From 8c2afedbc46e78b502aa0eedd5c05e6b227d586b Mon Sep 17 00:00:00 2001
From: Yegappan Lakshmanan <yegappan@yahoo.com>
Date: Sun, 27 Nov 2022 13:36:40 -0800
Subject: [PATCH] When starting to edit a file, update the inlay hints

---
 autoload/lsp/inlayhints.vim | 28 ++++++++++++++++++++++------
 autoload/lsp/lspserver.vim  |  6 ++++++
 doc/lsp.txt                 |  3 ++-
 3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/autoload/lsp/inlayhints.vim b/autoload/lsp/inlayhints.vim
index 86350bb..864ecb0 100644
--- a/autoload/lsp/inlayhints.vim
+++ b/autoload/lsp/inlayhints.vim
@@ -66,7 +66,7 @@ def InlayHintsCallback(lspserver: dict<any>, timerid: number)
 enddef
 
 # Update all the inlay hints.  A timer is used to throttle the updates.
-def InlayHintsUpdate()
+def LspInlayHintsUpdate()
   if !get(b:, 'LspInlayHintsNeedsUpdate', true)
     return
   endif
@@ -87,12 +87,18 @@ def InlayHintsUpdate()
 enddef
 
 # Text is modified. Need to update the inlay hints.
-def InlayHintsChanged()
+def LspInlayHintsChanged()
   b:LspInlayHintsNeedsUpdate = true
 enddef
 
+# Trigger an update of the inlay hints in the current buffer.
+export def LspInlayHintsUpdateNow()
+  b:LspInlayHintsNeedsUpdate = true
+  LspInlayHintsUpdate()
+enddef
+
 # Stop updating the inlay hints.
-def InlayHintsUpdateStop()
+def LspInlayHintsUpdateStop()
   var timerid = get(b:, 'LspInlayHintsTimer', -1)
   if timerid != -1
     timerid->timer_stop()
@@ -104,18 +110,28 @@ enddef
 export def BufferInit(bnr: number)
   var acmds: list<dict<any>> = []
 
+  # Update the inlay hints (if needed) when the cursor is not moved for some
+  # time.
   acmds->add({bufnr: bnr,
 		event: ['CursorHold'],
 		group: 'LSPBufferAutocmds',
-		cmd: 'InlayHintsUpdate()'})
+		cmd: 'LspInlayHintsUpdate()'})
+  # After the text in the current buffer is modified, the inlay hints need to
+  # be updated.
   acmds->add({bufnr: bnr,
 		event: ['TextChanged'],
 		group: 'LSPBufferAutocmds',
-		cmd: 'InlayHintsChanged()'})
+		cmd: 'LspInlayHintsChanged()'})
+  # Editing a file should trigger an inlay hint update.
+  acmds->add({bufnr: bnr,
+		event: ['BufReadPost'],
+		group: 'LSPBufferAutocmds',
+		cmd: 'LspInlayHintsUpdateNow()'})
+  # Inlay hints need not be updated if a buffer is no longer active.
   acmds->add({bufnr: bnr,
 		event: ['BufLeave'],
 		group: 'LSPBufferAutocmds',
-		cmd: 'InlayHintsUpdateStop()'})
+		cmd: 'LspInlayHintsUpdateStop()'})
 
   autocmd_add(acmds)
 enddef
diff --git a/autoload/lsp/lspserver.vim b/autoload/lsp/lspserver.vim
index 4a9148c..15d29ec 100644
--- a/autoload/lsp/lspserver.vim
+++ b/autoload/lsp/lspserver.vim
@@ -367,6 +367,12 @@ def ServerInitReply(lspserver: dict<any>, initResult: dict<any>): void
   if bufwinid('LSP-Outline') != -1
     lspserver.getDocSymbols(@%)
   endif
+
+  # Update the inlay hints (if enabled)
+  if opt.lspOptions.showInlayHints && (lspserver.isInlayHintProvider
+				    || lspserver.isClangdInlayHintsProvider)
+    inlayhints.LspInlayHintsUpdateNow()
+  endif
 enddef
 
 # Request: 'initialize'
diff --git a/doc/lsp.txt b/doc/lsp.txt
index a17f785..bc3d47b 100644
--- a/doc/lsp.txt
+++ b/doc/lsp.txt
@@ -292,7 +292,8 @@ showDiagOnStatusLine	Show a diagnostic message on a status line.
 			By default this is set to false.
 showInlayHints		Show inlay hints from the language server.  By default
 			this is set to false.  The inlay hint text is
-			displayed as a virtual text.
+			displayed as a virtual text.  Needs Vim version
+			9.0.0178 or later.
 showSignature		In insert mode, automatically show the current symbol
 			signature in a popup. By default this is set to true.
 snippetSupport		Enable snippet completion support.  Need a snippet
-- 
2.48.1