From 4911b5da93e52b1fb28ab8328135ac3fa0a6c9a0 Mon Sep 17 00:00:00 2001
From: Adrian Hesketh <adrianhesketh@hushmail.com>
Date: Tue, 12 Dec 2023 21:14:56 +0000
Subject: [PATCH] fix: diagnostics set to nil, which causes issues in some LSP
 clients (and is against spec)

---
 .version                                  |  2 +-
 cmd/templ/lspcmd/proxy/diagnosticcache.go | 22 +++++++++++++++++++++-
 cmd/templ/lspcmd/proxy/server.go          |  6 ++++--
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/.version b/.version
index 894b1133a..9993225f7 100644
--- a/.version
+++ b/.version
@@ -1 +1 @@
-0.2.480
\ No newline at end of file
+0.2.485
\ No newline at end of file
diff --git a/cmd/templ/lspcmd/proxy/diagnosticcache.go b/cmd/templ/lspcmd/proxy/diagnosticcache.go
index 3a33979c9..00ec5c21d 100644
--- a/cmd/templ/lspcmd/proxy/diagnosticcache.go
+++ b/cmd/templ/lspcmd/proxy/diagnosticcache.go
@@ -1,8 +1,9 @@
 package proxy
 
 import (
-	lsp "github.com/a-h/protocol"
 	"sync"
+
+	lsp "github.com/a-h/protocol"
 )
 
 func NewDiagnosticCache() *DiagnosticCache {
@@ -22,20 +23,39 @@ type DiagnosticCache struct {
 	cache map[string]fileDiagnostic
 }
 
+func zeroLengthSliceIfNil(diags []lsp.Diagnostic) []lsp.Diagnostic {
+	if diags == nil {
+		return make([]lsp.Diagnostic, 0)
+	}
+	return diags
+}
+
 func (dc *DiagnosticCache) AddTemplDiagnostics(uri string, goDiagnostics []lsp.Diagnostic) []lsp.Diagnostic {
+	goDiagnostics = zeroLengthSliceIfNil(goDiagnostics)
 	dc.m.Lock()
 	defer dc.m.Unlock()
 	diag := dc.cache[uri]
 	diag.goplsDiagnostics = goDiagnostics
+	diag.templDiagnostics = zeroLengthSliceIfNil(diag.templDiagnostics)
 	dc.cache[uri] = diag
 	return append(diag.templDiagnostics, goDiagnostics...)
 }
 
+func (dc *DiagnosticCache) ClearTemplDiagnostics(uri string) {
+	dc.m.Lock()
+	defer dc.m.Unlock()
+	diag := dc.cache[uri]
+	diag.templDiagnostics = make([]lsp.Diagnostic, 0)
+	dc.cache[uri] = diag
+}
+
 func (dc *DiagnosticCache) AddGoDiagnostics(uri string, templDiagnostics []lsp.Diagnostic) []lsp.Diagnostic {
+	templDiagnostics = zeroLengthSliceIfNil(templDiagnostics)
 	dc.m.Lock()
 	defer dc.m.Unlock()
 	diag := dc.cache[uri]
 	diag.templDiagnostics = templDiagnostics
+	diag.goplsDiagnostics = zeroLengthSliceIfNil(diag.goplsDiagnostics)
 	dc.cache[uri] = diag
 	return append(diag.goplsDiagnostics, templDiagnostics...)
 }
diff --git a/cmd/templ/lspcmd/proxy/server.go b/cmd/templ/lspcmd/proxy/server.go
index 978fe0c75..524ab8acd 100644
--- a/cmd/templ/lspcmd/proxy/server.go
+++ b/cmd/templ/lspcmd/proxy/server.go
@@ -182,9 +182,11 @@ func (p *Server) parseTemplate(ctx context.Context, uri uri.URI, templateText st
 		return
 	}
 	// Clear templ diagnostics.
+	p.DiagnosticCache.ClearTemplDiagnostics(string(uri))
 	err = p.Client.PublishDiagnostics(ctx, &lsp.PublishDiagnosticsParams{
-		URI:         uri,
-		Diagnostics: p.DiagnosticCache.AddGoDiagnostics(string(uri), nil),
+		URI: uri,
+		// Cannot be nil as per https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#publishDiagnosticsParams
+		Diagnostics: []lsp.Diagnostic{},
 	})
 	if err != nil {
 		p.Log.Error("failed to publish diagnostics", zap.Error(err))