From 4455b656106759376bacd5e71ee3b264dbe1527d Mon Sep 17 00:00:00 2001
From: Yegappan Lakshmanan <yegappan@yahoo.com>
Date: Tue, 8 Mar 2022 14:22:09 -0800
Subject: [PATCH] Update the switch source header support

---
 autoload/lsp/handlers.vim  | 4 ++++
 autoload/lsp/lsp.vim       | 1 +
 autoload/lsp/lspserver.vim | 1 +
 doc/lsp.txt                | 4 +++-
 plugin/lsp.vim             | 9 +++++++++
 5 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/autoload/lsp/handlers.vim b/autoload/lsp/handlers.vim
index b6fe263..89b8ddf 100644
--- a/autoload/lsp/handlers.vim
+++ b/autoload/lsp/handlers.vim
@@ -147,8 +147,12 @@ def ProcessDefDeclReply(lspserver: dict<any>, req: dict<any>, reply: dict<any>):
 enddef
 
 # process the 'textDocument/switchSourceHeader' reply from the LSP server
+# Clangd specific extension
 # Result: URI | null
 def ProcessSwitchHeaderReply(lspserver: dict<any>, req: dict<any>, reply: dict<any>): void
+  if reply.result->empty()
+    return
+  endif
   var fname = util.LspUriToFile(reply.result)
   if (&modified && !&hidden) || &buftype != ''
     # if the current buffer has unsaved changes and 'hidden' is not set,
diff --git a/autoload/lsp/lsp.vim b/autoload/lsp/lsp.vim
index 19abc90..e4f4c8b 100644
--- a/autoload/lsp/lsp.vim
+++ b/autoload/lsp/lsp.vim
@@ -216,6 +216,7 @@ export def GotoDefinition(peek: bool)
 enddef
 
 # Switch source header using "textDocument/switchSourceHeader" LSP request
+# (Clangd specifc extension)
 export def SwitchSourceHeader()
   var lspserver: dict<any> = CurbufGetServerChecked()
   if lspserver->empty()
diff --git a/autoload/lsp/lspserver.vim b/autoload/lsp/lspserver.vim
index e99d941..92ab3b1 100644
--- a/autoload/lsp/lspserver.vim
+++ b/autoload/lsp/lspserver.vim
@@ -479,6 +479,7 @@ enddef
 
 # Request: "textDocument/switchSourceHeader"
 # Param: TextDocumentIdentifier
+# Clangd specific extension
 def SwitchSourceHeader(lspserver: dict<any>)
   var req = lspserver.createRequest('textDocument/switchSourceHeader')
   req.params->extend({uri: util.LspFileToUri(@%)})
diff --git a/doc/lsp.txt b/doc/lsp.txt
index 7f631ce..0ad70a0 100644
--- a/doc/lsp.txt
+++ b/doc/lsp.txt
@@ -319,7 +319,9 @@ diagnostic messages, you can add the following line to your .vimrc file:
 			Default is false.
 
 						*:LspSwitchSourceHeader*
-:LspSwitchSourceHeader	Switch between source and header files.
+:LspSwitchSourceHeader	Switch between source and header files. This is a
+			Clangd specific extension and only works with C/C++
+			source files.
 
 						*:LspDiagShow*
 :LspDiagShow		Creates a new location list with the diagnostics
diff --git a/plugin/lsp.vim b/plugin/lsp.vim
index d305778..dd3f79e 100644
--- a/plugin/lsp.vim
+++ b/plugin/lsp.vim
@@ -6,6 +6,10 @@ if !has('patch-8.2.2342')
   finish
 endif
 
+# The following is needed to support both Vim 8.2.3741 (shipped with Ubuntu
+# 21.10) and the latest Vim. The Vim9 script syntax for import changed between
+# these two versions. Once offical Vim9 is out, the following can be
+# simplified.
 var opt = {}
 var lspf = {}
 if has('patch-8.2.4257')
@@ -85,6 +89,7 @@ elseif has('patch-8.2.4019')
   lspf.hover = lsp_import.Hover
   lspf.selectionExpand = lsp_import.SelectionExpand
   lspf.selectionShrink = lsp_import.SelectionShrink
+  lspf.switchSourceHeader = lsp_import.SwitchSourceHeader
   lspf.foldDocument = lsp_import.FoldDocument
   lspf.listWorkspaceFolders = lsp_import.ListWorkspaceFolders
   lspf.addWorkspaceFolder = lsp_import.AddWorkspaceFolder
@@ -121,6 +126,7 @@ else
 	  Hover,
 	  SelectionExpand,
 	  SelectionShrink,
+	  SwitchSourceHeader,
 	  FoldDocument,
 	  ListWorkspaceFolders,
 	  AddWorkspaceFolder,
@@ -163,6 +169,7 @@ else
   lspf.hover = Hover
   lspf.selectionExpand = SelectionExpand
   lspf.selectionShrink = SelectionShrink
+  lspf.switchSourceHeader = SwitchSourceHeader
   lspf.foldDocument = FoldDocument
   lspf.listWorkspaceFolders = ListWorkspaceFolders
   lspf.addWorkspaceFolder = AddWorkspaceFolder
@@ -256,6 +263,8 @@ command! -nargs=0 -bar LspDiagHighlightEnable call TdiagHighlightEnable()
 command! -nargs=0 -bar LspDiagHighlightDisable call TdiagHighlightDisable()
 command! -nargs=0 -bar LspShowReferences call TshowReferences(v:false)
 command! -nargs=0 -bar LspPeekReferences call TshowReferences(v:true)
+# Clangd specifc extension to switch from one C/C++ source file to a
+# corresponding header file
 command! -nargs=0 -bar LspSwitchSourceHeader call TswitchSourceHeader()
 command! -nargs=0 -bar LspHighlight call LspDocHighlight()
 command! -nargs=0 -bar LspHighlightClear call LspDocHighlightClear()
-- 
2.48.1