planner: check for decimal format in cast expr (#20836)

expression/integration_test.go

@@ -2195,7 +2195,6 @@ func (s *testIntegrationSuite) TestBuiltin(c *C) {
 	defer s.cleanEnv(c)
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
-	ctx := context.Background()
 
 	// for is true && is false
 	tk.MustExec("drop table if exists t")
@@ -2539,12 +2538,9 @@ func (s *testIntegrationSuite) TestBuiltin(c *C) {
 	c.Assert(err, NotNil)
 
 	// test case decimal precision less than the scale.
-	rs, err := tk.Exec("select cast(12.1 as decimal(3, 4));")
-	c.Assert(err, IsNil)
-	_, err = session.GetRows4Test(ctx, tk.Se, rs)
+	_, err = tk.Exec("select cast(12.1 as decimal(3, 4));")
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "[types:1427]For float(M,D), double(M,D) or decimal(M,D), M must be >= D (column '').")
-	c.Assert(rs.Close(), IsNil)
+	c.Assert(err.Error(), Equals, "[types:1427]For float(M,D), double(M,D) or decimal(M,D), M must be >= D (column '12.1').")
 
 	// test unhex and hex
 	result = tk.MustQuery("select unhex('4D7953514C')")

planner/core/preprocess.go

@@ -21,6 +21,7 @@ import (
 	"github.com/pingcap/errors"
 	"github.com/pingcap/parser"
 	"github.com/pingcap/parser/ast"
+	"github.com/pingcap/parser/format"
 	"github.com/pingcap/parser/model"
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/tidb/ddl"
@@ -29,7 +30,7 @@ import (
 	"github.com/pingcap/tidb/meta/autoid"
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/types"
-	"github.com/pingcap/tidb/types/parser_driver"
+	driver "github.com/pingcap/tidb/types/parser_driver"
 )
 
 // PreprocessOpt presents optional parameters to `Preprocess` method.
@@ -128,6 +129,8 @@ func (p *preprocessor) Enter(in ast.Node) (out ast.Node, skipChildren bool) {
 		// So skip check table name here, otherwise, recover table [table_name] syntax will return
 		// table not exists error. But recover table statement is use to recover the dropped table. So skip children here.
 		return in, true
+	case *ast.FuncCastExpr:
+		p.checkFuncCastExpr(node)
 	default:
 		p.flag &= ^parentIsJoin
 	}
@@ -776,3 +779,31 @@ func (p *preprocessor) resolveAlterTableStmt(node *ast.AlterTableStmt) {
 		}
 	}
 }
+
+func (p *preprocessor) checkFuncCastExpr(node *ast.FuncCastExpr) {
+	if node.Tp.EvalType() == types.ETDecimal {
+		if node.Tp.Flen >= node.Tp.Decimal && node.Tp.Flen <= mysql.MaxDecimalWidth && node.Tp.Decimal <= mysql.MaxDecimalScale {
+			// valid
+			return
+		}
+
+		var buf strings.Builder
+		restoreCtx := format.NewRestoreCtx(format.DefaultRestoreFlags, &buf)
+		if err := node.Expr.Restore(restoreCtx); err != nil {
+			p.err = err
+			return
+		}
+		if node.Tp.Flen < node.Tp.Decimal {
+			p.err = types.ErrMBiggerThanD.GenWithStackByArgs(buf.String())
+			return
+		}
+		if node.Tp.Flen > mysql.MaxDecimalWidth {
+			p.err = types.ErrTooBigPrecision.GenWithStackByArgs(node.Tp.Flen, buf.String(), mysql.MaxDecimalWidth)
+			return
+		}
+		if node.Tp.Decimal > mysql.MaxDecimalScale {
+			p.err = types.ErrTooBigScale.GenWithStackByArgs(node.Tp.Decimal, buf.String(), mysql.MaxDecimalScale)
+			return
+		}
+	}
+}

planner/core/preprocess_test.go

@@ -20,6 +20,7 @@ import (
 	"github.com/pingcap/errors"
 	"github.com/pingcap/parser"
 	"github.com/pingcap/parser/model"
+	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/parser/terror"
 	"github.com/pingcap/tidb/ddl"
 	"github.com/pingcap/tidb/infoschema"
@@ -206,6 +207,15 @@ func (s *testValidatorSuite) TestValidator(c *C) {
 		{"CREATE TABLE t1 (id INT NOT NULL, c1 VARCHAR(20) AS ('foo') VIRTUAL KEY NULL, PRIMARY KEY (id));", false, core.ErrUnsupportedOnGeneratedColumn},
 		{"CREATE TABLE t1 (id INT NOT NULL, c1 VARCHAR(20) AS ('foo') VIRTUAL KEY NOT NULL, PRIMARY KEY (id));", false, core.ErrUnsupportedOnGeneratedColumn},
 		{"create table t (a DOUBLE NULL, b_sto DOUBLE GENERATED ALWAYS AS (a + 2) STORED UNIQUE KEY NOT NULL PRIMARY KEY);", false, nil},
+
+		// issue 20295
+		// issue 11193
+		{"select cast(1.23 as decimal(65,65))", true, types.ErrTooBigScale.GenWithStackByArgs(65, "1.23", mysql.MaxDecimalScale)},
+		{"select CONVERT( 2, DECIMAL(62,60) )", true, types.ErrTooBigScale.GenWithStackByArgs(60, "2", mysql.MaxDecimalScale)},
+		{"select CONVERT( 2, DECIMAL(66,29) )", true, types.ErrTooBigPrecision.GenWithStackByArgs(66, "2", mysql.MaxDecimalWidth)},
+		{"select CONVERT( 2, DECIMAL(28,29) )", true, types.ErrMBiggerThanD.GenWithStackByArgs("2")},
+		{"select CONVERT( 2, DECIMAL(30,65) )", true, types.ErrMBiggerThanD.GenWithStackByArgs("2")},
+		{"select CONVERT( 2, DECIMAL(66,99) )", true, types.ErrMBiggerThanD.GenWithStackByArgs("2")},
 	}
 
 	store, dom, err := newStoreWithBootstrap()