From 3d28e5740216fd3340098880b50c755f3a1b63ed Mon Sep 17 00:00:00 2001
From: youdie006 <xncb135@korea.ac.kr>
Date: Mon, 7 Sep 2026 11:39:37 +0900
Subject: [PATCH] Select asset templates by the final extension only

compileTemplatesFromDir takes filepath.Ext(rel), with a comment naming
the case it fixes: a directory called users.tmpl whose files are still
normal templates. compileTemplatesFromAsset never got that fix and
still joins everything after the first dot, so for
users.tmpl/index.tmpl it computes .tmpl/index.tmpl.

No configured extension contains a path separator, so the match below
is vacuously false and the template is silently skipped. The same
happens for any multi-dot name such as a.b.tmpl.

Use filepath.Ext here too, so both loaders select the same files and
produce the same template names.
---
 render.go                             |  2 +-
 render_html_test.go                   | 30 +++++++++++++++++++++++++++
 testdata/dotdir/a.b.tmpl              |  1 +
 testdata/dotdir/users.tmpl/index.tmpl |  1 +
 4 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 testdata/dotdir/a.b.tmpl
 create mode 100644 testdata/dotdir/users.tmpl/index.tmpl

diff --git a/render.go b/render.go
index 3bf5d36..ec9dbb7 100644
--- a/render.go
+++ b/render.go
@@ -360,7 +360,7 @@ func (r *Render) compileTemplatesFromAsset() {
 
 		ext := ""
 		if strings.Contains(rel, ".") {
-			ext = "." + strings.Join(strings.Split(rel, ".")[1:], ".")
+			ext = filepath.Ext(rel) // match the directory walker: only the final extension
 		}
 
 		for _, extension := range r.opt.Extensions {
diff --git a/render_html_test.go b/render_html_test.go
index 4ce17f0..08e167e 100644
--- a/render_html_test.go
+++ b/render_html_test.go
@@ -524,3 +524,33 @@ func TestHTMLPerCallContentType(t *testing.T) {
 	expect(t, res.Header().Get(ContentType), "application/xhtml+xml")
 	expect(t, res.Body.String(), "<h1>Hello gophers</h1>\n")
 }
+
+var dotDirFiles = map[string]string{
+	"testdata/dotdir/users.tmpl/index.tmpl": "Hello asset",
+	"testdata/dotdir/a.b.tmpl":              "Hello ab",
+}
+
+// The asset loader must select templates by the same extension rule as the
+// directory walker, including under a dot-named directory and for multi-dot names.
+func TestHTMLAssetExtensionMatchesDirectory(t *testing.T) {
+	names := make([]string, 0, len(dotDirFiles))
+	for n := range dotDirFiles {
+		names = append(names, n)
+	}
+
+	dirRender := New(Options{Directory: "testdata/dotdir"})
+	assetRender := New(Options{
+		Directory:  "testdata/dotdir",
+		Asset:      func(n string) ([]byte, error) { return []byte(dotDirFiles[n]), nil },
+		AssetNames: func() []string { return names },
+	})
+
+	for _, name := range []string{"users.tmpl/index", "a.b"} {
+		if dirRender.TemplateLookup(name) == nil {
+			t.Errorf("directory mode did not load %q", name)
+		}
+		if assetRender.TemplateLookup(name) == nil {
+			t.Errorf("asset mode did not load %q", name)
+		}
+	}
+}
diff --git a/testdata/dotdir/a.b.tmpl b/testdata/dotdir/a.b.tmpl
new file mode 100644
index 0000000..7fcc02d
--- /dev/null
+++ b/testdata/dotdir/a.b.tmpl
@@ -0,0 +1 @@
+Hello ab
\ No newline at end of file
diff --git a/testdata/dotdir/users.tmpl/index.tmpl b/testdata/dotdir/users.tmpl/index.tmpl
new file mode 100644
index 0000000..4d0ae53
--- /dev/null
+++ b/testdata/dotdir/users.tmpl/index.tmpl
@@ -0,0 +1 @@
+Hello asset
\ No newline at end of file