json.decode: fix expressions in the second argument, also fixes news_fetcher.v

Author: spytheman

examples/news_fetcher.v

@@ -11,7 +11,7 @@ struct Story {
 }
 
 fn worker_fetch(p &sync.PoolProcessor, cursor int, worker_id int) voidptr {
-	id := p.get_item<int>(cursor)
+	id := p.get_int_item(cursor)
 	resp := http.get('https://hacker-news.firebaseio.com/v0/item/${id}.json') or {
 		println('failed to fetch data from /v0/item/${id}.json')
 		return sync.no_result
@@ -45,5 +45,5 @@ fn main() {
 	// cases is what you want anyway... You can override the automatic choice
 	// by setting the VJOBS environment variable too.
 	// fetcher_pool.set_max_jobs( 4 )
-	fetcher_pool.work_on_items(ids)
+	fetcher_pool.work_on_items_i(ids)
 }

vlib/v/checker/checker.v

@@ -759,6 +759,8 @@ pub fn (mut c Checker) call_fn(call_expr mut ast.CallExpr) table.Type {
 			c.error('json.decode: first argument needs to be a type, got `$typ`', call_expr.pos)
 			return table.void_type
 		}
+		c.expected_type = table.string_type
+		call_expr.args[1].typ = c.expr(call_expr.args[1].expr)
 		typ := expr as ast.Type
 		return typ.typ.set_flag(.optional)
 	}

vlib/v/gen/cgen.v

@@ -1270,7 +1270,7 @@ fn (mut g Gen) expr(node ast.Expr) {
 				g.write('.')
 			}
 			if it.expr_type == 0 {
-				verror('cgen: SelectorExpr typ=0 field=$it.field $g.file.path $it.pos.line_nr')
+				verror('cgen: SelectorExpr | expr_type: 0 | it.expr: `${it.expr}` | field: `$it.field` | file: $g.file.path | line: $it.pos.line_nr')
 			}
 			g.write(c_name(it.field))
 		}