fix: recognize MariaDB executable comments

Author: renecannao

include/sql_parser/tokenizer.h

@@ -160,7 +160,9 @@ class Tokenizer {
                     }
                 } else {
                     // MySQL: no nesting
-                    const bool executable = cursor_ < end_ && *cursor_ == '!';
+                    const bool executable = cursor_ < end_ &&
+                        (*cursor_ == '!' ||
+                         (cursor_ + 1 < end_ && cursor_[0] == 'M' && cursor_[1] == '!'));
                     bool has_user_variable_marker = false;
                     bool closed = false;
                     while (cursor_ < end_) {
@@ -176,9 +178,9 @@ class Tokenizer {
                         flag_fatal_error_at(StringRef{comment_start,
                             static_cast<uint32_t>(end_ - comment_start)});
                     }
-                    // Versioned comments execute as SQL on MySQL. Until their
-                    // contents are parsed exactly, preserve any possible user
-                    // variable use and force conservative classification.
+                    // MySQL and MariaDB executable comments run as SQL. Until
+                    // their contents are parsed exactly, preserve any possible
+                    // user variable use and force conservative classification.
                     if (executable && has_user_variable_marker) {
                         has_user_variables_ = true;
                         flag_fatal_error_at(StringRef{comment_start,

tests/test_tokenizer.cpp

@@ -213,6 +213,19 @@ TEST_F(MySQLTokenizerTest, UnterminatedBlockCommentIsAnError) {
     EXPECT_TRUE(tok.has_error());
 }
 
+TEST_F(MySQLTokenizerTest, MariaDBExecutableCommentsExposeUserVariables) {
+    const char* cases[] = {
+        "/*M!100100 SET @x=1 */",
+        "/*M! SET @x=1 */",
+    };
+    for (const char* sql : cases) {
+        SCOPED_TRACE(sql);
+        tok.reset(sql, strlen(sql));
+        while (tok.next_token().type != TokenType::TK_EOF) {}
+        EXPECT_TRUE(tok.has_user_variables());
+    }
+}
+
 TEST_F(MySQLTokenizerTest, Placeholder) {
     const char* sql = "?";
     tok.reset(sql, strlen(sql));

tests/test_user_variable.cpp

@@ -63,6 +63,10 @@ TEST(MySQLUserVariableUsage, HandlesMySQLCommentBoundariesConservatively) {
     EXPECT_EQ(classify("SELECT 1--@x"), UserVariableUsage::READ_ONLY);
     EXPECT_EQ(classify("/*!40101 SET @x=1 */"),
               UserVariableUsage::UNSAFE_OR_UNKNOWN);
+    EXPECT_EQ(classify("/*M!100100 SET @x=1 */"),
+              UserVariableUsage::UNSAFE_OR_UNKNOWN);
+    EXPECT_EQ(classify("/*M! SET @x=1 */"),
+              UserVariableUsage::UNSAFE_OR_UNKNOWN);
     EXPECT_EQ(classify("SELECT @x /* unterminated"),
               UserVariableUsage::UNSAFE_OR_UNKNOWN);
     EXPECT_EQ(classify("SET @x=1 /* unterminated"),