tpl: Support text/template/parse API change in go1.11

Thanks to @rjoleary for the investigation.

Fixes #4784

3 files changed, 136 insertions, 48 deletions

diff --git a/tpl/tplimpl/template_ast_transformers.go b/tpl/tplimpl/template_ast_transformers.go
index bbd0f28a4..f0899dcbc 100644
--- a/tpl/tplimpl/template_ast_transformers.go
+++ b/tpl/tplimpl/template_ast_transformers.go
@@ -91,54 +91,6 @@ func applyTemplateTransformers(templ *parse.Tree, lookupFn func(name string) *pa
 	return nil
 }
 
-// paramsKeysToLower is made purposely non-generic to make it not so tempting
-// to do more of these hard-to-maintain AST transformations.
-func (c *templateContext) paramsKeysToLower(n parse.Node) {
-	switch x := n.(type) {
-	case *parse.ListNode:
-		if x != nil {
-			c.paramsKeysToLowerForNodes(x.Nodes...)
-		}
-	case *parse.ActionNode:
-		c.paramsKeysToLowerForNodes(x.Pipe)
-	case *parse.IfNode:
-		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
-	case *parse.WithNode:
-		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
-	case *parse.RangeNode:
-		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
-	case *parse.TemplateNode:
-		subTempl := c.getIfNotVisited(x.Name)
-		if subTempl != nil {
-			c.paramsKeysToLowerForNodes(subTempl.Root)
-		}
-	case *parse.PipeNode:
-		for i, elem := range x.Decl {
-			if len(x.Cmds) > i {
-				// maps $site => .Site etc.
-				c.decl[elem.Ident[0]] = x.Cmds[i].String()
-			}
-		}
-
-		for _, cmd := range x.Cmds {
-			c.paramsKeysToLower(cmd)
-		}
-
-	case *parse.CommandNode:
-		for _, elem := range x.Args {
-			switch an := elem.(type) {
-			case *parse.FieldNode:
-				c.updateIdentsIfNeeded(an.Ident)
-			case *parse.VariableNode:
-				c.updateIdentsIfNeeded(an.Ident)
-			case *parse.PipeNode:
-				c.paramsKeysToLower(an)
-			}
-
-		}
-	}
-}
-
 func (c *templateContext) paramsKeysToLowerForNodes(nodes ...parse.Node) {
 	for _, node := range nodes {
 		c.paramsKeysToLower(node)
diff --git a/tpl/tplimpl/template_ast_transformers_go1_10.go b/tpl/tplimpl/template_ast_transformers_go1_10.go
new file mode 100644
index 000000000..4e2a34c9e
--- /dev/null
+++ b/tpl/tplimpl/template_ast_transformers_go1_10.go
@@ -0,0 +1,68 @@
+// Copyright 2016 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.
+
+// +build !go1.11
+
+package tplimpl
+
+import (
+	"text/template/parse"
+)
+
+// paramsKeysToLower is made purposely non-generic to make it not so tempting
+// to do more of these hard-to-maintain AST transformations.
+func (c *templateContext) paramsKeysToLower(n parse.Node) {
+	switch x := n.(type) {
+	case *parse.ListNode:
+		if x != nil {
+			c.paramsKeysToLowerForNodes(x.Nodes...)
+		}
+	case *parse.ActionNode:
+		c.paramsKeysToLowerForNodes(x.Pipe)
+	case *parse.IfNode:
+		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
+	case *parse.WithNode:
+		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
+	case *parse.RangeNode:
+		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
+	case *parse.TemplateNode:
+		subTempl := c.getIfNotVisited(x.Name)
+		if subTempl != nil {
+			c.paramsKeysToLowerForNodes(subTempl.Root)
+		}
+	case *parse.PipeNode:
+		for i, elem := range x.Decl {
+			if len(x.Cmds) > i {
+				// maps $site => .Site etc.
+				c.decl[elem.Ident[0]] = x.Cmds[i].String()
+			}
+		}
+
+		for _, cmd := range x.Cmds {
+			c.paramsKeysToLower(cmd)
+		}
+
+	case *parse.CommandNode:
+		for _, elem := range x.Args {
+			switch an := elem.(type) {
+			case *parse.FieldNode:
+				c.updateIdentsIfNeeded(an.Ident)
+			case *parse.VariableNode:
+				c.updateIdentsIfNeeded(an.Ident)
+			case *parse.PipeNode:
+				c.paramsKeysToLower(an)
+			}
+
+		}
+	}
+}
diff --git a/tpl/tplimpl/template_ast_transformers_go1_11.go b/tpl/tplimpl/template_ast_transformers_go1_11.go
new file mode 100644
index 000000000..d7fdada0d
--- /dev/null
+++ b/tpl/tplimpl/template_ast_transformers_go1_11.go
@@ -0,0 +1,68 @@
+// Copyright 2016 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.
+
+// +build go1.11
+
+package tplimpl
+
+import (
+	"text/template/parse"
+)
+
+// paramsKeysToLower is made purposely non-generic to make it not so tempting
+// to do more of these hard-to-maintain AST transformations.
+func (c *templateContext) paramsKeysToLower(n parse.Node) {
+	switch x := n.(type) {
+	case *parse.ListNode:
+		if x != nil {
+			c.paramsKeysToLowerForNodes(x.Nodes...)
+		}
+	case *parse.ActionNode:
+		c.paramsKeysToLowerForNodes(x.Pipe)
+	case *parse.IfNode:
+		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
+	case *parse.WithNode:
+		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
+	case *parse.RangeNode:
+		c.paramsKeysToLowerForNodes(x.Pipe, x.List, x.ElseList)
+	case *parse.TemplateNode:
+		subTempl := c.getIfNotVisited(x.Name)
+		if subTempl != nil {
+			c.paramsKeysToLowerForNodes(subTempl.Root)
+		}
+	case *parse.PipeNode:
+		for i, elem := range x.Vars {
+			if len(x.Cmds) > i {
+				// maps $site => .Site etc.
+				c.decl[elem.Ident[0]] = x.Cmds[i].String()
+			}
+		}
+
+		for _, cmd := range x.Cmds {
+			c.paramsKeysToLower(cmd)
+		}
+
+	case *parse.CommandNode:
+		for _, elem := range x.Args {
+			switch an := elem.(type) {
+			case *parse.FieldNode:
+				c.updateIdentsIfNeeded(an.Ident)
+			case *parse.AssignNode:
+				c.updateIdentsIfNeeded(an.Ident)
+			case *parse.PipeNode:
+				c.paramsKeysToLower(an)
+			}
+
+		}
+	}
+}