Reimplement and simplify Hugo's template system

See #13541 for details.

Fixes #13545
Fixes #13515
Closes #7964
Closes #13365
Closes #12988
Closes #4891

tpl/tplimpl/template_funcs.go

@@ -1,4 +1,4 @@
-// Copyright 2017-present The Hugo Authors. All rights reserved.
+// Copyright 2025 The Hugo Authors. All rights reserved.
 //
 // Portions Copyright The Go Authors.
 
@@ -25,46 +25,7 @@ import (
 	"github.com/gohugoio/hugo/identity"
 	"github.com/gohugoio/hugo/tpl"
 
-	template "github.com/gohugoio/hugo/tpl/internal/go_templates/htmltemplate"
 	texttemplate "github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate"
-
-	"github.com/gohugoio/hugo/deps"
-
-	"github.com/gohugoio/hugo/tpl/internal"
-
-	// Init the namespaces
-	_ "github.com/gohugoio/hugo/tpl/cast"
-	_ "github.com/gohugoio/hugo/tpl/collections"
-	_ "github.com/gohugoio/hugo/tpl/compare"
-	_ "github.com/gohugoio/hugo/tpl/crypto"
-	_ "github.com/gohugoio/hugo/tpl/css"
-	_ "github.com/gohugoio/hugo/tpl/data"
-	_ "github.com/gohugoio/hugo/tpl/debug"
-	_ "github.com/gohugoio/hugo/tpl/diagrams"
-	_ "github.com/gohugoio/hugo/tpl/encoding"
-	_ "github.com/gohugoio/hugo/tpl/fmt"
-	_ "github.com/gohugoio/hugo/tpl/hash"
-	_ "github.com/gohugoio/hugo/tpl/hugo"
-	_ "github.com/gohugoio/hugo/tpl/images"
-	_ "github.com/gohugoio/hugo/tpl/inflect"
-	_ "github.com/gohugoio/hugo/tpl/js"
-	_ "github.com/gohugoio/hugo/tpl/lang"
-	_ "github.com/gohugoio/hugo/tpl/math"
-	_ "github.com/gohugoio/hugo/tpl/openapi/openapi3"
-	_ "github.com/gohugoio/hugo/tpl/os"
-	_ "github.com/gohugoio/hugo/tpl/page"
-	_ "github.com/gohugoio/hugo/tpl/partials"
-	_ "github.com/gohugoio/hugo/tpl/path"
-	_ "github.com/gohugoio/hugo/tpl/reflect"
-	_ "github.com/gohugoio/hugo/tpl/resources"
-	_ "github.com/gohugoio/hugo/tpl/safe"
-	_ "github.com/gohugoio/hugo/tpl/site"
-	_ "github.com/gohugoio/hugo/tpl/strings"
-	_ "github.com/gohugoio/hugo/tpl/templates"
-	_ "github.com/gohugoio/hugo/tpl/time"
-	_ "github.com/gohugoio/hugo/tpl/transform"
-	_ "github.com/gohugoio/hugo/tpl/urls"
-	maps0 "maps"
 )
 
 var (
@@ -212,89 +173,3 @@ func (t *templateExecHelper) trackDependencies(ctx context.Context, tmpl texttem
 
 	return ctx
 }
-
-func newTemplateExecuter(d *deps.Deps) (texttemplate.Executer, map[string]reflect.Value) {
-	funcs := createFuncMap(d)
-	funcsv := make(map[string]reflect.Value)
-
-	for k, v := range funcs {
-		vv := reflect.ValueOf(v)
-		funcsv[k] = vv
-	}
-
-	// Duplicate Go's internal funcs here for faster lookups.
-	for k, v := range template.GoFuncs {
-		if _, exists := funcsv[k]; !exists {
-			vv, ok := v.(reflect.Value)
-			if !ok {
-				vv = reflect.ValueOf(v)
-			}
-			funcsv[k] = vv
-		}
-	}
-
-	for k, v := range texttemplate.GoFuncs {
-		if _, exists := funcsv[k]; !exists {
-			funcsv[k] = v
-		}
-	}
-
-	exeHelper := &templateExecHelper{
-		watching:   d.Conf.Watching(),
-		funcs:      funcsv,
-		site:       reflect.ValueOf(d.Site),
-		siteParams: reflect.ValueOf(d.Site.Params()),
-	}
-
-	return texttemplate.NewExecuter(
-		exeHelper,
-	), funcsv
-}
-
-func createFuncMap(d *deps.Deps) map[string]any {
-	if d.TmplFuncMap != nil {
-		return d.TmplFuncMap
-	}
-	funcMap := template.FuncMap{}
-
-	nsMap := make(map[string]any)
-	var onCreated []func(namespaces map[string]any)
-
-	// Merge the namespace funcs
-	for _, nsf := range internal.TemplateFuncsNamespaceRegistry {
-		ns := nsf(d)
-		if _, exists := funcMap[ns.Name]; exists {
-			panic(ns.Name + " is a duplicate template func")
-		}
-		funcMap[ns.Name] = ns.Context
-		contextV, err := ns.Context(context.Background())
-		if err != nil {
-			panic(err)
-		}
-		nsMap[ns.Name] = contextV
-		for _, mm := range ns.MethodMappings {
-			for _, alias := range mm.Aliases {
-				if _, exists := funcMap[alias]; exists {
-					panic(alias + " is a duplicate template func")
-				}
-				funcMap[alias] = mm.Method
-			}
-		}
-
-		if ns.OnCreated != nil {
-			onCreated = append(onCreated, ns.OnCreated)
-		}
-	}
-
-	for _, f := range onCreated {
-		f(nsMap)
-	}
-
-	if d.OverloadedTemplateFuncs != nil {
-		maps0.Copy(funcMap, d.OverloadedTemplateFuncs)
-	}
-
-	d.TmplFuncMap = funcMap
-
-	return d.TmplFuncMap
-}