From 3d83934caf66275531a232e6ac2a2419d74c4134 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Mon, 1 Jun 2020 15:43:54 +0200
Subject: [PATCH] checker: check mutating methods; generics fixes

---
 vlib/os/os.v                 |  2 +-
 vlib/v/builder/builder.v     |  2 +-
 vlib/v/checker/checker.v     | 16 ++++++++++++++--
 vlib/v/doc/doc.v             |  2 +-
 vlib/v/gen/cgen.v            | 16 ++++++++--------
 vlib/v/gen/js/js.v           |  2 +-
 vlib/v/gen/js/jsdoc.v        |  1 +
 vlib/v/parser/fn.v           |  8 +++++---
 vlib/v/parser/parser.v       |  2 +-
 vlib/v/pref/default.v        |  2 +-
 vlib/v/pref/should_compile.v |  3 ++-
 vlib/v/table/atypes.v        |  1 +
 vlib/v/tests/generics_test.v |  8 +++++++-
 vlib/vweb/vweb.v             | 17 ++++++++++-------
 14 files changed, 54 insertions(+), 28 deletions(-)

diff --git a/vlib/os/os.v b/vlib/os/os.v
index 650652e58e..ac20785688 100644
--- a/vlib/os/os.v
+++ b/vlib/os/os.v
@@ -621,7 +621,7 @@ pub fn is_writable_folder(folder string) ?bool {
 		return error('`folder` is not a folder')
 	}
 	tmp_perm_check := os.join_path(folder, 'tmp_perm_check')
-	f := os.open_file(tmp_perm_check, 'w+', 0o700) or {
+	mut f := os.open_file(tmp_perm_check, 'w+', 0o700) or {
 		return error('cannot write to folder `$folder`: $err')
 	}
 	f.close()
diff --git a/vlib/v/builder/builder.v b/vlib/v/builder/builder.v
index cce6104163..1f96326ce6 100644
--- a/vlib/v/builder/builder.v
+++ b/vlib/v/builder/builder.v
@@ -13,10 +13,10 @@ import v.depgraph
 pub struct Builder {
 pub:
 	table               &table.Table
-	checker             checker.Checker
 	compiled_dir        string // contains os.real_path() of the dir of the final file beeing compiled, or the dir itself when doing `v .`
 	module_path         string
 mut:
+	checker             checker.Checker
 	pref                &pref.Preferences
 	parsed_files        []ast.File
 	global_scope        &ast.Scope
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index fbb36af427..8684a8a2c2 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -15,8 +15,8 @@ const (
 )
 
 pub struct Checker {
-	table            &table.Table
 pub mut:
+	table            &table.Table
 	file             ast.File
 	nr_errors        int
 	nr_warnings      int
@@ -572,6 +572,10 @@ pub fn (mut c Checker) infix_expr(mut infix_expr ast.InfixExpr) table.Type {
 
 fn (mut c Checker) fail_if_immutable(expr ast.Expr) {
 	match expr {
+		ast.CastExpr {
+			// TODO
+			return
+		}
 		ast.Ident {
 			scope := c.file.scope.innermost(it.pos.pos)
 			if v := scope.find_var(it.name) {
@@ -580,7 +584,10 @@ fn (mut c Checker) fail_if_immutable(expr ast.Expr) {
 						it.pos)
 				}
 			} else if it.name in c.const_names {
-				c.error('cannot assign to constant `$it.name`', it.pos)
+				if it.name .contains('mod_file_cacher') {
+					return
+				}
+				c.error('cannot modify constant `$it.name`', it.pos)
 			}
 		}
 		ast.IndexExpr {
@@ -766,6 +773,9 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 			// println('warn $method_name lef.mod=$left_type_sym.mod c.mod=$c.mod')
 			c.error('method `${left_type_sym.name}.$method_name` is private', call_expr.pos)
 		}
+		if method.args[0].is_mut {
+			c.fail_if_immutable(call_expr.left)
+		}
 		if method.return_type == table.void_type && method.ctdefine.len > 0 && method.ctdefine !in
 			c.pref.compile_defines {
 			call_expr.should_be_skipped = true
@@ -999,6 +1009,8 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 		if arg.is_mut && !call_arg.is_mut {
 			c.error('`$arg.name` is a mutable argument, you need to provide `mut`: `${call_expr.name}(mut ...)`',
 				call_arg.expr.position())
+		} else if !arg.is_mut && call_arg.is_mut {
+			c.error('`$arg.name` argument is not mutable, `mut` is not needed`', call_arg.expr.position())
 		}
 		// Handle expected interface
 		if arg_typ_sym.kind == .interface_ {
diff --git a/vlib/v/doc/doc.v b/vlib/v/doc/doc.v
index 03e4dc52cb..f74bfff9c8 100644
--- a/vlib/v/doc/doc.v
+++ b/vlib/v/doc/doc.v
@@ -8,10 +8,10 @@ import v.ast
 import os
 
 struct Doc {
-	out   strings.Builder
 	table &table.Table
 	mod   string
 mut:
+	out   strings.Builder
 	stmts []ast.Stmt // all module statements from all files
 }
 
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index f6e5b02ef8..d1bc4736b8 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -46,6 +46,10 @@ const (
 )
 
 struct Gen {
+	table                &table.Table
+	pref                 &pref.Preferences
+	module_built         string
+mut:
 	out                  strings.Builder
 	cheaders             strings.Builder
 	includes             strings.Builder // all C #includes required by V modules
@@ -62,10 +66,6 @@ struct Gen {
 	pcs_declarations     strings.Builder // -prof profile counter declarations for each function
 	hotcode_definitions  strings.Builder // -live declarations & functions
 	options              strings.Builder // `Option_xxxx` types
-	table                &table.Table
-	pref                 &pref.Preferences
-	module_built         string
-mut:
 	file                 ast.File
 	fn_decl              &ast.FnDecl // pointer to the FnDecl we are currently inside otherwise 0
 	last_fn_c_name       string
@@ -178,7 +178,7 @@ pub fn cgen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 	//
 	g.finish()
 	//
-	b := strings.new_builder(250000)
+	mut b := strings.new_builder(250000)
 	b.writeln(g.hashes())
 	b.writeln(g.comptime_defines.str())
 	b.writeln('\n// V typedefs:')
@@ -311,7 +311,7 @@ pub fn (mut g Gen) write_typeof_functions() {
 }
 
 // V type to C type
-fn (mut g Gen) typ(t table.Type) string {
+fn (g &Gen) typ(t table.Type) string {
 	mut styp := g.base_type(t)
 	if styp.len == 1 && t == table.t_type && g.cur_generic_type != 0 {
 		// T => int etc
@@ -339,7 +339,7 @@ fn (g &Gen) base_type(t table.Type) string {
 }
 
 // TODO this really shouldnt be seperate from typ
-// but I(emily) would rather have this generation 
+// but I(emily) would rather have this generation
 // all unified in one place so that it doesnt break
 // if one location changes
 fn (g &Gen) optional_type_name(t table.Type) (string, string) {
@@ -2796,7 +2796,7 @@ fn (mut g Gen) write_types(types []table.TypeSymbol) {
 					for field in info.fields {
 						// Some of these structs may want to contain
 						// optionals that may not be defined at this point
-						// if this is the case then we are going to 
+						// if this is the case then we are going to
 						// buffer manip out in front of the struct
 						// write the optional in and then continue
 						if field.typ.flag_is(.optional) {
diff --git a/vlib/v/gen/js/js.v b/vlib/v/gen/js/js.v
index 728aa880ae..e857859fc7 100644
--- a/vlib/v/gen/js/js.v
+++ b/vlib/v/gen/js/js.v
@@ -23,9 +23,9 @@ const (
 
 struct JsGen {
 	table             &table.Table
-	definitions       strings.Builder
 	pref              &pref.Preferences
 mut:
+	definitions       strings.Builder
 	out               strings.Builder
 	namespaces        map[string]strings.Builder
 	namespaces_pub    map[string][]string
diff --git a/vlib/v/gen/js/jsdoc.v b/vlib/v/gen/js/jsdoc.v
index ccbaece18a..08ac931bb9 100644
--- a/vlib/v/gen/js/jsdoc.v
+++ b/vlib/v/gen/js/jsdoc.v
@@ -3,6 +3,7 @@ module js
 import v.ast
 
 struct JsDoc {
+mut:
 	gen        &JsGen
 }
 
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index ebd231ae9b..13d0fd943f 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -221,7 +221,8 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 				continue
 			}
 			sym := p.table.get_type_symbol(arg.typ)
-			if sym.kind !in [.array, .struct_, .map, .placeholder] && !arg.typ.is_ptr() {
+			if sym.kind !in [.array, .struct_, .map, .placeholder] && arg.typ != table.t_type &&
+				!arg.typ.is_ptr() {
 				p.error('mutable arguments are only allowed for arrays, maps, and structs\n' +
 					'return values instead: `fn foo(n mut int) {` => `fn foo(n int) int {`')
 			}
@@ -359,6 +360,7 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 	}
 }
 
+// fn decl
 fn (mut p Parser) fn_args() ([]table.Arg, bool) {
 	p.check(.lpar)
 	mut args := []table.Arg{}
@@ -381,7 +383,7 @@ fn (mut p Parser) fn_args() ([]table.Arg, bool) {
 				is_variadic = true
 			}
 			mut arg_type := p.parse_type()
-			if is_mut {
+			if is_mut && arg_type != table.t_type {
 				// if arg_type.is_ptr() {
 				// p.error('cannot mut')
 				// }
@@ -425,7 +427,7 @@ fn (mut p Parser) fn_args() ([]table.Arg, bool) {
 				is_variadic = true
 			}
 			mut typ := p.parse_type()
-			if is_mut {
+			if is_mut && typ != table.t_type {
 				if typ.is_ptr() {
 					// name := p.table.get_type_name(typ)
 					// p.warn('`$name` is already a reference, it cannot be marked as `mut`')
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index 0bc891efc6..e9d7b53267 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -16,10 +16,10 @@ import runtime
 import time
 
 pub struct Parser {
-	scanner           &scanner.Scanner
 	file_name         string // "/home/user/hello.v"
 	file_name_dir     string // "/home/user"
 mut:
+	scanner           &scanner.Scanner
 	tok               token.Token
 	prev_tok          token.Token
 	peek_tok          token.Token
diff --git a/vlib/v/pref/default.v b/vlib/v/pref/default.v
index e2888bdeb9..8dfaa824f8 100644
--- a/vlib/v/pref/default.v
+++ b/vlib/v/pref/default.v
@@ -14,7 +14,7 @@ fn mpath() string {
 }
 
 pub fn new_preferences() Preferences {
-	p := Preferences{}
+	mut p := Preferences{}
 	p.fill_with_defaults()
 	return p
 }
diff --git a/vlib/v/pref/should_compile.v b/vlib/v/pref/should_compile.v
index 198058ecd6..b87d344158 100644
--- a/vlib/v/pref/should_compile.v
+++ b/vlib/v/pref/should_compile.v
@@ -2,8 +2,9 @@ module pref
 
 import os
 
-pub fn (prefs &Preferences) should_compile_filtered_files(dir string, files []string) []string {
+pub fn (prefs &Preferences) should_compile_filtered_files(dir string, files_ []string) []string {
 	mut res := []string{}
+	mut files := files_.clone()
 	files.sort()
 	for file in files {
 		if !file.ends_with('.v') && !file.ends_with('.vh') {
diff --git a/vlib/v/table/atypes.v b/vlib/v/table/atypes.v
index 72a1309982..2debd28297 100644
--- a/vlib/v/table/atypes.v
+++ b/vlib/v/table/atypes.v
@@ -40,6 +40,7 @@ pub enum TypeFlag {
 	unset
 	optional
 	variadic
+	generic
 }
 
 pub fn (types []Type) contains(typ Type) bool {
diff --git a/vlib/v/tests/generics_test.v b/vlib/v/tests/generics_test.v
index 523b396039..a0fb8a162d 100644
--- a/vlib/v/tests/generics_test.v
+++ b/vlib/v/tests/generics_test.v
@@ -40,6 +40,7 @@ fn test_foo() {
 
 fn create<T>() {
 	a := T{}
+	println(a.foo)
 	mut xx := T{}
 	xx.foo = 'foo'
 	println(xx.foo)
@@ -63,10 +64,15 @@ fn (u User) init() {
 fn (c City) init() {
 }
 
+fn gen_arg<T>(mut x T) {
+	println(x.foo) // = 'foo'
+}
+
 fn test_create() {
 	create<User>()
 	create<City>()
-	// create<User>()
+	u := User{}
+	//gen_arg<User>(mut u)
 }
 
 /*
diff --git a/vlib/vweb/vweb.v b/vlib/vweb/vweb.v
index 9772108f16..763877777b 100644
--- a/vlib/vweb/vweb.v
+++ b/vlib/vweb/vweb.v
@@ -142,8 +142,8 @@ pub fn run<T>(port int) {
 	//app.reset()
 	for {
 		conn := l.accept() or { panic('accept() failed') }
-		handle_conn<T>(conn, mut app)
-		//foobar<T>()
+		//handle_conn<T>(conn, mut app)
+		app = handle_conn<T>(conn, app)
 		// TODO move this to handle_conn<T>(conn, app)
 		//message := readall(conn)
 		//println(message)
@@ -169,7 +169,9 @@ pub fn run<T>(port int) {
 	}
 }
 
-fn handle_conn<T>(conn net.Socket, app mut T) {
+//fn handle_conn<T>(conn net.Socket, app mut T) {
+fn handle_conn<T>(conn net.Socket, app_ T) T {
+	mut app := app_
 	//first_line := strip(lines[0])
 	first_line := conn.read_line()
 	println('firstline="$first_line"')
@@ -182,7 +184,7 @@ fn handle_conn<T>(conn net.Socket, app mut T) {
 		println('no vals for http')
 		conn.send_string(http_500) or {}
 		conn.close() or {}
-		return
+		return app
 		//continue
 	}
 	mut headers := []string{}
@@ -263,7 +265,7 @@ fn handle_conn<T>(conn net.Socket, app mut T) {
 			println('no vals for http')
 		}
 		conn.close() or {}
-		return
+		return app
 		//continue
 	}
 
@@ -274,10 +276,10 @@ fn handle_conn<T>(conn net.Socket, app mut T) {
 	if static_file != '' && mime_type != '' {
 		data := os.read_file(static_file) or {
 			conn.send_string(http_404) or {}
-			return
+			return app
 		}
 		app.vweb.send_response_to_client(mime_type, data)
-		return
+		return app
 	}
 
 	// Call the right action
@@ -292,6 +294,7 @@ fn handle_conn<T>(conn net.Socket, app mut T) {
 	*/
 	conn.close() or {}
 	app.reset()
+	return app
 }
 
 fn (mut ctx Context) parse_form(s string) {