From 098a7b8976266898bbf0b899f01bb0863b272cf3 Mon Sep 17 00:00:00 2001
From: Artem Pyanykh <artem.pyanykh@gmail.com>
Date: Thu, 8 Sep 2022 22:24:25 +0100
Subject: [PATCH] diag: Do not emit cross-file diag for single-file folders

---
 Marksman/Diag.fs       | 11 ++++++++++-
 Marksman/Workspace.fs  |  5 +++++
 Marksman/Workspace.fsi |  1 +
 Tests/DiagTest.fs      | 17 +++++++++++++++++
 4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/Marksman/Diag.fs b/Marksman/Diag.fs
index 4511c38..71568b7 100644
--- a/Marksman/Diag.fs
+++ b/Marksman/Diag.fs
@@ -42,6 +42,13 @@ let checkNonBreakingWhitespace (doc: Doc) =
 
             [ NonBreakableWhitespace(whitespaceRange) ])
 
+let isCrossFileLink uref =
+    match uref with
+    | Uref.Doc _ -> true
+    | Uref.Heading(doc = Some _) -> true
+    | Uref.Heading(doc = None) -> false
+    | Uref.LinkDef _ -> false
+
 let checkLink (folder: Folder) (doc: Doc) (link: Element) : seq<Entry> =
     let uref = Uref.ofElement link
 
@@ -50,7 +57,9 @@ let checkLink (folder: Folder) (doc: Doc) (link: Element) : seq<Entry> =
     | Some uref ->
         let refs = Dest.tryResolveUref uref doc folder |> Array.ofSeq
 
-        if refs.Length = 1 then
+        if Folder.isSingleFile folder && isCrossFileLink uref then
+            []
+        else if refs.Length = 1 then
             []
         else if refs.Length = 0 then
             match link with
diff --git a/Marksman/Workspace.fs b/Marksman/Workspace.fs
index a21e215..91c739f 100644
--- a/Marksman/Workspace.fs
+++ b/Marksman/Workspace.fs
@@ -149,6 +149,11 @@ module Folder =
 
     let singleFile doc = SingleFile doc
 
+    let isSingleFile =
+        function
+        | SingleFile _ -> true
+        | MultiFile _ -> false
+
     let multiFile name root docs = MultiFile(name, root, docs)
 
     let docs: Folder -> seq<Doc> =
diff --git a/Marksman/Workspace.fsi b/Marksman/Workspace.fsi
index ee18b4b..1236b5f 100644
--- a/Marksman/Workspace.fsi
+++ b/Marksman/Workspace.fsi
@@ -56,6 +56,7 @@ module Folder =
 
     val singleFile: Doc -> Folder
     val multiFile: name: string -> root: RootPath -> docs: Map<PathUri, Doc> -> Folder
+    val isSingleFile: Folder -> bool
 
     val withDoc: Doc -> Folder -> Folder
     val withoutDoc: PathUri -> Folder -> option<Folder>
diff --git a/Tests/DiagTest.fs b/Tests/DiagTest.fs
index a37bdcf..a1a9aa8 100644
--- a/Tests/DiagTest.fs
+++ b/Tests/DiagTest.fs
@@ -85,3 +85,20 @@ let noDiagOnNonMarkdownFiles () =
           "fake.md", "Link to non-existent document at 'another%20bad.md'" ],
         diag
     )
+
+[<Fact>]
+let noCrossFileDiagOnSingleFileFolders () =
+    let doc =
+        FakeDoc.Mk(
+            [| "[](bad.md)" //
+               "[[another-bad]]"
+               "[bad-ref][bad-ref]" |]
+        )
+
+    let folder = Folder.singleFile doc
+    let diag = checkFolder folder |> diagToHuman
+
+    Assert.Equal<string * string>(
+        [ "fake.md", "Link to non-existent link definition with the label 'bad-ref'" ],
+        diag
+    )