cue/load: remove support for cue.mod files

We transitioned to a cue.mod directory with a cue.mod/module.cue file
all the way back in 2019: https://cue-review.googlesource.com/c/cue/+/3880

We continued supporting cue.mod files as if they were cue.mod/module.cue
during a transition period, to not break user's modules straight away.
It has been nearly five years now, and the fix is simple enough:

    mv cue.mod cue.mod-backup
    mkdir cue.mod
    mv cue.mod-backup cue.mod/module.cue

Remove support for the legacy file mode for good,
as well as a bit of code in `cue mod init` which did the rewrite above.
Note that a few tests still used it; update those accordingly.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I0a26f6153d58b9b60165e3060099f1d8eed2d4c0
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1188428
Reviewed-by: Roger Peppe <rogpeppe@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@gmail.com>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>

cmd/cue/cmd/fix.go

@@ -63,14 +63,10 @@ func runFixAll(cmd *Command, args []string) error {
 		args = []string{"./..."}
 
 		for {
-			if fi, err := os.Stat(filepath.Join(dir, "cue.mod")); err == nil {
-				if fi.IsDir() {
-					args = appendDirs(args, filepath.Join(dir, "cue.mod", "gen"))
-					args = appendDirs(args, filepath.Join(dir, "cue.mod", "pkg"))
-					args = appendDirs(args, filepath.Join(dir, "cue.mod", "usr"))
-				} else {
-					args = appendDirs(args, filepath.Join(dir, "pkg"))
-				}
+			if _, err := os.Stat(filepath.Join(dir, "cue.mod")); err == nil {
+				args = appendDirs(args, filepath.Join(dir, "cue.mod", "gen"))
+				args = appendDirs(args, filepath.Join(dir, "cue.mod", "pkg"))
+				args = appendDirs(args, filepath.Join(dir, "cue.mod", "usr"))
 				break
 			}
 

cmd/cue/cmd/mod.go

@@ -16,7 +16,6 @@ package cmd
 
 import (
 	"fmt"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"strings"
@@ -119,19 +118,10 @@ func runModInit(cmd *Command, args []string) (err error) {
 	}
 
 	mod := filepath.Join(cwd, "cue.mod")
-
-	info, err := os.Stat(mod)
-
-	// Detect old setups and backport it if requested.
-	if err == nil && !info.IsDir() {
-		// This path backports
-		if !flagForce.Bool(cmd) {
-			return fmt.Errorf("detected old-style config file; use --force to upgrade")
+	if info, err := os.Stat(mod); err == nil {
+		if !info.IsDir() {
+			return fmt.Errorf("cue.mod files are no longer supported; use cue.mod/module.cue")
 		}
-		return backport(mod, cwd)
-	}
-
-	if err == nil {
 		return fmt.Errorf("cue.mod directory already exists")
 	}
 	mf := &modfile.File{
@@ -166,40 +156,6 @@ func runModInit(cmd *Command, args []string) (err error) {
 	return err
 }
 
-// backport backports an old cue.mod setup to a new one.
-func backport(mod, cwd string) error {
-	tmp := filepath.Join(cwd, fmt.Sprintf("_%x_cue.mod", rand.Int()))
-	err := os.Rename(mod, tmp)
-	if err != nil {
-		return err
-	}
-
-	err = os.Mkdir(filepath.Join(cwd, "cue.mod"), 0755)
-	if err != nil {
-		os.Rename(tmp, mod)
-		return err
-	}
-
-	err = os.Rename(tmp, filepath.Join(cwd, "cue.mod", "module.cue"))
-	if err != nil {
-		return err
-	}
-
-	err = os.Rename(filepath.Join(cwd, "pkg"), filepath.Join(cwd, "cue.mod", "gen"))
-	if err != nil && !os.IsNotExist(err) {
-		return err
-	}
-
-	if err = os.Mkdir(filepath.Join(mod, "usr"), 0755); err != nil {
-		return err
-	}
-	if err = os.Mkdir(filepath.Join(mod, "pkg"), 0755); err != nil {
-		return err
-	}
-
-	return nil
-}
-
 func versionForModFile() string {
 	version := cueVersion()
 	if gomodule.IsPseudoVersion(version) {

cmd/cue/cmd/testdata/script/cmd_after.txtar

@@ -48,4 +48,4 @@ command: after: {
 -- task.cue --
 package home
 
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_concurrent.txtar

@@ -28,4 +28,4 @@ command: runtwo: {
 		text: "foo: \(foo.stdout)\nbar: \(bar.stdout)"
 	}
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_dep.txtar

@@ -30,4 +30,4 @@ command: do: {
     }
 }
 
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_dir.txtar

@@ -25,4 +25,4 @@ command: ls: {
 	}
 }
 
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_import.txtar

@@ -15,4 +15,4 @@ command: pkg: {
 	}
 }
 
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_mkdirtmp.txtar

@@ -17,4 +17,4 @@ command: mkdirtmp: {
 		success: true
 	}
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_print.txtar

@@ -34,4 +34,4 @@ command: print: {
 }
 -- task.cue --
 package home
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_ref.txtar

@@ -25,4 +25,4 @@ command: ref: {
 
 -- task.cue --
 package home
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/cmd_stdin.txtar

@@ -86,4 +86,4 @@ command: noreads: {
 		cmd: ["echo", "not reading any stdin"]
 	}
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/def_jsonschema.txtar

@@ -79,4 +79,4 @@ age: conflicting values "twenty" and int (mismatched types string and int):
 age: conflicting values "twenty" and int (mismatched types string and int):
     ./data.yaml:1:6
     ./schema.json:18:7
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/def_proto.txtar

@@ -218,4 +218,4 @@ message Timestamp {
   int32 nanos = 2;
 }
 
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/eval_context.txtar

@@ -26,4 +26,4 @@ cmp stdout expect-stdout
     "kind": "Service",
     "@name": "elem3"
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/export.txtar

@@ -14,4 +14,4 @@ package hello
 
 $type:   "demo"
 message: "Hello \(#who)!" // who declared in data.cue
--- hello/cue.mod --
+-- hello/cue.mod/module.cue --

cmd/cue/cmd/testdata/script/export_err.txtar

@@ -45,4 +45,4 @@ a: b: [0, 1, {c: int}, 3]
 // Issue #553
 b: c: "hello"
 out: "d is \(b.d)"
--- exporterr/cue.mod --
+-- exporterr/cue.mod/module.cue --

cmd/cue/cmd/testdata/script/export_list.txtar

@@ -36,4 +36,4 @@ cmp stdout expect-stdout
     "name": "supplement\nfoo",
     "json": "[1, 2]"
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/export_yaml.txtar

@@ -18,4 +18,4 @@ test: {
 		command: ["foo", "bar"]
 	}
 }
--- hello/cue.mod --
+-- hello/cue.mod/module.cue --

cmd/cue/cmd/testdata/script/fmt.txtar

@@ -8,4 +8,4 @@ import a.b "foo"
 
 a: 2
 bb: 3
--- fmt/cue.mod --
+-- fmt/cue.mod/module.cue --

cmd/cue/cmd/testdata/script/fmt_stdin.txtar

@@ -8,4 +8,4 @@ a: {b: 3} // a comment
 -- expect-stdout --
 foo: 2
 a: {b: 3} // a comment
--- fmt/cue.mod --
+-- fmt/cue.mod/module.cue --

cmd/cue/cmd/testdata/script/get_go_types.txtar

@@ -26,7 +26,7 @@ go 1.21
 module mod.test
 
 go 1.21
--- cue.mod --
+-- cue.mod/module.cue --
 module: "mod.test"
 -- pkg1/alias.go --
 package pkg1

cmd/cue/cmd/testdata/script/help_cmd.txtar

@@ -1,7 +1,7 @@
 exec cue help cmd
 cmp stdout expect-stdout
 
--- cue.mod --
+-- cue.mod/module.cue --
 -- task_tool.cue --
 package home
 

cmd/cue/cmd/testdata/script/help_cmd_flags.txtar

@@ -4,7 +4,7 @@ cmp stdout expect-stdout
 exec cue cmd --help
 cmp stdout expect-stdout
 
--- cue.mod --
+-- cue.mod/module.cue --
 -- task_tool.cue --
 package home
 

cmd/cue/cmd/testdata/script/help_hello.txtar

@@ -1,7 +1,7 @@
 exec cue help cmd hello
 cmp stdout expect-stdout
 
--- cue.mod --
+-- cue.mod/module.cue --
 -- task_tool.cue --
 package home
 

cmd/cue/cmd/testdata/script/import_context.txtar

@@ -28,4 +28,4 @@ cmp stdout expect-stdout
     "kind": "Service",
     "@name": "elem3"
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/import_files.txtar

@@ -27,4 +27,4 @@ json: "[1, 2]"
     "name": "supplement\nfoo",
     "json": "[1, 2]"
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/import_list.txtar

@@ -53,7 +53,7 @@ deployment: [{
 [{"b": 2}]
 -- import3/data.json --
 [1]
--- cue.mod --
+-- cue.mod/module.cue --
 
 -- issue2721/empty.yaml --
 -- issue2721/empty.cue.golden --

cmd/cue/cmd/testdata/script/import_path.txtar

@@ -36,4 +36,4 @@ service: "supplement\nfoo": {
     "name": "supplement\nfoo",
     "json": "[1, 2]"
 }
--- cue.mod --
+-- cue.mod/module.cue --

cmd/cue/cmd/testdata/script/merge_interaction.txtar

@@ -23,7 +23,7 @@ command: dump: {
 		text: yaml.MarshalStream(objects)
 	}
 }
--- cue.mod --
+-- cue.mod/module.cue --
 
 -- expect-stdout --
 spec: {}

cmd/cue/cmd/testdata/script/trim.txtar

@@ -131,4 +131,4 @@ group: {
 
 	comp: baz: {} // TODO: remove: implied by comprehension above
 }
--- cue.mod --
+-- cue.mod/module.cue --

cue/load/config.go

@@ -16,6 +16,7 @@ package load
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"os"
 	"path/filepath"
@@ -407,11 +408,10 @@ func (c *Config) loadModule() error {
 	if cerr != nil {
 		return nil
 	}
-	// TODO remove support for legacy non-directory module.cue file
-	// by returning an error if info.IsDir is false.
-	if info.IsDir() {
-		mod = filepath.Join(mod, moduleFile)
+	if !info.IsDir() {
+		return fmt.Errorf("cue.mod files are no longer supported; use cue.mod/module.cue")
 	}
+	mod = filepath.Join(mod, moduleFile)
 	f, cerr := c.fileSystem.openFile(mod)
 	if cerr != nil {
 		return nil

cue/load/loader_test.go

@@ -394,7 +394,7 @@ func TestOverlays(t *testing.T) {
 	c := &Config{
 		Overlay: map[string]Source{
 			// Not necessary, but nice to add.
-			abs("cue.mod"): FromString(`module: "mod.test"`),
+			abs("cue.mod/module.cue"): FromString(`module: "mod.test"`),
 
 			abs("dir/top.cue"): FromBytes([]byte(`
 			   package top

encoding/gocode/testdata/gen.go

@@ -37,7 +37,7 @@ func main() {
 	}
 
 	for _, d := range dirs {
-		if !d.IsDir() {
+		if !d.IsDir() || d.Name() == "cue.mod" {
 			continue
 		}
 		dir := filepath.Join(cwd, "testdata")