Fix #201.

driver/driver.go

@@ -379,7 +379,7 @@ func (c *conn) PrepareContext(ctx context.Context, query string) (driver.Stmt, e
 	if err != nil {
 		return nil, err
 	}
-	if tail != "" {
+	if notWhitespace(tail) {
 		s.Close()
 		return nil, util.TailErr
 	}

driver/driver_test.go

@@ -225,8 +225,8 @@ func Test_Prepare(t *testing.T) {
 	}
 
 	_, err = db.Prepare(`SELECT 1; `)
-	if err.Error() != string(util.TailErr) {
-		t.Error("want tailErr")
+	if err != nil {
+		t.Error(err)
 	}
 
 	_, err = db.Prepare(`SELECT 1; SELECT`)

driver/time_test.go

@@ -27,12 +27,12 @@ func Fuzz_stringOrTime_1(f *testing.F) {
 			// Make sure times round-trip to the same string:
 			// https://pkg.go.dev/database/sql#Rows.Scan
 			if v.Format(time.RFC3339Nano) != str {
-				t.Fatalf("did not round-trip: %q", str)
+				t.Errorf("did not round-trip: %q", str)
 			}
 		} else {
 			date, err := time.Parse(time.RFC3339Nano, str)
 			if err == nil && date.Format(time.RFC3339Nano) == str {
-				t.Fatalf("would round-trip: %q", str)
+				t.Errorf("would round-trip: %q", str)
 			}
 		}
 	})

driver/whitespace.go

@@ -0,0 +1,67 @@
+package driver
+
+func notWhitespace(sql string) bool {
+	const (
+		code = iota
+		minus
+		slash
+		ccomment
+		endcomment
+		sqlcomment
+	)
+
+	state := code
+	for _, b := range ([]byte)(sql) {
+		if b == 0 {
+			break
+		}
+
+		switch state {
+		case code:
+			switch b {
+			case '-':
+				state = minus
+			case '/':
+				state = slash
+			case ' ', ';', '\t', '\n', '\v', '\f', '\r':
+				continue
+			default:
+				return true
+			}
+		case minus:
+			if b != '-' {
+				return true
+			}
+			state = sqlcomment
+		case slash:
+			if b != '*' {
+				return true
+			}
+			state = ccomment
+		case ccomment:
+			if b == '*' {
+				state = endcomment
+			}
+		case endcomment:
+			switch b {
+			case '/':
+				state = code
+			case '*':
+				state = endcomment
+			default:
+				state = ccomment
+			}
+		case sqlcomment:
+			if b == '\n' {
+				state = code
+			}
+		}
+	}
+
+	switch state {
+	case code, ccomment, endcomment, sqlcomment:
+		return false
+	default:
+		return true
+	}
+}

driver/whitespace_test.go

@@ -0,0 +1,56 @@
+package driver
+
+import (
+	"context"
+	"testing"
+)
+
+func Fuzz_isWhitespace(f *testing.F) {
+	f.Add("")
+	f.Add(" ")
+	f.Add(";")
+	f.Add("0")
+	f.Add("-")
+	f.Add("--")
+	f.Add("/*")
+	f.Add("/*/")
+	f.Add("/**")
+	f.Add("/**0/")
+	f.Add("\v")
+	f.Add(" \v")
+	f.Add("\xf0")
+
+	db, err := Open(":memory:")
+	if err != nil {
+		f.Fatal(err)
+	}
+	defer db.Close()
+
+	f.Fuzz(func(t *testing.T, str string) {
+		c, err := db.Conn(context.Background())
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		c.Raw(func(driverConn any) error {
+			conn := driverConn.(*conn).Conn
+			stmt, tail, err := conn.Prepare(str)
+			stmt.Close()
+
+			// It's hard to be bug for bug compatible with SQLite.
+			// We settle for somewhat less:
+			//   - if SQLite reports whitespace, we must too
+			//   - if we report whitespace, SQLite must not parse a statement
+			if notWhitespace(str) {
+				if stmt == nil && tail == "" && err == nil {
+					t.Errorf("was whitespace: %q", str)
+				}
+			} else {
+				if stmt != nil {
+					t.Errorf("was not whitespace: %q (%v)", str, err)
+				}
+			}
+			return nil
+		})
+	})
+}