tpl/templates: Fix templates.Exist issue with base templates

Fixes #9477

tpl/templates/integration_test.go

@@ -0,0 +1,85 @@
+// Copyright 2022 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package templates_test
+
+import (
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestExists(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+baseURL = 'http://example.com/'
+-- layouts/index.html --
+index.html: {{ templates.Exists "index.html" }}
+post/single.html: {{ templates.Exists "post/single.html" }}
+partials/foo.html: {{ templates.Exists "partials/foo.html" }}
+partials/doesnotexist.html: {{ templates.Exists "partials/doesnotexist.html" }}
+-- layouts/post/single.html --
+-- layouts/partials/foo.html --
+  `
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+		},
+	).Build()
+
+	b.AssertFileContent("public/index.html", `
+index.html: true
+post/single.html: true
+partials/foo.html: true
+partials/doesnotexist.html: false  
+`)
+}
+
+func TestExistsWithBaseOf(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+baseURL = 'http://example.com/'
+-- layouts/baseof.html --
+{{ block "main" . }}{{ end }}
+-- layouts/index.html --
+{{ define "main" }}
+index.html: {{ templates.Exists "index.html" }}
+post/single.html: {{ templates.Exists "post/single.html" }}
+post/doesnotexist.html: {{ templates.Exists "post/doesnotexist.html" }}
+{{ end }}
+-- layouts/post/single.html --
+{{ define "main" }}MAIN{{ end }}
+
+
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+		},
+	).Build()
+
+	b.AssertFileContent("public/index.html", `
+index.html: true
+post/single.html: true
+post/doesnotexist.html: false
+
+`)
+}

tpl/templates/templates.go

@@ -34,6 +34,5 @@ type Namespace struct {
 // Note that this is the Unix-styled relative path including filename suffix,
 // e.g. partials/header.html
 func (ns *Namespace) Exists(name string) bool {
-	_, found := ns.deps.Tmpl().Lookup(name)
-	return found
+	return ns.deps.Tmpl().HasTemplate(name)
 }