checker: disallow `unsafe` map copy (#8720)

vlib/net/http/http.v

@@ -163,13 +163,12 @@ fn fetch_with_method(method Method, url string, _config FetchConfig) ?Response {
 
 fn build_url_from_fetch(_url string, config FetchConfig) ?string {
 	mut url := urllib.parse(_url) ?
-	params := unsafe {config.params}
-	if params.len == 0 {
+	if config.params.len == 0 {
 		return url.str()
 	}
-	mut pieces := []string{}
-	for key in params.keys() {
-		pieces << '$key=${params[key]}'
+	mut pieces := []string{cap: config.params.len}
+	for key, val in config.params {
+		pieces << '$key=$val'
 	}
 	mut query := pieces.join('&')
 	if url.raw_query.len > 1 {

vlib/v/checker/checker.v

@@ -2726,11 +2726,11 @@ pub fn (mut c Checker) assign_stmt(mut assign_stmt ast.AssignStmt) {
 			c.error('use `array2 $assign_stmt.op.str() array1.clone()` instead of `array2 $assign_stmt.op.str() array1` (or use `unsafe`)',
 				assign_stmt.pos)
 		}
-		if left_sym.kind == .map && !c.inside_unsafe && assign_stmt.op in [.assign, .decl_assign]
+		if left_sym.kind == .map && assign_stmt.op in [.assign, .decl_assign]
 			&& right_sym.kind == .map && !right_type.is_ptr() && !left.is_blank_ident()
 			&& right.is_lvalue() {
 			// Do not allow `a = b`
-			c.error('cannot copy map: call `move` or `clone` method first (or use `unsafe`)',
+			c.error('cannot copy map: call `move` or `clone` method (or use a reference)',
 				right.position())
 		}
 		left_is_ptr := left_type.is_ptr() || left_sym.is_pointer()

vlib/v/checker/tests/array_or_map_assign_err.out

@@ -12,14 +12,14 @@ vlib/v/checker/tests/array_or_map_assign_err.vv:5:5: error: use `array2 = array1
       |        ^
     6 | 
     7 |     m1 := {'one': 1}
-vlib/v/checker/tests/array_or_map_assign_err.vv:8:8: error: cannot copy map: call `move` or `clone` method first (or use `unsafe`)
+vlib/v/checker/tests/array_or_map_assign_err.vv:8:8: error: cannot copy map: call `move` or `clone` method (or use a reference)
     6 | 
     7 |     m1 := {'one': 1}
     8 |     m2 := m1
       |           ~~
     9 |     mut m3 := map[string]int{}
    10 |     m3 = m1
-vlib/v/checker/tests/array_or_map_assign_err.vv:10:7: error: cannot copy map: call `move` or `clone` method first (or use `unsafe`)
+vlib/v/checker/tests/array_or_map_assign_err.vv:10:7: error: cannot copy map: call `move` or `clone` method (or use a reference)
     8 |     m2 := m1
     9 |     mut m3 := map[string]int{}
    10 |     m3 = m1

vlib/v/gen/js/js.v

@@ -115,16 +115,18 @@ pub fn gen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 			out += '/** @namespace $name */\n'
 		}
 		out += 'const $name = (function ('
-		imports := unsafe {g.namespaces[node.name].imports}
-		for i, key in imports.keys() {
-			if i > 0 {
+		mut namespace := g.namespaces[node.name]
+		mut first := true
+		for _, val in namespace.imports {
+			if !first {
 				out += ', '
 			}
-			out += imports[key]
+			first = false
+			out += val
 		}
 		out += ') {\n\t'
 		// private scope
-		out += g.namespaces[node.name].out.str().trim_space()
+		out += namespace.out.str().trim_space()
 		// public scope
 		out += '\n'
 		if g.enable_doc {
@@ -137,21 +139,23 @@ pub fn gen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 				out += '\n\t\t$typ,'
 			}
 		}
-		for i, pub_var in g.namespaces[node.name].pub_vars {
+		for i, pub_var in namespace.pub_vars {
 			out += '\n\t\t$pub_var'
-			if i < g.namespaces[node.name].pub_vars.len - 1 {
+			if i < namespace.pub_vars.len - 1 {
 				out += ','
 			}
 		}
-		if g.namespaces[node.name].pub_vars.len > 0 {
+		if namespace.pub_vars.len > 0 {
 			out += '\n\t'
 		}
 		out += '};'
 		out += '\n})('
-		for i, key in imports.keys() {
-			if i > 0 {
+		first = true
+		for key, _ in namespace.imports {
+			if !first {
 				out += ', '
 			}
+			first = false
 			out += key.replace('.', '_')
 		}
 		out += ');\n'