{log.Tag} %s{code}"
+                | None -> log.Tag
+
             match log.Range with
             | Some r ->
-                $"%s{file}(%i{r.start.line},%i{r.start.column}): (%i{r.``end``.line},%i{r.``end``.column}) %s{severity} %s{log.Tag}: %s{log.Message}"
-            | None -> $"%s{file}(1,1): %s{severity} %s{log.Tag}: %s{log.Message}"
+                $"%s{file}(%i{r.start.line},%i{r.start.column}): (%i{r.``end``.line},%i{r.``end``.column}) %s{severity} %s{tag}: %s{log.Message}"
+            | None -> $"%s{file}(1,1): %s{severity} %s{tag}: %s{log.Message}"
 
     let logErrors rootDir (logs: LogEntry seq) =
         logs
@@ -356,6 +364,18 @@ type FsWatcher(delayMs: int) =
 
 type ProjectCracked(cliArgs: CliArgs, crackerResponse: CrackerResponse, sourceFiles: Fable.Compiler.File array) =
 
+    let sourceReader = lazy (snd (Fable.Compiler.File.MakeSourceReader sourceFiles))
+
+    // Shared by every file of the project: a warning can point at any file (inlined calls) and
+    // files compile in parallel. A new ProjectCracked is built on every watch rebuild, so this
+    // never outlives the source it was computed from.
+    let warningSuppression =
+        lazy
+            (WarningSuppression.Resolver.FromCompilerOptions(
+                crackerResponse.ProjectOptions.OtherOptions,
+                sourceReader.Value
+            ))
+
     member _.CliArgs = cliArgs
     member _.ProjectFile = cliArgs.ProjectFile
     member _.FableOptions = cliArgs.CompilerOptions
@@ -392,9 +412,32 @@ type ProjectCracked(cliArgs: CliArgs, crackerResponse: CrackerResponse, sourceFi
             fableLibDir,
             crackerResponse.OutputType,
             ?outDir = cliArgs.OutDir,
-            ?watchDependencies = watchDependencies
+            ?watchDependencies = watchDependencies,
+            warningSuppression = warningSuppression.Value
         )
 
+    /// Problems with the `fable-disable` directives themselves (typo'd codes, directives that
+    /// suppress nothing). Only valid once every file has been compiled, since a directive in one
+    /// file can be what suppresses a warning raised while compiling another.
+    member _.DirectiveDiagnostics(files: string seq) =
+        warningSuppression.Value.GetDiagnostics(files)
+        |> List.map (fun (file, d) ->
+            let pos: Position =
+                {
+                    line = d.Line
+                    column = 0
+                }
+
+            LogEntry.Make(
+                Severity.Warning,
+                d.Message,
+                fileName = file,
+                range = SourceLocation.Create(pos, pos, file),
+                code = d.Code
+            )
+        )
+        |> Array.ofList
+
     member _.MapSourceFiles(f) =
         ProjectCracked(cliArgs, crackerResponse, Array.map f sourceFiles)
 
@@ -1444,6 +1487,11 @@ let private compilationCycle (state: State) (changes: ISet<string>) =
                         Array.append logs [| log |], deps
                 )
 
+            // Every file is compiled by now, so a directive that still hasn't suppressed anything
+            // really is unused - checking earlier would flag directives that only ever fire for a
+            // warning raised while some later file was being compiled.
+            let logs = Array.append logs (projCracked.DirectiveDiagnostics filesToCompile)
+
             let state =
                 { state with
                     PendingFiles = [||]

src/Fable.Compiler/Library.fs

@@ -180,7 +180,12 @@ module CodeServices =
                     opts,
                     fableLibDir,
                     crackerResponse.OutputType,
-                    ?outDir = cliArgs.OutDir
+                    ?outDir = cliArgs.OutDir,
+                    warningSuppression =
+                        WarningSuppression.Resolver.FromCompilerOptions(
+                            crackerResponse.ProjectOptions.OtherOptions,
+                            sourceReader
+                        )
                 )
 
             // TODO: make it configurable if FableTransforms.transformFile is applied?
@@ -220,6 +225,9 @@ module CodeServices =
                     async {
                         let fableLibDir = Path.getRelativePath currentFile crackerResponse.FableLibDir
 
+                        // No `warningSuppression`: this overload is handed an already type-checked
+                        // project rather than a `SourceReader`, so there is no source to scan for
+                        // `// fable-disable` comments. Not a bug, just a limitation of the entry point.
                         let compiler: Compiler =
                             CompilerImpl(
                                 currentFile,
@@ -305,6 +313,12 @@ module CodeServices =
 
             let opts = cliArgs.CompilerOptions
 
+            let warningSuppression =
+                WarningSuppression.Resolver.FromCompilerOptions(
+                    crackerResponse.ProjectOptions.OtherOptions,
+                    sourceReader
+                )
+
             let! compiledFiles =
                 dependentFiles
                 |> Array.filter (fun filePath -> not (filePath.EndsWith(".fsi", StringComparison.Ordinal)))
@@ -319,7 +333,8 @@ module CodeServices =
                                 opts,
                                 fableLibDir,
                                 crackerResponse.OutputType,
-                                ?outDir = cliArgs.OutDir
+                                ?outDir = cliArgs.OutDir,
+                                warningSuppression = warningSuppression
                             )
 
                         let outputPath = Path.ChangeExtension(currentFile, ".js")

src/Fable.Transforms/Babel/Fable2Babel.fs

@@ -4987,8 +4987,8 @@ module Compiler =
 
             member _.AddWatchDependency(fileName) = com.AddWatchDependency(fileName)
 
-            member _.AddLog(msg, severity, ?range, ?fileName: string, ?tag: string) =
-                com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag)
+            member _.AddLog(msg, severity, ?range, ?fileName: string, ?tag: string, ?code: string) =
+                com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag, ?code = code)
 
     let makeCompiler com = BabelCompiler(com)
 

src/Fable.Transforms/Beam/Fable2Beam.fs

@@ -3760,8 +3760,8 @@ let transformFile (com: Fable.Compiler) (file: File) : Beam.ErlModule =
             member _.GetInlineExpr(key) = com.GetInlineExpr(key)
             member _.AddWatchDependency(file) = com.AddWatchDependency(file)
 
-            member _.AddLog(msg, severity, ?range, ?fileName, ?tag) =
-                com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag)
+            member _.AddLog(msg, severity, ?range, ?fileName, ?tag, ?code) =
+                com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag, ?code = code)
         }
 
     let forms =

src/Fable.Transforms/Dart/Fable2Dart.fs

@@ -3117,8 +3117,8 @@ module Compiler =
 
             member _.AddWatchDependency(fileName) = com.AddWatchDependency(fileName)
 
-            member _.AddLog(msg, severity, ?range, ?fileName: string, ?tag: string) =
-                com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag)
+            member _.AddLog(msg, severity, ?range, ?fileName: string, ?tag: string, ?code: string) =
+                com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag, ?code = code)
 
     let makeCompiler com = DartCompiler(com)
 

src/Fable.Transforms/Dart/Replacements.fs

@@ -1395,7 +1395,7 @@ let strings (com: ICompiler) (ctx: Context) r t (i: CallInfo) (thisArg: Expr opt
     | "GetEnumerator", Some c, _ -> stringToCharSeq c |> getEnumerator com r t |> Some
     | ("Contains" | "StartsWith" | "EndsWith" as meth), Some c, arg :: _ ->
         if List.isMultiple args then
-            addWarning com ctx.InlinePath r $"String.%s{meth}: second argument is ignored"
+            WarningCodes.stringComparisonIgnored |> addWarningWithCode com ctx.InlinePath r
 
         Helper.InstanceCall(c, Naming.lowerFirst meth, t, [ arg ], ?loc = r) |> Some
     | ReplaceName [ "ToUpper", "toUpperCase"
@@ -2085,19 +2085,22 @@ let parseNum (com: ICompiler) (ctx: Context) r t (i: CallInfo) (thisArg: Expr op
         let intConst = int System.Globalization.NumberStyles.Integer
 
         if style <> hexConst && style <> intConst then
-            $"%s{i.DeclaringEntityFullName}.%s{meth}(): NumberStyle %d{style} is ignored"
-            |> addWarning com ctx.InlinePath r
+            WarningCodes.numberStylesIgnored style
+            |> addWarningWithCode com ctx.InlinePath r
 
         let acceptedArgs =
             if meth = "Parse" then
                 2
             else
                 3
 
-        if List.length args > acceptedArgs then
+        match List.tryItem acceptedArgs args with
+        // InvariantCulture asks for exactly what Fable does, so there is nothing to report.
+        | None
+        | Some InvariantCulture -> ()
+        | Some _ ->
             // e.g. Double.Parse(string, style, IFormatProvider) etc.
-            $"%s{i.DeclaringEntityFullName}.%s{meth}(): provider argument is ignored"
-            |> addWarning com ctx.InlinePath r
+            WarningCodes.formatProviderIgnored |> addWarningWithCode com ctx.InlinePath r
 
         parseCall meth str args style
     | ("Parse" | "TryParse") as meth, str :: _ ->
@@ -2107,10 +2110,13 @@ let parseNum (com: ICompiler) (ctx: Context) r t (i: CallInfo) (thisArg: Expr op
             else
                 2
 
-        if List.length args > acceptedArgs then
+        match List.tryItem acceptedArgs args with
+        // InvariantCulture asks for exactly what Fable does, so there is nothing to report.
+        | None
+        | Some InvariantCulture -> ()
+        | Some _ ->
             // e.g. Double.Parse(string, IFormatProvider) etc.
-            $"%s{i.DeclaringEntityFullName}.%s{meth}(): provider argument is ignored"
-            |> addWarning com ctx.InlinePath r
+            WarningCodes.formatProviderIgnored |> addWarningWithCode com ctx.InlinePath r
 
         let style = int System.Globalization.NumberStyles.Any
         parseCall meth str args style
@@ -2708,8 +2714,7 @@ let convert (com: ICompiler) (ctx: Context) r t (i: CallInfo) (_: Expr option) (
     | "ToBase64String"
     | "FromBase64String" ->
         if not (List.isSingle args) then
-            $"Convert.%s{Naming.upperFirst i.CompiledName} only accepts one single argument"
-            |> addWarning com ctx.InlinePath r
+            WarningCodes.base64ArgumentsIgnored |> addWarningWithCode com ctx.InlinePath r
 
         Helper.LibCall(
             com,
@@ -2858,11 +2863,33 @@ let dates (com: ICompiler) (ctx: Context) r t (i: CallInfo) (thisArg: Expr optio
 
         Helper.InstanceCall(thisArg.Value, meth, t, args, ?loc = r) |> Some
     | meth ->
+        // Drops the IFormatProvider (and DateTimeStyles, where present), warning once per
+        // discarded argument. `Parse arg` with no extra argument discards nothing.
         let args =
+            // Passing InvariantCulture asks for exactly what Fable does, so nothing to report.
+            let warnProvider culture =
+                match culture with
+                | InvariantCulture -> ()
+                | _ -> WarningCodes.formatProviderIgnored |> addWarningWithCode com ctx.InlinePath r
+
+            let warnStyles styles =
+                match styles with
+                | NumberConst(NumberValue.Int32 0, _) -> () // DateTimeStyles.None: no special handling
+                | _ -> WarningCodes.dateTimeStylesIgnored |> addWarningWithCode com ctx.InlinePath r
+
             match meth, args with
-            // Ignore IFormatProvider
+            | "Parse", arg :: culture :: styles :: _ ->
+                warnProvider culture
+                warnStyles styles
+                [ arg ]
+            | "Parse", arg :: culture :: _ ->
+                warnProvider culture
+                [ arg ]
             | "Parse", arg :: _ -> [ arg ]
-            | "TryParse", input :: _culture :: _styles :: defVal :: _ -> [ input; defVal ]
+            | "TryParse", input :: culture :: styles :: defVal :: _ ->
+                warnProvider culture
+                warnStyles styles
+                [ input; defVal ]
             | _ -> args
 
         let meth = Naming.removeGetSetPrefix meth |> Naming.lowerFirst

src/Fable.Transforms/FSharp2Fable.fs

@@ -2857,8 +2857,8 @@ type FableCompiler(com: Compiler) =
         member _.GetInlineExpr(fullName) = com.GetInlineExpr(fullName)
         member _.AddWatchDependency(fileName) = com.AddWatchDependency(fileName)
 
-        member _.AddLog(msg, severity, ?range, ?fileName: string, ?tag: string) =
-            com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag)
+        member _.AddLog(msg, severity, ?range, ?fileName: string, ?tag: string, ?code: string) =
+            com.AddLog(msg, severity, ?range = range, ?fileName = fileName, ?tag = tag, ?code = code)
 
 
 let rec attachClassMembers (com: FableCompiler) =

src/Fable.Transforms/Fable.Transforms.fsproj

@@ -5,6 +5,8 @@
     <Compile Include="Global/Metadata.fs" />
     <Compile Include="Global/Prelude.fs" />
     <Compile Include="Global/Compiler.fs" />
+    <Compile Include="Global/WarningCodes.fs" />
+    <Compile Include="Global/WarningSuppression.fs" />
     <Compile Include="Global/Naming.fs" />
     <Compile Include="Python/Prelude.fs" />
     <Compile Include="MonadicTrampoline.fs" />

src/Fable.Transforms/Global/Compiler.fs

@@ -86,7 +86,8 @@ type Compiler =
     abstract AddWatchDependency: file: string -> unit
 
     abstract AddLog:
-        msg: string * severity: Severity * ?range: SourceLocation * ?fileName: string * ?tag: string -> unit
+        msg: string * severity: Severity * ?range: SourceLocation * ?fileName: string * ?tag: string * ?code: string ->
+            unit
 
 type InlineExprLazy(f: Compiler -> InlineExpr) =
     let mutable value: InlineExpr voption = ValueNone