Completion: fix qualified completion in sequence expressions

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -17,6 +17,7 @@
 * Add missing nullable-metadata for C# consumers of records,exceptions and DU subtypes generated from F# code. [PR #18079](https://github.com/dotnet/fsharp/pull/18079)
 * Fix a race condition in file book keeping in the compiler service ([#18008](https://github.com/dotnet/fsharp/pull/18008))
 * Fix trimming '%' characters when lowering interpolated string to a concat call [PR #18123](https://github.com/dotnet/fsharp/pull/18123)
+* Completion: fix qualified completion in sequence expressions [PR #18111](https://github.com/dotnet/fsharp/pull/18111)
 * Symbols: try to use ValReprInfoForDisplay in Mfv.CurriedParameterGroups ([PR #18124](https://github.com/dotnet/fsharp/pull/18124))
 * Shim/file system: fix leaks of the shim [PR #18144](https://github.com/dotnet/fsharp/pull/18144)
 

src/Compiler/Service/ServiceParseTreeWalk.fs

@@ -388,12 +388,6 @@ module SyntaxTraversal =
                 seq {
                     match expr with
                     | SynExpr.Sequential(expr1 = expr1; expr2 = SynExpr.Sequential _ as expr2) ->
-                        // It's a nested sequential expression.
-                        // Visit it, but make defaultTraverse do nothing,
-                        // since we're going to traverse its descendants ourselves.
-                        yield dive expr expr.Range (fun expr -> visitor.VisitExpr(path, traverseSynExpr path, (fun _ -> None), expr))
-
-                        // Now traverse its descendants.
                         let path = SyntaxNode.SynExpr expr :: path
                         yield dive expr1 expr1.Range (traverseSynExpr path)
                         yield! traverseSequentials path expr2

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

@@ -97,3 +97,40 @@ let ``Type decl - Record - Field type 01`` () =
 type Record = { Field:  }
 """
     assertHasItemWithNames ["string"] info
+
+
+[<Fact>]
+let ``Expr - Qualifier 01`` () =
+    let info =
+        getCompletionInfo "s.Trim(). " (3, 13) """
+let f (s: string) =
+    s.Trim().
+    s.Trim()
+    s.Trim()
+    ()
+"""
+    assertHasItemWithNames ["Length"] info
+
+[<Fact>]
+let ``Expr - Qualifier 02`` () =
+    let info =
+        getCompletionInfo "s.Trim(). " (4, 13) """
+let f (s: string) =
+    s.Trim()
+    s.Trim().
+    s.Trim()
+    ()
+"""
+    assertHasItemWithNames ["Length"] info
+
+[<Fact>]
+let ``Expr - Qualifier 03`` () =
+    let info =
+        getCompletionInfo "s.Trim(). " (5, 13) """
+let f (s: string) =
+    s.Trim()
+    s.Trim()
+    s.Trim().
+    ()
+"""
+    assertHasItemWithNames ["Length"] info