Add trivia and service test

Author: tboby

src/Compiler/Checking/CheckExpressions.fs

@@ -5467,7 +5467,7 @@ and TcExprUndelayed (cenv: cenv) (overallTy: OverallTy) env tpenv (synExpr: SynE
         TcNonControlFlowExpr env <| fun env ->
         CallExprHasTypeSink cenv.tcSink (m, env.NameEnv, overallTy.Commit, env.AccessRights)
         TcConstExpr cenv overallTy env m tpenv synConst
-    | SynExpr.DotLambda (synExpr, m) ->
+    | SynExpr.DotLambda (synExpr, m, _) ->
         let unaryArg = mkSynId m (cenv.synArgNameGenerator.New())
         let svar = mkSynCompGenSimplePatVar unaryArg
         let pushedExpr = pushUnaryArg synExpr unaryArg

src/Compiler/SyntaxTree/SyntaxTree.fs

@@ -611,7 +611,7 @@ type SynExpr =
 
     | DotGet of expr: SynExpr * rangeOfDot: range * longDotId: SynLongIdent * range: range
 
-    | DotLambda of expr: SynExpr * range: range
+    | DotLambda of expr: SynExpr * range: range * trivia: SynExprDotLambdaTrivia
 
     | DotSet of targetExpr: SynExpr * longDotId: SynLongIdent * rhsExpr: SynExpr * range: range
 

src/Compiler/SyntaxTree/SyntaxTree.fsi

@@ -767,7 +767,7 @@ type SynExpr =
     | DotGet of expr: SynExpr * rangeOfDot: range * longDotId: SynLongIdent * range: range
 
     /// F# syntax: _.ident.ident
-    | DotLambda of expr: SynExpr * range: range
+    | DotLambda of expr: SynExpr * range: range * trivia: SynExprDotLambdaTrivia
 
     /// F# syntax: expr.ident...ident <- expr
     | DotSet of targetExpr: SynExpr * longDotId: SynLongIdent * rhsExpr: SynExpr * range: range

src/Compiler/SyntaxTree/SyntaxTrivia.fs

@@ -75,6 +75,13 @@ type SynExprLambdaTrivia =
 
     static member Zero: SynExprLambdaTrivia = { ArrowRange = None }
 
+[<NoEquality; NoComparison>]
+type SynExprDotLambdaTrivia =
+    {
+        UnderscoreRange : range
+        DotRange : range
+    }
+
 [<NoEquality; NoComparison>]
 type SynExprLetOrUseTrivia = { InKeyword: range option }
 

src/Compiler/SyntaxTree/SyntaxTrivia.fsi

@@ -119,6 +119,14 @@ type SynExprLambdaTrivia =
 
     static member Zero: SynExprLambdaTrivia
 
+/// Represents additional information for SynExpr.DotLambda
+[<NoEquality; NoComparison>]
+type SynExprDotLambdaTrivia =
+    {
+        UnderscoreRange : range
+        DotRange : range
+    }
+    
 /// Represents additional information for SynExpr.LetOrUse
 [<NoEquality; NoComparison>]
 type SynExprLetOrUseTrivia =

src/Compiler/pars.fsy

@@ -4307,9 +4307,11 @@ argExpr:
 
 atomicExpr:
   | UNDERSCORE DOT atomicExpr %prec dot_lambda
-      { let arg1 = lhs parseState
-        let arg2, hpa = $3
-        SynExpr.DotLambda(arg2, arg2.Range), false }
+      { let arg1 = rhs parseState 1
+        let arg2 = rhs parseState 2
+        let arg3, hpa = $3
+        let trivia: SynExprDotLambdaTrivia = { UnderscoreRange = arg1; DotRange = arg2 }
+        SynExpr.DotLambda(arg3, unionRanges arg1 arg3.Range, trivia), false }
 
   | atomicExpr HIGH_PRECEDENCE_BRACK_APP atomicExpr
       { let arg1, _ = $1 

tests/service/SyntaxTreeTests/ExpressionTests.fs

@@ -4,15 +4,6 @@ open FSharp.Compiler.Service.Tests.Common
 open FSharp.Compiler.Syntax
 open FSharp.Compiler.SyntaxTrivia
 open NUnit.Framework
-
-open Xunit
-// [<Fact>]
-// let ``Thomas`` () =
-    // let ast = """_.ToString.ToString "b" """ |> getParseResults
-    // let ast = """_.x""" |> getParseResults
-    // let ast = """_.x()""" |> getParseResults
-    // Assert.Fail (ast.ToString())
-    
 [<Test>]
 let ``SynExpr.Do contains the range of the do keyword`` () =
     let ast = """let a =
@@ -502,3 +493,29 @@ type CFoo() =
         assertRange (7,4) (7, 67) m
     | _ -> Assert.Fail $"Could not get valid AST, got {ast}"
 
+[<Test>]
+let ``SynExpr.DotLambda has correct ranges and trivia`` () =
+    let ast =
+        getParseResults """
+let e1 : obj [] -> string = _(*test*).(*test*)[5].ToString()
+"""
+
+    match ast with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Let(bindings =
+                        [SynBinding.SynBinding(expr =
+                            SynExpr.Typed(expr =
+                                SynExpr.DotLambda(
+                                    SynExpr.App(range = innerRange),
+                                    dlRange,
+                                    { UnderscoreRange = urange; DotRange = dRange }
+                                    )))])
+                ])
+            ])) ->
+        assertRange (2, 28) (2, 60) dlRange
+        assertRange (2, 28) (2, 29) urange
+        assertRange (2, 37) (2, 38) dRange
+        assertRange (2, 46) (2, 60) innerRange
+        Assert.Pass()
+    | _ -> Assert.Fail $"Could not get valid AST, got {ast}"