vweb: fix unused var warning

vlib/v/checker/checker.v

@@ -195,7 +195,7 @@ fn (mut c Checker) check_file_in_main(file ast.File) bool {
 }
 
 fn (mut c Checker) check_valid_snake_case(name, identifier string, pos token.Position) {
-	if name[0] == `_` {
+	if name[0] == `_` && !c.pref.is_vweb {
 		c.error('$identifier `$name` cannot start with `_`', pos)
 	}
 	if util.contains_capital(name) {
@@ -1765,14 +1765,14 @@ pub fn (c &Checker) unwrap_generic(typ table.Type) table.Type {
 
 // TODO node must be mut
 pub fn (mut c Checker) expr(node ast.Expr) table.Type {
-
 	c.expr_level++
-	defer { c.expr_level -- }
+	defer {
+		c.expr_level--
+	}
 	if c.expr_level > 200 {
 		c.error('checker: too many expr levels: $c.expr_level ', node.position())
 		return table.void_type
 	}
-
 	match mut node {
 		ast.AnonFn {
 			keep_fn := c.cur_fn
@@ -1851,7 +1851,12 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 		ast.ComptimeCall {
 			it.sym = c.table.get_type_symbol(c.unwrap_generic(c.expr(it.left)))
 			if it.is_vweb {
-				mut c2 := new_checker(c.table, c.pref)
+				x := *c.pref
+				xx := {
+					x |
+					is_vweb: true
+				} // TODO assoc parser bug
+				mut c2 := new_checker(c.table, xx)
 				c2.check(it.vweb_tmpl)
 				c.warnings << c2.warnings
 				c.errors << c2.errors
@@ -1953,7 +1958,8 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 			if !c.check_types(ltype, table.bool_type) {
 				ltype_sym := c.table.get_type_symbol(ltype)
 				lname := if it.is_likely { '_likely_' } else { '_unlikely_' }
-				c.error('`${lname}()` expects a boolean expression, instead it got `${ltype_sym.name}`', it.pos)
+				c.error('`${lname}()` expects a boolean expression, instead it got `${ltype_sym.name}`',
+					it.pos)
 			}
 			return table.bool_type
 		}

vlib/v/gen/comptime.v

@@ -18,7 +18,7 @@ fn (g &Gen) comptime_call(node ast.ComptimeCall) {
 				}
 			}
 		}
-		g.writeln('vweb__Context_html(&app->vweb, tmpl_res_$g.fn_decl.name)')
+		g.writeln('vweb__Context_html(&app->vweb, _tmpl_res_$g.fn_decl.name)')
 		return
 	}
 	g.writeln('// $' + 'method call. sym="$node.sym.name"')

vlib/v/pref/pref.v

@@ -112,6 +112,7 @@ pub mut:
 	use_color           ColorOutput // whether the warnings/errors should use ANSI color escapes.
 	is_parallel bool
 	error_limit int
+	is_vweb bool // skip _ var warning in templates
 }
 
 pub fn parse_args(args []string) (&Preferences, string) {

vlib/vweb/tmpl/tmpl.v

@@ -113,7 +113,7 @@ pub fn compile_template(content, fn_name string) string {
 		}
 	}
 	s.writeln(str_end)
-	s.writeln('tmpl_res_$fn_name := sb.str() ')
+	s.writeln('_tmpl_res_$fn_name := sb.str() ')
 	s.writeln('}')
 	s.writeln('// === end of vweb html template ===')
 	return s.str()