tools: support cmd/tools/.disable_autorecompilation in v up and v self too

cmd/tools/vself.v

@@ -3,10 +3,12 @@ module main
 import os
 import os.cmdline
 import v.pref
+import v.util.recompilation
 
 fn main() {
 	vexe := pref.vexe_path()
 	vroot := os.dir(vexe)
+	recompilation.must_be_enabled(vroot, 'Please install V from source, to use `v self` .')
 	os.chdir(vroot)
 	os.setenv('VCOLORS', 'always', true)
 	self_idx := os.args.index('self')

cmd/tools/vup.v

@@ -3,6 +3,7 @@ module main
 import os
 import v.pref
 import v.util
+import v.util.recompilation
 
 struct App {
 	is_verbose bool
@@ -12,15 +13,17 @@ struct App {
 
 fn new_app() App {
 	vexe := os.real_path(pref.vexe_path())
+	vroot := os.dir(vexe)
 	return App{
 		is_verbose: '-v' in os.args
 		vexe: vexe
-		vroot: os.dir(vexe)
+		vroot: vroot
 	}
 }
 
 fn main() {
 	app := new_app()
+	recompilation.must_be_enabled(app.vroot, 'Please install V from source, to use `v up` .')
 	os.chdir(app.vroot)
 	println('Updating V...')
 	app.update_from_master()

vlib/v/util/recompilation/recompilation.v

@@ -0,0 +1,26 @@
+module recompilation
+
+import os
+
+// disabling_file returns the path to a file, which if present, will disable the automatic recompilation
+// that V attempts, when it detects that itself is newer than a tool .v source file.
+// That file is intended to be made by `touch cmd/tools/.disable_autorecompilation` by package managers,
+// so that tools like `v up` and `v self` will not work anymore, instead they will direct users to install
+// V from source.
+pub fn disabling_file(vroot string) string {
+	tools_folder := os.join_path(vroot, 'cmd', 'tools')
+	res := os.join_path(tools_folder, '.disable_autorecompilation')
+	return res
+}
+
+// must_be_enabled is intended to be used by tools like `v self` and `v up`, to abort them
+// early, when they detect that the V installation is part of a distro package, that has disabled autorecompilation.
+pub fn must_be_enabled(vroot string, error_message string) {
+	file := disabling_file(vroot)
+	is_recompilation_disabled := os.exists(file)
+	if is_recompilation_disabled {
+		eprintln('Recompilation is disabled, since there is a "$file" file present.')
+		eprintln(error_message)
+		exit(1)
+	}
+}

vlib/v/util/util.v

@@ -7,6 +7,7 @@ import os
 import time
 import v.pref
 import v.vmod
+import v.util.recompilation
 
 pub const (
 	v_version = '0.2.1'
@@ -119,13 +120,23 @@ pub fn resolve_vroot(str string, dir string) ?string {
 	return str.replace('@VROOT', os.real_path(vmod_path))
 }
 
+// launch_tool - starts a V tool in a separate process, passing it the `args`.
+// All V tools are located in the cmd/tools folder, in files or folders prefixed by
+// the letter `v`, followed by the tool name, i.e. `cmd/tools/vdoc/` or `cmd/tools/vpm.v`.
+// The folder variant is suitable for larger and more complex tools, like `v doc`, because
+// it provides you the ability to split their source in separate .v files, organized by topic,
+// as well as have resources like static css/text/js files, that the tools can use.
+// launch_tool uses a timestamp based detection mechanism, so that after `v self`, each tool
+// will be recompiled too, before it is used, which guarantees that it would be up to date with
+// V itself. That mechanism can be disabled by package managers by creating/touching a small
+// `cmd/tools/.disable_autorecompilation` file, OR by changing the timestamps of all executables
+// in cmd/tools to be < 1024 seconds (in unix time).
 pub fn launch_tool(is_verbose bool, tool_name string, args []string) {
 	vexe := pref.vexe_path()
 	vroot := os.dir(vexe)
 	set_vroot_folder(vroot)
 	tool_args := args_quote_paths(args)
 	tools_folder := os.join_path(vroot, 'cmd', 'tools')
-	is_recompilation_disabled := os.exists(os.join_path(tools_folder, '.disable_autorecompilation'))
 	tool_basename := os.real_path(os.join_path(tools_folder, tool_name))
 	mut tool_exe := ''
 	mut tool_source := ''
@@ -144,11 +155,14 @@ pub fn launch_tool(is_verbose bool, tool_name string, args []string) {
 		println('launch_tool tool_source : $tool_source')
 		println('launch_tool tool_command: $tool_command')
 	}
-	should_compile := should_recompile_tool(vexe, tool_source, tool_name, tool_exe)
+	disabling_file := recompilation.disabling_file(vroot)
+	is_recompilation_disabled := os.exists(disabling_file)
+	should_compile := !is_recompilation_disabled &&
+		should_recompile_tool(vexe, tool_source, tool_name, tool_exe)
 	if is_verbose {
 		println('launch_tool should_compile: $should_compile')
 	}
-	if should_compile && !is_recompilation_disabled {
+	if should_compile {
 		emodules := external_module_dependencies_for_tool[tool_name]
 		for emodule in emodules {
 			check_module_is_installed(emodule, is_verbose) or { panic(err) }