Resolve Go To Definition targets through the workspace's current solution

docs/release-notes/.VisualStudio/18.vNext.md

@@ -14,6 +14,7 @@
 * Make Alt+F1 (momentary toggle) work for inlay hints. ([PR #19421](https://github.com/dotnet/fsharp/pull/19421))
 * Fix doubled F# diagnostics in tooltips. ([Issue #16360](https://github.com/dotnet/fsharp/issues/16360))
 * Fix `NotSupportedException` in the memory-mapped-file optimization when copying `ReadOnlyMemory` into `MemoryMappedFileViewStream`. ([Issue #20263](https://github.com/dotnet/fsharp/issues/20263))
+* Go To Definition on a symbol declared in another project of the solution no longer opens a generated signature when the origin document comes from a solution snapshot that predates that project's documents: navigation, Find All References and Rename now look the target up in the workspace's current solution as well. ([PR #20462](https://github.com/dotnet/fsharp/pull/20462))
 
 ### Changed
 

vsintegration/src/FSharp.Editor/Common/CodeAnalysisExtensions.fs

@@ -117,3 +117,32 @@ type Solution with
         | Some projectId -> self.TryGetDocumentIdFromFSharpRange(range, projectId)
         | None -> self.TryGetDocumentIdFromFSharpRange range
         |> Option.map self.GetDocument
+
+type Document with
+
+    /// Runs a lookup against this document's solution and, when it finds nothing, against the
+    /// workspace's current solution: the document may come from a snapshot taken before every
+    /// project of the solution finished loading.
+    member document.TryFindInSolutions(find: Solution -> 'T voption) =
+        match find document.Project.Solution with
+        | ValueSome found -> ValueSome found
+        | ValueNone -> find document.Project.Solution.Workspace.CurrentSolution
+
+    /// Every document with the file path, from whichever project includes it.
+    member document.GetSolutionDocumentsWithFilePath(filePath: string) =
+        let filePath = Path.GetFullPathSafe filePath
+
+        document.TryFindInSolutions(fun solution ->
+            match solution.GetDocumentIdsWithFilePath filePath with
+            | ids when ids.IsEmpty -> ValueNone
+            | ids -> ValueSome [ for id in ids -> solution.GetDocument id ])
+        |> ValueOption.defaultValue []
+
+    member document.TryGetSolutionDocumentFromPath(filePath: string) =
+        document.GetSolutionDocumentsWithFilePath filePath |> Seq.tryHeadV
+
+    /// The document for the range's file, preferring this document's project or one it depends on.
+    member document.TryGetSolutionDocumentFromFSharpRange(range: range) =
+        document.TryFindInSolutions(fun solution ->
+            solution.TryGetDocumentFromFSharpRange(range, document.Project.Id)
+            |> ValueOption.ofOption)

vsintegration/src/FSharp.Editor/LanguageService/SymbolHelpers.fs

@@ -124,7 +124,7 @@ module internal SymbolHelpers =
                 let otherFile = getOtherFile currentDocument.FilePath
 
                 let! otherFileCheckResults =
-                    match currentDocument.Project.Solution.TryGetDocumentFromPath otherFile with
+                    match currentDocument.TryGetSolutionDocumentFromPath otherFile with
                     | ValueSome doc ->
                         cancellableTask {
                             let! _, checkFileResults = doc.GetFSharpParseAndCheckResultsAsync("findReferencedSymbolsAsync")

vsintegration/src/FSharp.Editor/LanguageService/Symbols.fs

@@ -64,11 +64,9 @@ type FSharpSymbolUse with
                     Some(SymbolScope.Projects([ currentDocument.Project ], isSymbolLocalForProject))
                 else
                     let projects =
-                        currentDocument.Project.Solution.GetDocumentIdsWithFilePath(filePath)
-                        |> Seq.map (fun x -> x.ProjectId)
-                        |> Seq.distinct
-                        |> Seq.map currentDocument.Project.Solution.GetProject
-                        |> Seq.toList
+                        currentDocument.GetSolutionDocumentsWithFilePath filePath
+                        |> List.map _.Project
+                        |> List.distinctBy _.Id
 
                     match projects with
                     | [] -> None

vsintegration/src/FSharp.Editor/Navigation/FindUsagesService.fs

@@ -59,18 +59,15 @@ module FSharpFindUsagesService =
         }
 
     // File can be included in more than one project, hence single `range` may results with multiple `Document`s.
-    let rangeToDocumentSpans (solution: Solution, range: range, symbolName: string) =
+    let rangeToDocumentSpans (document: Document, range: range, symbolName: string) =
         if range.Start = range.End then
             CancellableTask.singleton [||]
         else
             cancellableTask {
-                let documentIds = solution.GetDocumentIdsWithFilePath(range.FileName)
-
                 let! spans =
                     seq {
-                        for documentId in documentIds do
+                        for doc in document.GetSolutionDocumentsWithFilePath range.FileName do
                             cancellableTask {
-                                let doc = solution.GetDocument(documentId)
                                 let! cancellationToken = CancellableTask.getCancellationToken ()
                                 let! sourceText = doc.GetTextAsync(cancellationToken)
 
@@ -119,7 +116,7 @@ module FSharpFindUsagesService =
 
                     let! declarationSpans =
                         match declarationRange with
-                        | Some range -> rangeToDocumentSpans (document.Project.Solution, range, symbol.Ident.idText)
+                        | Some range -> rangeToDocumentSpans (document, range, symbol.Ident.idText)
                         | None -> CancellableTask.singleton [||]
 
                     let declarationSpans =