checker: check db type implements orm.Connection and isn't an Option. (#18078)

vlib/v/checker/orm.v

@@ -7,8 +7,9 @@ import v.token
 import v.util
 
 const (
-	fkey_attr_name = 'fkey'
-	v_orm_prefix   = 'V ORM'
+	fkey_attr_name            = 'fkey'
+	v_orm_prefix              = 'V ORM'
+	connection_interface_name = 'orm.Connection'
 )
 
 type ORMExpr = ast.SqlExpr | ast.SqlStmt
@@ -18,8 +19,13 @@ fn (mut c Checker) sql_expr(mut node ast.SqlExpr) ast.Type {
 	defer {
 		c.inside_sql = false
 	}
-	sym := c.table.sym(node.table_expr.typ)
+
+	if !c.check_db_expr(node.db_expr) {
+		return ast.void_type
+	}
 	c.ensure_type_exists(node.table_expr.typ, node.pos) or { return ast.void_type }
+	sym := c.table.sym(node.table_expr.typ)
+
 	old_ts := c.cur_orm_ts
 	c.cur_orm_ts = *sym
 	defer {
@@ -150,6 +156,9 @@ fn (mut c Checker) sql_expr(mut node ast.SqlExpr) ast.Type {
 }
 
 fn (mut c Checker) sql_stmt(mut node ast.SqlStmt) ast.Type {
+	if !c.check_db_expr(node.db_expr) {
+		return ast.void_type
+	}
 	node.db_expr_type = c.table.unaliased_type(c.expr(node.db_expr))
 
 	for mut line in node.lines {
@@ -496,3 +505,27 @@ fn (mut c Checker) check_orm_or_expr(expr ORMExpr) {
 		c.expected_or_type = ast.void_type
 	}
 }
+
+fn (mut c Checker) check_db_expr(db_expr &ast.Expr) bool {
+	connection_type_index := c.table.find_type_idx(checker.connection_interface_name)
+	connection_typ := ast.Type(connection_type_index)
+	db_expr_type := c.expr(db_expr)
+
+	// If we didn't find `orm.Connection`, we don't have any imported modules
+	// that depend on `orm` and implement the `orm.Connection` interface.
+	if connection_type_index == 0 {
+		c.error('expected a type that implements the `${checker.connection_interface_name}` interface',
+			db_expr.pos())
+		return false
+	}
+
+	is_implemented := c.type_implements(db_expr_type, connection_typ, db_expr.pos())
+	is_option := db_expr_type.has_flag(.option)
+
+	if is_implemented && is_option {
+		c.error(c.expected_msg(db_expr_type, db_expr_type.clear_flag(.option)), db_expr.pos())
+		return false
+	}
+
+	return true
+}

vlib/v/checker/tests/like_operator_with_non_string_type_error.out

@@ -1,14 +1,14 @@
-vlib/v/checker/tests/like_operator_with_non_string_type_error.vv:10:36: error: the right operand of the `like` operator must be a string type
-    8 | 
-    9 |     println(sql db {
-   10 |         select from User where name like 10
+vlib/v/checker/tests/like_operator_with_non_string_type_error.vv:12:36: error: the right operand of the `like` operator must be a string type
+   10 | 
+   11 |     println(sql db {
+   12 |         select from User where name like 10
       |                                          ~~
-   11 |     }!)
-   12 |
-vlib/v/checker/tests/like_operator_with_non_string_type_error.vv:14:26: error: the left operand of the `like` operator must be an identifier with a string type
-   12 | 
-   13 |     println(sql db {
-   14 |         select from User where 10 like true
+   13 |     }!)
+   14 |
+vlib/v/checker/tests/like_operator_with_non_string_type_error.vv:16:26: error: the left operand of the `like` operator must be an identifier with a string type
+   14 | 
+   15 |     println(sql db {
+   16 |         select from User where 10 like true
       |                                ~~
-   15 |     }!)
-   16 | }
+   17 |     }!)
+   18 | }

vlib/v/checker/tests/like_operator_with_non_string_type_error.vv

@@ -1,10 +1,12 @@
+import db.sqlite
+
 struct User {
 	id   int    [primary]
 	name string
 }
 
 fn main() {
-	db := ''
+	db := sqlite.connect(':memory:')!
 
 	println(sql db {
 		select from User where name like 10

vlib/v/checker/tests/orm_db_expr_option_error.out

@@ -0,0 +1,28 @@
+vlib/v/checker/tests/orm_db_expr_option_error.vv:16:11: error: expected `sqlite.DB`, not `?sqlite.DB`
+   14 |     db_option := connect_option()
+   15 | 
+   16 |     _ := sql db_option {
+      |              ~~~~~~~~~
+   17 |         select from Account
+   18 |     }!
+vlib/v/checker/tests/orm_db_expr_option_error.vv:22:11: error: `Account` doesn't implement method `select` of interface `orm.Connection`
+   20 |     account := Account{}
+   21 | 
+   22 |     _ := sql account {
+      |              ~~~~~~~
+   23 |         select from Account
+   24 |     }!
+vlib/v/checker/tests/orm_db_expr_option_error.vv:26:6: error: `Account` doesn't implement method `select` of interface `orm.Connection`
+   24 |     }!
+   25 | 
+   26 |     sql account {
+      |         ~~~~~~~
+   27 |         insert account into Account
+   28 |     }!
+vlib/v/checker/tests/orm_db_expr_option_error.vv:30:6: error: expected `sqlite.DB`, not `?sqlite.DB`
+   28 |     }!
+   29 | 
+   30 |     sql db_option {
+      |         ~~~~~~~~~
+   31 |         insert account into Account
+   32 |     }!

vlib/v/checker/tests/orm_db_expr_option_error.vv

@@ -0,0 +1,33 @@
+module main
+
+import db.sqlite
+
+struct Account {
+	id int [primary]
+}
+
+fn connect_option() ?sqlite.DB {
+	return sqlite.connect(':memory:') or { return none }
+}
+
+fn main() {
+	db_option := connect_option()
+
+	_ := sql db_option {
+		select from Account
+	}!
+
+	account := Account{}
+
+	_ := sql account {
+		select from Account
+	}!
+
+	sql account {
+		insert account into Account
+	}!
+
+	sql db_option {
+		insert account into Account
+	}!
+}

vlib/v/parser/tests/orm_no_error_handler.out

@@ -1,7 +1,7 @@
-vlib/v/parser/tests/orm_no_error_handler.vv:8:7: error: V ORM returns a result, so it should have either an `or {}` block, or `!` at the end
-    6 |     db := true
-    7 | 
-    8 |     _ := sql db {
+vlib/v/parser/tests/orm_no_error_handler.vv:10:7: error: V ORM returns a result, so it should have either an `or {}` block, or `!` at the end
+    8 |     db := sqlite.connect(':memory:')!
+    9 | 
+   10 |     _ := sql db {
       |          ~~~~~~~~
-    9 |         select from User
-   10 |     }
+   11 |         select from User
+   12 |     }

vlib/v/parser/tests/orm_no_error_handler.vv

@@ -1,9 +1,11 @@
+import db.sqlite
+
 struct User {
 	id int
 }
 
 fn main() {
-	db := true
+	db := sqlite.connect(':memory:')!
 
 	_ := sql db {
 		select from User