pkg: make $id in tasks a reference to a hidden field

As suggested by Paul and Marcel, hidden fields are unique to a package,
so unlike regular fields like `$id` they cannot be replaced by
a field from a different package or a field from unmarshalled data.

For each of the task definitions, keep `$id` around for backwards
compatibility, but make it a reference to the new `_id`.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: I8d1d8ba765f782e2cb9d3f70612c7834fef53fa5
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1214986
Reviewed-by: Paul Jolly <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>

Author: mvdan

cmd/cue/cmd/testdata/script/cmd_baddisplay.txtar

@@ -5,7 +5,7 @@ cmp stderr cmd_baddisplay.out
 -- cmd_baddisplay.out --
 command.baddisplay.display.text: conflicting values 42 and string (mismatched types int and string):
     ./task_tool.cue:6:9
-    tool/cli:4:9
+    tool/cli:5:9
 -- task.cue --
 package home
 message: "Hello world!"

cmd/cue/cmd/testdata/script/cmd_err.txtar

@@ -5,12 +5,12 @@ cmp stderr cmd_badfields.out
 -- cmd_badfields.out --
 command.ref.task.display.contents: invalid bytes argument: non-concrete value (string|bytes):
     ./task_tool.cue:6:8
-    tool/file:17:3
+    tool/file:20:3
 command.ref.task.display.filename: invalid string argument: non-concrete value string:
     ./task_tool.cue:6:8
     ./task_tool.cue:7:9
-    tool/file:15:3
-    tool/file:15:16
+    tool/file:18:3
+    tool/file:18:16
 -- task_tool.cue --
 package home
 

cmd/cue/cmd/testdata/script/cmd_errpos.txtar

@@ -9,11 +9,11 @@ command.prompter.contents: invalid bytes argument: non-concrete value string:
     ./task_tool.cue:9:10
     ./task_tool.cue:12:13
     ./task_tool.cue:17:3
-    tool/file:11:3
+    tool/file:13:3
 command.prompter.filename: invalid string argument: non-concrete value string:
     ./task_tool.cue:9:10
-    tool/file:9:3
-    tool/file:9:16
+    tool/file:11:3
+    tool/file:11:16
 -- task_tool.cue --
 package foo
 

pkg/tool/cli/cli.cue

@@ -16,7 +16,8 @@ package cli
 
 // Print sends text to the stdout of the current process.
 Print: {
-	$id: *"tool/cli.Print" | "print" // for backwards compatibility
+	$id: _id
+	_id: *"tool/cli.Print" | "print" // for backwards compatibility
 
 	// text is the text to be printed.
 	text: string
@@ -30,7 +31,8 @@ Print: {
 //         response: bool
 //     })
 Ask: {
-	$id: "tool/cli.Ask"
+	$id: _id
+	_id: "tool/cli.Ask"
 
 	// prompt sends this message to the output.
 	prompt: string

pkg/tool/cli/pkg.go

@@ -16,7 +16,8 @@ package exec
 
 // Run executes a program with the given arguments.
 Run: {
-	$id: *"tool/exec.Run" | "exec" // exec for backwards compatibility
+	$id: _id
+	_id: *"tool/exec.Run" | "exec" // exec for backwards compatibility
 
 	// cmd is a non-empty list holding the program name to run
 	// and the arguments to be passed to it.

pkg/tool/exec/exec.cue

@@ -16,7 +16,8 @@ package file
 
 // Read reads the contents of a file.
 Read: {
-	$id: "tool/file.Read"
+	$id: _id
+	_id: "tool/file.Read"
 
 	// filename names the file to read.
 	//
@@ -32,7 +33,8 @@ Read: {
 
 // Append writes contents to the given file.
 Append: {
-	$id: "tool/file.Append"
+	$id: _id
+	_id: "tool/file.Append"
 
 	// filename names the file to append.
 	//
@@ -49,7 +51,8 @@ Append: {
 
 // Create writes contents to the given file.
 Create: {
-	$id: "tool/file.Create"
+	$id: _id
+	_id: "tool/file.Create"
 
 	// filename names the file to write.
 	//
@@ -66,7 +69,8 @@ Create: {
 
 // Glob returns a list of files.
 Glob: {
-	$id: "tool/file.Glob"
+	$id: _id
+	_id: "tool/file.Glob"
 
 	// glob specifies the pattern to match files with.
 	//
@@ -78,7 +82,8 @@ Glob: {
 
 // Mkdir creates a directory at the specified path.
 Mkdir: {
-	$id: "tool/file.Mkdir"
+	$id: _id
+	_id: "tool/file.Mkdir"
 
 	// The directory path to create.
 	// If path is already a directory, Mkdir does nothing.
@@ -105,7 +110,8 @@ MkdirAll: Mkdir & {
 // It is the caller's responsibility to remove the directory when it is no
 // longer needed.
 MkdirTemp: {
-	$id: "tool/file.MkdirTemp"
+	$id: _id
+	_id: "tool/file.MkdirTemp"
 
 	// The temporary directory is created in the directory specified by dir.
 	// If dir is the empty string, MkdirTemp uses the default directory for
@@ -123,7 +129,8 @@ MkdirTemp: {
 // RemoveAll removes path and any children it contains.
 // It removes everything it can but returns the first error it encounters.
 RemoveAll: {
-	$id: "tool/file.RemoveAll"
+	$id: _id
+	_id: "tool/file.RemoveAll"
 
 	// The path to remove.
 	// If the path does not exist, RemoveAll does nothing.

pkg/tool/exec/pkg.go

@@ -20,7 +20,8 @@ Put: Do & {method: "PUT"}
 Delete: Do & {method: "DELETE"}
 
 Do: {
-	$id: *"tool/http.Do" | "http" // http for backwards compatibility
+	$id: _id
+	_id: *"tool/http.Do" | "http" // http for backwards compatibility
 
 	method: string
 	url:    string // TODO: make url.URL type

pkg/tool/file/file.cue

@@ -27,21 +27,24 @@ Name: !="" & !~"^[$]"
 // To define a shorthand, define the shorthand as a new flag referring to
 // the flag of which it is a shorthand.
 Setenv: {
-	$id: "tool/os.Setenv"
+	$id: _id
+	_id: "tool/os.Setenv"
 
 	{[Name]: Value}
 }
 
 // Getenv gets and parses the specific command line variables.
 Getenv: {
-	$id: "tool/os.Getenv"
+	$id: _id
+	_id: "tool/os.Getenv"
 
 	{[Name]: Value}
 }
 
 // Environ populates a struct with all environment variables.
 Environ: {
-	$id: "tool/os.Environ"
+	$id: _id
+	_id: "tool/os.Environ"
 
 	// A map of all populated values.
 	// Individual entries may be specified ahead of time to enable
@@ -52,5 +55,6 @@ Environ: {
 
 // Clearenv clears all environment variables.
 Clearenv: {
-	$id: "tool/os.Clearenv"
+	$id: _id
+	_id: "tool/os.Clearenv"
 }