tpl: Get rid of the custom template truth logic

Fixes gohugoio#6615

hugolib/template_test.go

@@ -337,6 +337,34 @@ Partial cached3: {{ partialCached "p1" "input3" $key2 }}
 `)
 }
 
+// https://github.com/gohugoio/hugo/issues/6615
+func TestTemplateTruth(t *testing.T) {
+	b := newTestSitesBuilder(t)
+	b.WithTemplatesAdded("index.html", `
+{{ $p := index site.RegularPages 0 }}
+{{ $zero := $p.ExpiryDate }}
+{{ $notZero := time.Now }}
+
+if: Zero: {{ if $zero }}FAIL{{ else }}OK{{ end }}
+if: Not Zero: {{ if $notZero }}OK{{ else }}Fail{{ end }}
+not: Zero: {{ if not $zero }}OK{{ else }}FAIL{{ end }}
+not: Not Zero: {{ if not $notZero }}FAIL{{ else }}OK{{ end }}
+
+with: Zero {{ with $zero }}FAIL{{ else }}OK{{ end }}
+
+`)
+
+	b.Build(BuildCfg{})
+
+	b.AssertFileContent("public/index.html", `
+if: Zero: OK
+if: Not Zero: OK
+not: Zero: OK
+not: Not Zero: OK
+with: Zero OK
+`)
+}
+
 func TestTemplateDependencies(t *testing.T) {
 	b := newTestSitesBuilder(t).Running()
 

scripts/fork_go_templates/main.go

@@ -60,6 +60,7 @@ var (
 		"func (s *state) evalFunction", "func (s *state) evalFunctionOld",
 		"func (s *state) evalField(", "func (s *state) evalFieldOld(",
 		"func (s *state) evalCall(", "func (s *state) evalCallOld(",
+		"func isTrue(val reflect.Value) (truth, ok bool) {", "func isTrueOld(val reflect.Value) (truth, ok bool) {",
 	)
 
 	htmlTemplateReplacers = strings.NewReplacer(

tpl/compare/init.go

@@ -71,27 +71,6 @@ func init() {
 			[][2]string{},
 		)
 
-		ns.AddMethodMapping(ctx.And,
-			[]string{"and"},
-			[][2]string{},
-		)
-
-		ns.AddMethodMapping(ctx.Or,
-			[]string{"or"},
-			[][2]string{},
-		)
-
-		// getif is used internally by Hugo. Do not document.
-		ns.AddMethodMapping(ctx.getIf,
-			[]string{"getif"},
-			[][2]string{},
-		)
-
-		ns.AddMethodMapping(ctx.Not,
-			[]string{"not"},
-			[][2]string{},
-		)
-
 		ns.AddMethodMapping(ctx.Conditional,
 			[]string{"cond"},
 			[][2]string{

tpl/internal/go_templates/texttemplate/exec.go

@@ -307,7 +307,7 @@ func IsTrue(val interface{}) (truth, ok bool) {
 	return isTrue(reflect.ValueOf(val))
 }
 
-func isTrue(val reflect.Value) (truth, ok bool) {
+func isTrueOld(val reflect.Value) (truth, ok bool) {
 	if !val.IsValid() {
 		// Something like var x interface{}, never set. It's a form of nil.
 		return false, true

tpl/internal/go_templates/texttemplate/hugo_template.go

@@ -17,6 +17,8 @@ import (
 	"io"
 	"reflect"
 
+	"github.com/gohugoio/hugo/common/hreflect"
+
 	"github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate/parse"
 )
 
@@ -301,3 +303,7 @@ func (s *state) evalCall(dot, fun reflect.Value, node parse.Node, name string, a
 	}
 	return v
 }
+
+func isTrue(val reflect.Value) (truth, ok bool) {
+	return hreflect.IsTruthfulValue(val), true
+}

tpl/tplimpl/template_ast_transformers.go

@@ -195,36 +195,9 @@ func (c *templateContext) wrapInPartialReturnWrapper(n *parse.ListNode) *parse.L
 
 }
 
-// The truth logic in Go's template package is broken for certain values
-// for the if and with keywords. This works around that problem by wrapping
-// the node passed to if/with in a getif conditional.
-// getif works slightly different than the Go built-in in that it also
-// considers any IsZero methods on the values (as in time.Time).
-// See https://github.com/gohugoio/hugo/issues/5738
-// TODO(bep) get rid of this.
-func (c *templateContext) wrapWithGetIf(p *parse.PipeNode) {
-	if len(p.Cmds) == 0 {
-		return
-	}
-
-	// getif will return an empty string if not evaluated as truthful,
-	// which is when we need the value in the with clause.
-	firstArg := parse.NewIdentifier("getif")
-	secondArg := p.CopyPipe()
-	newCmd := p.Cmds[0].Copy().(*parse.CommandNode)
-
-	// secondArg is a PipeNode and will behave as it was wrapped in parens, e.g:
-	// {{ getif (len .Params | eq 2) }}
-	newCmd.Args = []parse.Node{firstArg, secondArg}
-
-	p.Cmds = []*parse.CommandNode{newCmd}
-
-}
-
-// applyTransformations do 3 things:
-// 1) Wraps every with and if pipe in getif
-// 2) Parses partial return statement.
-// 3) Tracks template (partial) dependencies and some other info.
+// applyTransformations do 2 things:
+// 1) Parses partial return statement.
+// 2) Tracks template (partial) dependencies and some other info.
 func (c *templateContext) applyTransformations(n parse.Node) (bool, error) {
 	switch x := n.(type) {
 	case *parse.ListNode:
@@ -235,10 +208,8 @@ func (c *templateContext) applyTransformations(n parse.Node) (bool, error) {
 		c.applyTransformationsToNodes(x.Pipe)
 	case *parse.IfNode:
 		c.applyTransformationsToNodes(x.Pipe, x.List, x.ElseList)
-		c.wrapWithGetIf(x.Pipe)
 	case *parse.WithNode:
 		c.applyTransformationsToNodes(x.Pipe, x.List, x.ElseList)
-		c.wrapWithGetIf(x.Pipe)
 	case *parse.RangeNode:
 		c.applyTransformationsToNodes(x.Pipe, x.List, x.ElseList)
 	case *parse.TemplateNode:

tpl/tplimpl/template_ast_transformers_test.go

@@ -13,12 +13,9 @@
 package tplimpl
 
 import (
-	"strings"
-
 	"github.com/gohugoio/hugo/hugofs/files"
 
 	"testing"
-	"time"
 
 	template "github.com/gohugoio/hugo/tpl/internal/go_templates/htmltemplate"
 	"github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate/parse"
@@ -74,74 +71,6 @@ type T struct {
 func (T) Method0() {
 }
 
-func TestInsertIsZeroFunc(t *testing.T) {
-	t.Parallel()
-
-	c := qt.New(t)
-
-	var (
-		ctx = map[string]interface{}{
-			"True":     true,
-			"Now":      time.Now(),
-			"TimeZero": time.Time{},
-			"T":        &T{NonEmptyInterfaceTypedNil: (*T)(nil)},
-		}
-
-		templ1 = `
-{{ if .True }}.True: TRUE{{ else }}.True: FALSE{{ end }}
-{{ if .TimeZero }}.TimeZero1: TRUE{{ else }}.TimeZero1: FALSE{{ end }}
-{{ if (.TimeZero) }}.TimeZero2: TRUE{{ else }}.TimeZero2: FALSE{{ end }}
-{{ if not .TimeZero }}.TimeZero3: TRUE{{ else }}.TimeZero3: FALSE{{ end }}
-{{ if .Now }}.Now: TRUE{{ else }}.Now: FALSE{{ end }}
-{{ with .TimeZero }}.TimeZero1 with: {{ . }}{{ else }}.TimeZero1 with: FALSE{{ end }}
-{{ template "mytemplate" . }}
-{{ if .T.NonEmptyInterfaceTypedNil }}.NonEmptyInterfaceTypedNil: TRUE{{ else }}.NonEmptyInterfaceTypedNil: FALSE{{ end }}
-{{ template "other-file-template" . }}
-{{ define "mytemplate" }}
-{{ if .TimeZero }}.TimeZero1: mytemplate: TRUE{{ else }}.TimeZero1: mytemplate: FALSE{{ end }}
-{{ end }}
-`
-
-		// https://github.com/gohugoio/hugo/issues/5865
-		templ2 = `{{ define "other-file-template" }}
-{{ if .TimeZero }}.TimeZero1: other-file-template: TRUE{{ else }}.TimeZero1: other-file-template: FALSE{{ end }}
-{{ end }}		
-`
-	)
-
-	d := newD(c)
-	h := d.Tmpl.(*templateHandler)
-
-	// HTML templates
-	c.Assert(h.AddTemplate("mytemplate.html", templ1), qt.IsNil)
-	c.Assert(h.AddTemplate("othertemplate.html", templ2), qt.IsNil)
-
-	// Text templates
-	c.Assert(h.AddTemplate("_text/mytexttemplate.txt", templ1), qt.IsNil)
-	c.Assert(h.AddTemplate("_text/myothertexttemplate.txt", templ2), qt.IsNil)
-
-	c.Assert(h.markReady(), qt.IsNil)
-
-	for _, name := range []string{"mytemplate.html", "mytexttemplate.txt"} {
-		var sb strings.Builder
-		tt, _ := d.Tmpl.Lookup(name)
-		err := h.Execute(tt, &sb, ctx)
-		c.Assert(err, qt.IsNil)
-		result := sb.String()
-
-		c.Assert(result, qt.Contains, ".True: TRUE")
-		c.Assert(result, qt.Contains, ".TimeZero1: FALSE")
-		c.Assert(result, qt.Contains, ".TimeZero2: FALSE")
-		c.Assert(result, qt.Contains, ".TimeZero3: TRUE")
-		c.Assert(result, qt.Contains, ".Now: TRUE")
-		c.Assert(result, qt.Contains, "TimeZero1 with: FALSE")
-		c.Assert(result, qt.Contains, ".TimeZero1: mytemplate: FALSE")
-		c.Assert(result, qt.Contains, ".TimeZero1: other-file-template: FALSE")
-		c.Assert(result, qt.Contains, ".NonEmptyInterfaceTypedNil: FALSE")
-	}
-
-}
-
 func TestCollectInfo(t *testing.T) {
 
 	configStr := `{ "version": 42 }`