checker: fix orm bug, when a joined table field context replaced the original table field context

vlib/v/checker/orm.v

@@ -12,7 +12,11 @@ fn (mut c Checker) sql_expr(mut node ast.SqlExpr) ast.Type {
 	}
 	sym := c.table.sym(node.table_expr.typ)
 	c.ensure_type_exists(node.table_expr.typ, node.pos) or { return ast.void_type }
+	old_ts := c.cur_orm_ts
 	c.cur_orm_ts = *sym
+	defer {
+		c.cur_orm_ts = old_ts
+	}
 	if sym.info !is ast.Struct {
 		c.error('The table symbol `$sym.name` has to be a struct', node.table_expr.pos)
 		return ast.void_type
@@ -114,7 +118,11 @@ fn (mut c Checker) sql_stmt_line(mut node ast.SqlStmtLine) ast.Type {
 	}
 	c.ensure_type_exists(node.table_expr.typ, node.pos) or { return ast.void_type }
 	table_sym := c.table.sym(node.table_expr.typ)
+	old_ts := c.cur_orm_ts
 	c.cur_orm_ts = *table_sym
+	defer {
+		c.cur_orm_ts = old_ts
+	}
 	if table_sym.info !is ast.Struct {
 		c.error('unknown type `$table_sym.name`', node.pos)
 		return ast.void_type

vlib/v/tests/orm_joined_tables_select_test.v

@@ -0,0 +1,37 @@
+import sqlite
+
+struct VieterDb {
+	conn sqlite.DB
+}
+
+pub struct GitRepoArch {
+pub:
+	id      int [primary; sql: serial]
+	repo_id int [nonull]
+	// repo string
+	value string [nonull]
+}
+
+pub struct GitRepo {
+pub mut:
+	id   int           [optional; primary; sql: serial]
+	repo string        [nonull]
+	arch []GitRepoArch [fkey: 'repo_id']
+}
+
+pub fn (db &VieterDb) get_git_repos() []GitRepo {
+	// NB: the query here, uses the `repo` field on GitRepo,
+	// while GitRepo is joined to GitRepoArch,
+	// which does *not* have a `repo` field.
+	// When this test was added, the checker used `GitRepoArch`
+	// to check for `repo`'s presence (which is wrong), because of
+	// a lingering c.cur_orm_ts state. The fix was to save/restore c.cur_orm_ts .
+	res := sql db.conn {
+		select from GitRepo where repo == 'something' order by id
+	}
+	return res
+}
+
+fn test_compiles() {
+	assert true
+}