Debugger: provide breakpoint ranges for short lambdas

docs/release-notes/.FSharp.Compiler.Service/11.0.0.md

@@ -13,6 +13,7 @@
 ### Added
 
 * Add FSharpCodeCompletionOptions ([PR #19030](https://github.com/dotnet/fsharp/pull/19030))
+* Debugger: provide breakpoint ranges for short lambdas ([#19067](https://github.com/dotnet/fsharp/pull/19067))
 
 ### Changed
 

src/Compiler/Service/FSharpParseFileResults.fs

@@ -525,7 +525,6 @@ type FSharpParseFileResults(diagnostics: FSharpDiagnostic[], input: ParsedInput,
                         match expr with
                         | SynExpr.ArbitraryAfterError _
                         | SynExpr.LongIdent _
-                        | SynExpr.DotLambda _
                         | SynExpr.LibraryOnlyILAssembly _
                         | SynExpr.LibraryOnlyStaticOptimization _
                         | SynExpr.Null _
@@ -762,6 +761,8 @@ type FSharpParseFileResults(diagnostics: FSharpDiagnostic[], input: ParsedInput,
                             yield! walkExpr false e2
                             yield! walkExpr false e3
 
+                        | SynExpr.DotLambda(_, m, _) -> yield! checkRange m
+
                 ]
 
             // Process a class declaration or F# type declaration

tests/FSharp.Compiler.Service.Tests/BreakpointLocationTests.fs

@@ -0,0 +1,57 @@
+module FSharp.Compiler.Service.Tests.BreakpointLocationTests
+
+open FSharp.Compiler.Text
+open FSharp.Compiler.Text.Range
+open FSharp.Test.Assert
+open Xunit
+
+let assertBreakpointRange ((startLine, startCol), (endLine, endCol)) markedSource =
+    let context, parseResults = Checker.getParseResultsWithContext markedSource
+    let breakpointRange = parseResults.ValidateBreakpointLocation(context.CaretPos).Value
+
+    let startPos = Position.mkPos startLine startCol
+    let endPod = Position.mkPos endLine endCol
+    let expectedRange = mkFileIndexRange breakpointRange.FileIndex startPos endPod
+
+    breakpointRange |> shouldEqual expectedRange
+
+[<Fact>]
+let ``Let - Function - Body 01`` () =
+    assertBreakpointRange ((3, 4), (3, 5)) """
+let f () =
+    1{caret}
+"""
+
+[<Fact>]
+let ``Seq 01`` () =
+    assertBreakpointRange ((3, 4), (3, 5)) """
+do
+    1{caret}
+    2
+"""
+
+[<Fact>]
+let ``Seq 02`` () =
+    assertBreakpointRange ((4, 4), (4, 5)) """
+do
+    1
+    2{caret}
+"""
+
+[<Fact>]
+let ``Lambda 01`` () =
+    assertBreakpointRange ((2, 27), (2, 35)) """
+[""] |> List.map (fun s -> s.Lenght{caret}) 
+"""
+
+[<Fact>]
+let ``Dot lambda 01`` () =
+    assertBreakpointRange ((2, 17), (2, 25)) """
+[""] |> List.map _.Lenght{caret} 
+"""
+
+[<Fact>]
+let ``Dot lambda 02`` () =
+    assertBreakpointRange ((2, 17), (2, 36)) """
+[""] |> List.map _.ToString().Length{caret} 
+"""

tests/FSharp.Compiler.Service.Tests/Checker.fs

@@ -147,6 +147,11 @@ module Checker =
         let names = plid.QualifyingIdents @ [plid.PartialIdent]
         { SourceContext = context; Pos = context.CaretPos; PartialIdentifier = plid }
 
+    let getParseResultsWithContext (markedSource: string) =
+        let context = SourceContext.fromMarkedSource markedSource
+        let parseResults = getParseFileResults "Test.fsx" context.Source
+        context, parseResults
+
     let getCheckedResolveContext (markedSource: string) =
         let context = getResolveContext markedSource
         let _, checkResults = getParseAndCheckResults context.Source

tests/FSharp.Compiler.Service.Tests/Common.fs

@@ -188,7 +188,7 @@ let parseAndCheckScript50 (file, input) = parseAndCheckScriptWithOptions (file,
 let parseAndCheckScript70 (file, input) = parseAndCheckScriptWithOptions (file, input, [| "--langversion:7.0" |])
 let parseAndCheckScriptPreview (file, input) = parseAndCheckScriptWithOptions (file, input, [| "--langversion:preview" |])
 
-let parseSourceCode (name: string, code: string) =
+let getParseFileResults (name: string) (code: string) =
     let location = Path.Combine(Path.GetTempPath(),"test"+string(hash (name, code)))
     try Directory.CreateDirectory(location) |> ignore with _ -> ()
     let filePath = Path.Combine(location, name)
@@ -197,6 +197,10 @@ let parseSourceCode (name: string, code: string) =
     let options, _errors = checker.GetParsingOptionsFromCommandLineArgs(List.ofArray args)
     let parseResults = checker.ParseFile(filePath, SourceText.ofString code, options) |> Async.RunImmediate
     Range.setTestSource filePath code
+    parseResults
+
+let parseSourceCode (name: string, code: string) : ParsedInput =
+    let parseResults = getParseFileResults name code
     parseResults.ParseTree
 
 let matchBraces (name: string, code: string) =

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj

@@ -28,6 +28,7 @@
     <Compile Include="Checker.fs" />
     <Compile Include="TypeChecker\TypeCheckerRecoveryTests.fs" />
     <Compile Include="GeneratedCodeSymbolsTests.fs" />
+    <Compile Include="BreakpointLocationTests.fs" />
     <Compile Include="AssemblyReaderShim.fs" />
     <Compile Include="ModuleReaderCancellationTests.fs" />
     <Compile Include="EditorTests.fs" />