compare and convert system types properly (#2700)

Author: jycor

enginetest/queries/script_queries.go

@@ -7499,6 +7499,22 @@ where
 			},
 		},
 	},
+	{
+		Name: "coalesce with system types",
+		SetUpScript: []string{
+			"create table t as select @@admin_port as port1, @@port as port2, COALESCE(@@admin_port, @@port) as\n port3;",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query: "describe t;",
+				Expected: []sql.Row{
+					{"port1", "bigint", "NO", "", nil, ""},
+					{"port2", "bigint", "NO", "", nil, ""},
+					{"port3", "bigint", "NO", "", nil, ""},
+				},
+			},
+		},
+	},
 }
 
 var SpatialScriptTests = []ScriptTest{

sql/analyzer/resolve_create_select.go

@@ -31,6 +31,10 @@ func resolveCreateSelect(ctx *sql.Context, a *Analyzer, n sql.Node, scope *plan.
 	for i, col := range mergedSchema {
 		tempCol := *col
 		tempCol.Source = ct.Name()
+		// replace system variable types with their underlying types
+		if sysType, isSysTyp := tempCol.Type.(sql.SystemVariableType); isSysTyp {
+			tempCol.Type = sysType.UnderlyingType()
+		}
 		newSch[i] = &tempCol
 	}
 

sql/expression/function/coalesce.go

@@ -18,8 +18,9 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/dolthub/go-mysql-server/sql"
 	"github.com/dolthub/go-mysql-server/sql/expression"
+
+	"github.com/dolthub/go-mysql-server/sql"
 	"github.com/dolthub/go-mysql-server/sql/types"
 )
 
@@ -53,61 +54,73 @@ func (c *Coalesce) Description() string {
 // Type implements the sql.Expression interface.
 // The return type of Type() is the aggregated type of the argument types.
 func (c *Coalesce) Type() sql.Type {
-	typ := types.Null
-	for _, arg := range c.args {
+	retType := types.Null
+	for i, arg := range c.args {
 		if arg == nil {
 			continue
 		}
-		t := arg.Type()
+		argType := arg.Type()
+		if sysVarType, ok := argType.(sql.SystemVariableType); ok {
+			argType = sysVarType.UnderlyingType()
+		}
+		if i == 0 {
+			retType = argType
+			continue
+		}
+		if argType == nil || argType == types.Null {
+			continue
+		}
+		if retType.Equals(argType) {
+			continue
+		}
+
 		// special case for signed and unsigned integers
-		if (types.IsSigned(typ) && types.IsUnsigned(t)) || (types.IsUnsigned(typ) && types.IsSigned(t)) {
-			typ = types.MustCreateDecimalType(20, 0)
+		if (types.IsSigned(retType) && types.IsUnsigned(argType)) || (types.IsUnsigned(retType) && types.IsSigned(argType)) {
+			retType = types.MustCreateDecimalType(20, 0)
 			continue
 		}
 
-		if t != nil && t != types.Null {
-			convType := expression.GetConvertToType(typ, t)
-			switch convType {
-			case expression.ConvertToChar:
-				// special case for float64s
-				if (t == types.Float64 || typ == types.Float64) && !types.IsText(t) && !types.IsText(typ) {
-					typ = types.Float64
-					continue
-				}
-				// Can't get any larger than this
-				return types.LongText
-			case expression.ConvertToDecimal:
-				if typ == types.Float64 || t == types.Float64 {
-					typ = types.Float64
-				} else if types.IsDecimal(t) {
-					typ = t
-				} else if !types.IsDecimal(typ) {
-					typ = types.MustCreateDecimalType(10, 0)
-				}
-			case expression.ConvertToUnsigned:
-				if typ == types.Uint64 || t == types.Uint64 {
-					typ = types.Uint64
-				} else {
-					typ = types.Uint32
-				}
-			case expression.ConvertToSigned:
-				if typ == types.Int64 || t == types.Int64 {
-					typ = types.Int64
-				} else {
-					typ = types.Int32
-				}
-			case expression.ConvertToFloat:
-				if typ == types.Float64 || t == types.Float64 {
-					typ = types.Float64
-				} else {
-					typ = types.Float32
-				}
-			default:
+		convType := expression.GetConvertToType(retType, argType)
+		switch convType {
+		case expression.ConvertToChar:
+			// special case for float64s
+			if (argType == types.Float64 || retType == types.Float64) && !types.IsText(argType) && !types.IsText(retType) {
+				retType = types.Float64
+				continue
+			}
+			// Can't get any larger than this
+			return types.LongText
+		case expression.ConvertToDecimal:
+			if retType == types.Float64 || argType == types.Float64 {
+				retType = types.Float64
+			} else if types.IsDecimal(argType) {
+				retType = argType
+			} else if !types.IsDecimal(retType) {
+				retType = types.MustCreateDecimalType(10, 0)
+			}
+		case expression.ConvertToUnsigned:
+			if retType == types.Uint64 || argType == types.Uint64 {
+				retType = types.Uint64
+			} else {
+				retType = types.Uint32
+			}
+		case expression.ConvertToSigned:
+			if retType == types.Int64 || argType == types.Int64 {
+				retType = types.Int64
+			} else {
+				retType = types.Int32
+			}
+		case expression.ConvertToFloat:
+			if retType == types.Float64 || argType == types.Float64 {
+				retType = types.Float64
+			} else {
+				retType = types.Float32
 			}
+		default:
 		}
 	}
 
-	return typ
+	return retType
 }
 
 // CollationCoercibility implements the interface sql.CollationCoercible.

sql/expression/function/coalesce_test.go

@@ -152,17 +152,86 @@ func TestCoalesce(t *testing.T) {
 			typ:      types.Float64,
 			nullable: false,
 		},
+		{
+			name: "coalesce(sysInt, sysInt)",
+			input: []sql.Expression{
+				expression.NewLiteral(1, types.NewSystemIntType("int1", 0, 10, false)),
+				expression.NewLiteral(2, types.NewSystemIntType("int2", 0, 10, false)),
+			},
+			expected: 1,
+			typ:      types.Int64,
+			nullable: false,
+		},
+		{
+			name: "coalesce(sysInt, sysUint)",
+			input: []sql.Expression{
+				expression.NewLiteral(1, types.NewSystemIntType("int1", 0, 10, false)),
+				expression.NewLiteral(2, types.NewSystemUintType("int2", 0, 10)),
+			},
+			expected: 1,
+			typ:      types.MustCreateDecimalType(20, 0),
+			nullable: false,
+		},
+		{
+			name: "coalesce(sysUint, sysUint)",
+			input: []sql.Expression{
+				expression.NewLiteral(1, types.NewSystemUintType("int1", 0, 10)),
+				expression.NewLiteral(2, types.NewSystemUintType("int2", 0, 10)),
+			},
+			expected: 1,
+			typ:      types.Uint64,
+			nullable: false,
+		},
+		{
+			name: "coalesce(sysDouble, sysDouble)",
+			input: []sql.Expression{
+				expression.NewLiteral(1.0, types.NewSystemDoubleType("dbl1", 0.0, 10.0)),
+				expression.NewLiteral(2.0, types.NewSystemDoubleType("dbl2", 0.0, 10.0)),
+			},
+			expected: 1.0,
+			typ:      types.Float64,
+			nullable: false,
+		},
+		{
+			name: "coalesce(sysText)",
+			input: []sql.Expression{
+				expression.NewLiteral("abc", types.NewSystemStringType("str1")),
+			},
+			expected: "abc",
+			typ:      types.LongText,
+			nullable: false,
+		},
+		{
+			name: "coalesce(sysEnum)",
+			input: []sql.Expression{
+				expression.NewLiteral("abc", types.NewSystemEnumType("str1")),
+			},
+			expected: "abc",
+			typ:      types.EnumType{},
+			nullable: false,
+		},
+		{
+			name: "coalesce(sysSet)",
+			input: []sql.Expression{
+				expression.NewLiteral("abc", types.NewSystemSetType("str1", "abc")),
+			},
+			expected: "abc",
+			typ:      types.MustCreateSetType([]string{"abc"}, sql.Collation_Default),
+			nullable: false,
+		},
 	}
 
 	for _, tt := range testCases {
-		c, err := NewCoalesce(tt.input...)
-		require.NoError(t, err)
+		t.Run(tt.name, func(t *testing.T) {
+			c, err := NewCoalesce(tt.input...)
+			require.NoError(t, err)
 
-		require.Equal(t, tt.typ, c.Type())
-		require.Equal(t, tt.nullable, c.IsNullable())
-		v, err := c.Eval(sql.NewEmptyContext(), nil)
-		require.NoError(t, err)
-		require.Equal(t, tt.expected, v)
+			require.Equal(t, tt.typ, c.Type())
+			require.Equal(t, tt.nullable, c.IsNullable())
+			v, err := c.Eval(sql.NewEmptyContext(), nil)
+			require.NoError(t, err)
+			require.Equal(t, tt.expected, v)
+		})
 	}
 }
 

sql/types/typecheck.go

@@ -91,8 +91,10 @@ func IsNull(ex sql.Expression) bool {
 
 // IsNumber checks if t is a number type
 func IsNumber(t sql.Type) bool {
-	switch t.(type) {
-	case NumberTypeImpl_, DecimalType_, BitType_, YearType_, SystemBoolType:
+	switch typ := t.(type) {
+	case sql.SystemVariableType:
+		return IsNumber(typ.UnderlyingType())
+	case NumberTypeImpl_, DecimalType_, BitType_, YearType_:
 		return true
 	default:
 		return false
@@ -101,23 +103,25 @@ func IsNumber(t sql.Type) bool {
 
 // IsSigned checks if t is a signed type.
 func IsSigned(t sql.Type) bool {
-	// systemBoolType is Int8
-	if _, ok := t.(SystemBoolType); ok {
-		return true
+	if svt, ok := t.(sql.SystemVariableType); ok {
+		t = svt.UnderlyingType()
 	}
 	return t == Int8 || t == Int16 || t == Int24 || t == Int32 || t == Int64 || t == Boolean
 }
 
 // IsText checks if t is a CHAR, VARCHAR, TEXT, BINARY, VARBINARY, or BLOB (including TEXT and BLOB variants).
 func IsText(t sql.Type) bool {
-	if _, ok := t.(StringType); ok {
-		return ok
-	}
-	if extendedType, ok := t.(ExtendedType); ok {
-		_, isString := extendedType.Zero().(string)
+	switch typ := t.(type) {
+	case sql.SystemVariableType:
+		return IsText(typ.UnderlyingType())
+	case StringType:
+		return true
+	case ExtendedType:
+		_, isString := typ.Zero().(string)
 		return isString
+	default:
+		return false
 	}
-	return false
 }
 
 // IsTextBlob checks if t is one of the TEXTs or BLOBs.
@@ -178,14 +182,26 @@ func IsTimestampType(t sql.Type) bool {
 
 // IsEnum checks if t is a enum
 func IsEnum(t sql.Type) bool {
-	_, ok := t.(EnumType)
-	return ok
+	switch typ := t.(type) {
+	case sql.SystemVariableType:
+		return IsEnum(typ.UnderlyingType())
+	case EnumType:
+		return true
+	default:
+		return false
+	}
 }
 
 // IsSet checks if t is a set
 func IsSet(t sql.Type) bool {
-	_, ok := t.(SetType)
-	return ok
+	switch typ := t.(type) {
+	case sql.SystemVariableType:
+		return IsSet(typ.UnderlyingType())
+	case SetType:
+		return true
+	default:
+		return false
+	}
 }
 
 // IsTuple checks if t is a tuple type.
@@ -201,7 +217,6 @@ func IsUnsigned(t sql.Type) bool {
 	if svt, ok := t.(sql.SystemVariableType); ok {
 		t = svt.UnderlyingType()
 	}
-
 	return t == Uint8 || t == Uint16 || t == Uint24 || t == Uint32 || t == Uint64
 }