Detect inner loop

Author: bep

tpl/templates/decorator_integration_test.go

@@ -117,7 +117,6 @@ Home.
 	b.AssertFileContent("public/index.html", "<a><b><c>warning</c></b></b>")
 }
 
-// TODO1 detect inner usage inside with partial. That' a bite in the tail.
 func TestDecoratorNested2(t *testing.T) {
 	t.Parallel()
 
@@ -296,3 +295,24 @@ Sum: {{ with partial "add.html" $v }}
 	// 1 + 2 + 4 + 6 = 13
 	b.AssertFileContent("public/index.html", "Sum: 13$")
 }
+
+func TestDecoratorFailOnInnerInWith(t *testing.T) {
+	t.Parallel()
+
+	filesTemplate := `
+-- hugo.toml --
+-- layouts/_partials/b.html --
+<b>{{ inner . }}</b>
+-- layouts/home.html --
+{{ with partial "b.html" "hello" }}
+This construct creates a loop: {{PLACEHOLDER . }} 
+{{ end }}$
+`
+	for _, placeholder := range []string{"inner", "templates.Inner", "  inner", "\ninner"} {
+		files := strings.ReplaceAll(filesTemplate, "PLACEHOLDER", placeholder)
+		b, err := hugolib.TestE(t, files)
+
+		b.Assert(err, qt.Not(qt.IsNil))
+		b.Assert(err.Error(), qt.Contains, "inner cannot be used inside a with block that wraps a partial decorator")
+	}
+}

tpl/tplimpl/templates.go

@@ -53,16 +53,16 @@ func (s *TemplateStore) parseTemplate(ti *TemplInfo, replace bool) error {
 	return err
 }
 
-func (t *templateNamespace) newBlankTemplate(ti *TemplInfo, name string) tpl.Template {
+func (t *templateNamespace) newBlankTemplate(ti *TemplInfo) tpl.Template {
 	if ti.D.IsPlainText {
-		tt, err := t.parseText.New(name).Parse("")
+		tt, err := t.parseText.New(ti.Name()).Parse("")
 		if err != nil {
 			panic(err)
 		}
 		return tt
 
 	}
-	tt, err := t.parseHTML.New(name).Parse("")
+	tt, err := t.parseHTML.New(ti.Name()).Parse("")
 	if err != nil {
 		panic(err)
 	}

tpl/tplimpl/templatestore.go

@@ -1581,7 +1581,7 @@ func (s *TemplateStore) createTemplatesSnapshot() error {
 	return nil
 }
 
-func (s *TemplateStore) addTransformedTemplateRootStep1(name string, subCategory SubCategory) (*TemplInfo, error) {
+func (s *TemplateStore) addTransformedTemplateInsert(name string, subCategory SubCategory) (*TemplInfo, error) {
 	pi := s.opts.PathParser.Parse(files.ComponentFolderLayouts, name)
 	ti, err := s.insertTemplate(pi, nil, subCategory, true, s.treeMain)
 	if err != nil {
@@ -1590,8 +1590,8 @@ func (s *TemplateStore) addTransformedTemplateRootStep1(name string, subCategory
 	return ti, nil
 }
 
-func (s *TemplateStore) addTransformedTemplateRoot(owner, this *TemplInfo, name string, subCategory SubCategory, root *parse.ListNode) (*parse.Tree, error) {
-	templ := s.tns.newBlankTemplate(owner, name)
+func (s *TemplateStore) addTransformedTemplateSetTree(this *TemplInfo, root *parse.ListNode) (*parse.Tree, error) {
+	templ := s.tns.newBlankTemplate(this)
 	tree := getParseTree(templ)
 	tree.Root = root
 	this.Template = templ

tpl/tplimpl/templatetransform.go

@@ -3,6 +3,7 @@ package tplimpl
 import (
 	"errors"
 	"fmt"
+	"regexp"
 	"slices"
 	"strings"
 
@@ -84,7 +85,7 @@ func applyTemplateTransformers(
 	}
 
 	if err := c.applyTransformationsAndSetReturnWrapper(tree); err != nil {
-		return c, fmt.Errorf("failed to transform template %q: %w", t.Name, err)
+		return c, fmt.Errorf("failed to transform template %q: %w", t.Name(), err)
 	}
 
 	return c, c.err
@@ -263,19 +264,25 @@ func (c *templateTransformContext) isWithDefer(idArg parse.Node) bool {
 // PartialDecoratorPrefix is the prefix for internal partial decorator templates.
 const PartialDecoratorPrefix = "_internal/decorator_"
 
+var templatesInnerRe = regexp.MustCompile(`{{\s*(templates\.Inner\b|inner\b)`)
+
 func (c *templateTransformContext) handleWithPartial(withNode *parse.WithNode) {
-	innerHash := hashing.XxHashFromStringHexEncoded(withNode.List.String())
+	withNodeInnerString := withNode.List.String()
+	if templatesInnerRe.MatchString(withNodeInnerString) {
+		c.err = fmt.Errorf("inner cannot be used inside a with block that wraps a partial decorator")
+		return
+	}
+	innerHash := hashing.XxHashFromStringHexEncoded(withNodeInnerString)
 	internalPartialName := fmt.Sprintf("_partials/%s%s", PartialDecoratorPrefix, innerHash)
 
 	if c.lookupFn(internalPartialName, c.t) == nil {
 		innerCopy := withNode.List.CopyList()
-		// TODO1 rework to support return.
-		ti, err := c.store.addTransformedTemplateRootStep1(internalPartialName, SubCategoryInline)
+		ti, err := c.store.addTransformedTemplateInsert(internalPartialName, SubCategoryInline)
 		cc := newTemplateTransformContext(ti, c.store, c.lookupFn)
 		if err != nil {
 			c.err = fmt.Errorf("failed to create internal partial decorator template %q: %w", internalPartialName, err)
 		}
-		tree, err := c.store.addTransformedTemplateRoot(c.t, ti, internalPartialName, SubCategoryInline, innerCopy)
+		tree, err := c.store.addTransformedTemplateSetTree(ti, innerCopy)
 		if err != nil {
 			c.err = fmt.Errorf("failed to add internal partial decorator template %q: %w", internalPartialName, err)
 			return