gopls/internal/server: add modify_tags command handler

Previously, the VSCode extension installed and
executed gomodifytags directly.
To reduce third-party dependencies in gopls, we are submitting a
change to gomodifytags to extract the functionality into a library
called by gopls (fatih/gomodifytags#117). Now, the extension will call the gopls.modify_tags
command and the command handler will invoke the modifytags package's
Apply() method.

Also adds basic code actions for adding and removing struct tags. This will be extended once we
implement a dialogue feature in gopls.

Change-Id: Idf130c95eec5d469a454cb6f21897629b3364b06
Reviewed-on: https://go-review.googlesource.com/c/tools/+/652495
Reviewed-by: Hongxiang Jiang <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: madelinekalil

gopls/go.mod

@@ -20,6 +20,9 @@ require (
 
 require (
 	github.com/BurntSushi/toml v1.4.1-0.20240526193622-a339e1f7089c // indirect
+	github.com/fatih/camelcase v1.0.0 // indirect
+	github.com/fatih/gomodifytags v1.17.1-0.20250423142747-f3939df9aa3c // indirect
+	github.com/fatih/structtag v1.2.0 // indirect
 	github.com/google/safehtml v0.1.0 // indirect
 	golang.org/x/exp/typeparams v0.0.0-20250218142911-aa4b98e5adaa // indirect
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect

gopls/go.sum

@@ -1,5 +1,15 @@
 github.com/BurntSushi/toml v1.4.1-0.20240526193622-a339e1f7089c h1:pxW6RcqyfI9/kWtOwnv/G+AzdKuy2ZrqINhenH4HyNs=
 github.com/BurntSushi/toml v1.4.1-0.20240526193622-a339e1f7089c/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
+github.com/fatih/camelcase v1.0.0 h1:hxNvNX/xYBp0ovncs8WyWZrOrpBNub/JfaMvbURyft8=
+github.com/fatih/camelcase v1.0.0/go.mod h1:yN2Sb0lFhZJUdVvtELVWefmrXpuZESvPmqwoZc+/fpc=
+github.com/fatih/gomodifytags v1.16.0 h1:B65npXIXSk44F6c1hZGE1NazSnt+eXvtdEOG2Uy+QdU=
+github.com/fatih/gomodifytags v1.16.0/go.mod h1:TbUyEjH1Zo0GkJd2Q52oVYqYcJ0eGNqG8bsiOb75P9c=
+github.com/fatih/gomodifytags v1.17.1-0.20250325171527-8c663b1c0765 h1:T+oCz1SRpqkn4meT0PiAX5vM8HcESrWvsAzyvy0Vdh0=
+github.com/fatih/gomodifytags v1.17.1-0.20250325171527-8c663b1c0765/go.mod h1:YVLagR57bBxMai8IAEc7V4E/MWUYi0oUutLrZcTcnI8=
+github.com/fatih/gomodifytags v1.17.1-0.20250423142747-f3939df9aa3c h1:dDSgAjoOMp8da3egfz0t2S+t8RGOpEmEXZubcGuc0Bg=
+github.com/fatih/gomodifytags v1.17.1-0.20250423142747-f3939df9aa3c/go.mod h1:YVLagR57bBxMai8IAEc7V4E/MWUYi0oUutLrZcTcnI8=
+github.com/fatih/structtag v1.2.0 h1:/OdNE99OxoI/PqaW/SuSK9uxxT3f/tcSZgon/ssNSx4=
+github.com/fatih/structtag v1.2.0/go.mod h1:mBJUNpUnHmRKrKlQQlmCrh5PuhftFbNv8Ys4/aAZl94=
 github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI=
 github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=

gopls/internal/golang/codeaction.go

@@ -27,6 +27,7 @@ import (
 	"golang.org/x/tools/gopls/internal/protocol"
 	"golang.org/x/tools/gopls/internal/protocol/command"
 	"golang.org/x/tools/gopls/internal/settings"
+	"golang.org/x/tools/internal/astutil/cursor"
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/imports"
 	"golang.org/x/tools/internal/typesinternal"
@@ -262,6 +263,8 @@ var codeActionProducers = [...]codeActionProducer{
 	{kind: settings.RefactorRewriteMoveParamRight, fn: refactorRewriteMoveParamRight, needPkg: true},
 	{kind: settings.RefactorRewriteSplitLines, fn: refactorRewriteSplitLines, needPkg: true},
 	{kind: settings.RefactorRewriteEliminateDotImport, fn: refactorRewriteEliminateDotImport, needPkg: true},
+	{kind: settings.RefactorRewriteAddTags, fn: refactorRewriteAddStructTags, needPkg: true},
+	{kind: settings.RefactorRewriteRemoveTags, fn: refactorRewriteRemoveStructTags, needPkg: true},
 	{kind: settings.GoplsDocFeatures, fn: goplsDocFeatures}, // offer this one last (#72742)
 
 	// Note: don't forget to update the allow-list in Server.CodeAction
@@ -810,6 +813,82 @@ func refactorRewriteFillSwitch(ctx context.Context, req *codeActionsRequest) err
 	return nil
 }
 
+// selectionContainsStructField returns true if the given struct contains a
+// field between start and end pos. If needsTag is true, it only returns true if
+// the struct field found contains a struct tag.
+func selectionContainsStructField(node *ast.StructType, start, end token.Pos, needsTag bool) bool {
+	for _, field := range node.Fields.List {
+		if start <= field.End() && end >= field.Pos() {
+			if !needsTag || field.Tag != nil {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// selectionContainsStruct returns true if there exists a struct containing
+// fields within start and end positions. If removeTags is true, it means the
+// current command is for remove tags rather than add tags, so we only return
+// true if the struct field found contains a struct tag to remove.
+func selectionContainsStruct(cursor cursor.Cursor, start, end token.Pos, removeTags bool) bool {
+	cur, ok := cursor.FindByPos(start, end)
+	if !ok {
+		return false
+	}
+	if _, ok := cur.Node().(*ast.StructType); ok {
+		return true
+	}
+
+	// Handles case where selection is within struct.
+	for c := range cur.Enclosing((*ast.StructType)(nil)) {
+		if selectionContainsStructField(c.Node().(*ast.StructType), start, end, removeTags) {
+			return true
+		}
+	}
+
+	// Handles case where selection contains struct but may contain other nodes, including other structs.
+	for c := range cur.Preorder((*ast.StructType)(nil)) {
+		node := c.Node().(*ast.StructType)
+		// Check that at least one field is located within the selection. If we are removing tags, that field
+		// must also have a struct tag, otherwise we do not provide the code action.
+		if selectionContainsStructField(node, start, end, removeTags) {
+			return true
+		}
+	}
+	return false
+}
+
+// refactorRewriteAddStructTags produces "Add struct tags" code actions.
+// See [server.commandHandler.ModifyTags] for command implementation.
+func refactorRewriteAddStructTags(ctx context.Context, req *codeActionsRequest) error {
+	if selectionContainsStruct(req.pgf.Cursor, req.start, req.end, false) {
+		// TODO(mkalil): Prompt user for modification args once we have dialogue capabilities.
+		cmdAdd := command.NewModifyTagsCommand("Add struct tags", command.ModifyTagsArgs{
+			URI:   req.loc.URI,
+			Range: req.loc.Range,
+			Add:   "json",
+		})
+		req.addCommandAction(cmdAdd, false)
+	}
+	return nil
+}
+
+// refactorRewriteRemoveStructTags produces "Remove struct tags" code actions.
+// See [server.commandHandler.ModifyTags] for command implementation.
+func refactorRewriteRemoveStructTags(ctx context.Context, req *codeActionsRequest) error {
+	// TODO(mkalil): Prompt user for modification args once we have dialogue capabilities.
+	if selectionContainsStruct(req.pgf.Cursor, req.start, req.end, true) {
+		cmdRemove := command.NewModifyTagsCommand("Remove struct tags", command.ModifyTagsArgs{
+			URI:   req.loc.URI,
+			Range: req.loc.Range,
+			Clear: true,
+		})
+		req.addCommandAction(cmdRemove, false)
+	}
+	return nil
+}
+
 // removableParameter returns paramInfo about a removable parameter indicated
 // by the given [start, end) range, or nil if no such removal is available.
 //

gopls/internal/licenses/gen-licenses.sh

@@ -25,9 +25,9 @@ END
 # are known to have the same license.
 mods=$(go list -deps -f '{{with .Module}}{{.Path}}{{end}}' golang.org/x/tools/gopls | sort -u | grep -v golang.org)
 for mod in $mods; do
-  # Find the license file, either LICENSE or COPYING, and add it to the result.
+  # Find the license file, either LICENSE, COPYING, or LICENSE.md and add it to the result.
   dir=$(go list -m -f {{.Dir}} $mod)
-  license=$(ls -1 $dir | grep -E -i '^(LICENSE|COPYING)$')
+  license=$(ls -1 $dir | grep -E -i '^(LICENSE|LICENSE.md|COPYING)?$')
   echo "-- $mod $license --" >> $tempfile
   echo >> $tempfile
   sed 's/^-- / &/' $dir/$license >> $tempfile

gopls/internal/licenses/licenses.go

@@ -30,6 +30,122 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 
+-- github.com/fatih/camelcase LICENSE.md --
+
+The MIT License (MIT)
+
+Copyright (c) 2015 Fatih Arslan
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+-- github.com/fatih/gomodifytags LICENSE --
+
+Copyright (c) 2017, Fatih Arslan
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of gomodifytags nor the names of its
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+-- github.com/fatih/structtag LICENSE --
+
+Copyright (c) 2017, Fatih Arslan
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of structtag nor the names of its
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+This software includes some portions from Go. Go is used under the terms of the
+BSD like license.
+
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+The Go gopher was designed by Renee French. http://reneefrench.blogspot.com/ The design is licensed under the Creative Commons 3.0 Attributions license. Read this article for more details: https://blog.golang.org/gopher
+
 -- github.com/google/go-cmp LICENSE --
 
 Copyright (c) 2017 The Go Authors. All rights reserved.

gopls/internal/protocol/command/command_gen.go

@@ -297,6 +297,9 @@ type Interface interface {
 
 	// PackageSymbols: Return information about symbols in the given file's package.
 	PackageSymbols(context.Context, PackageSymbolsArgs) (PackageSymbolsResult, error)
+
+	// ModifyTags: Add or remove struct tags on a given node.
+	ModifyTags(context.Context, ModifyTagsArgs) error
 }
 
 type RunTestsArgs struct {
@@ -830,3 +833,19 @@ type PackageSymbol struct {
 	// Index of this symbol's file in PackageSymbolsResult.Files
 	File int `json:"file,omitempty"`
 }
+
+// ModifyTagsArgs holds variables that determine how struct tags are modified.
+type ModifyTagsArgs struct {
+	URI                  protocol.DocumentURI // uri of the file to be modified
+	Range                protocol.Range       // range in the file for where to modify struct tags
+	Add                  string               // comma-separated list of tags to add; i.e. "json,xml"
+	AddOptions           string               // comma-separated list of options to add, per tag; i.e. "json=omitempty"
+	Remove               string               // comma-separated list of tags to remove
+	RemoveOptions        string               // comma-separated list of options to remove
+	Clear                bool                 // if set, clear all tags. tags are cleared before any new tags are added
+	ClearOptions         bool                 // if set, clear all tag options; options are cleared before any new options are added
+	Overwrite            bool                 // if set, replace existing tags when adding
+	SkipUnexportedFields bool                 // if set, do not modify tags on unexported struct fields
+	Transform            string               // transform rule for adding tags; i.e. "snakecase"
+	ValueFormat          string               // format for the tag's value, after transformation; for example "column:{field}"
+}