FavourIgnoreOverLetWild: implement suggestions

Co-authored-by: webwarrior <reg@webwarrior.ws>

Author: Mersho

src/FSharpLint.Core/Rules/Conventions/Binding/FavourIgnoreOverLetWild.fs

@@ -7,25 +7,39 @@ open FSharp.Compiler.Syntax
 open FSharpLint.Framework.Ast
 open FSharpLint.Framework.Rules
 
-let private checkForBindingToAWildcard pattern range =
+let private checkForBindingToAWildcard pattern range fileContent (expr: SynExpr) letBindingRange =
     let rec findWildAndIgnoreParens = function
         | SynPat.Paren(pattern, _) -> findWildAndIgnoreParens pattern
         | SynPat.Wild(_) -> true
         | _ -> false
 
-    if findWildAndIgnoreParens pattern then
-        { Range = range
-          Message = Resources.GetString("RulesFavourIgnoreOverLetWildError")
-          SuggestedFix = None
-          TypeChecks = [] } |> Array.singleton
-    else
-        Array.empty
+    match ExpressionUtilities.tryFindTextOfRange expr.Range fileContent with
+    | Some exprText -> 
+        if findWildAndIgnoreParens pattern then
+            { Range = range
+              Message = Resources.GetString("RulesFavourIgnoreOverLetWildError")
+              SuggestedFix = Some (lazy (Some({ FromRange = letBindingRange
+                                                FromText = fileContent
+                                                ToText = sprintf "(%s) |> ignore" exprText })))
+              TypeChecks = [] } |> Array.singleton
+        else
+            Array.empty
+    | None -> Array.empty
 
 let private runner (args:AstNodeRuleParams) =
     match args.AstNode with
-    | AstNode.Binding(SynBinding(_, _, _, _, _, _, _, pattern, _, _, range, _, _))
-            when Helper.Binding.isLetBinding args.NodeIndex args.SyntaxArray ->
-        checkForBindingToAWildcard pattern range
+    | AstNode.Binding(SynBinding(_, _, _, _, _, _, _, pattern, _, expr, range, _, _)) ->
+        let bindingRange  = 
+            match args.GetParents(args.NodeIndex) with
+            | AstNode.ModuleDeclaration(SynModuleDecl.Let(_, _, range)) :: _
+            | AstNode.Expression(SynExpr.LetOrUse(_, false, _, _, range, _)) :: _ -> 
+                Some(range)
+            | _ -> None
+
+        match bindingRange with
+        | Some letBindingRange -> 
+            checkForBindingToAWildcard pattern range args.FileContent expr letBindingRange
+        | None -> Array.empty
     | _ -> Array.empty
 
 /// Checks if any code uses 'let _ = ...' and suggests to use the ignore function.