Fix timezone parsing to support 3-component IANA names and hyphens

This commit fixes a parsing error in the MySQL SET statement parser that
occurred when processing `SET time_zone` statements with:

1. Three-component IANA timezone names (e.g., America/Argentina/Buenos_Aires)
2. Timezone names containing hyphens (e.g., America/Port-au-Prince)

Previously, the regex pattern `(?:\w+/\w+)` only matched 2-component
timezone names and did not support hyphens. This caused parsing errors
logged as:
  "[ERROR] Unable to parse query. If correct, report it as a bug:
   SET time_zone=\"America/Argentina/Buenos_Aires\";"

When multiplexing is enabled, this bug causes timestamps to be incorrectly
written to the database.

Changes:
- Updated timezone regex from `(?:\w+/\w+)` to `(?:[\w-]+(?:/[\w-]+){1,2})`
  - Supports 2-3 components: Area/Location or Area/Country/Location
  - Supports hyphens in component names (e.g., Port-au-Prince)
- Added comprehensive Doxygen documentation for timezone parsing
- Extended TAP test cases with new timezone formats

Note: Bare words like 'SYSTEM' and 'UTC' were already supported via
other patterns in the parser (vp2 pattern for word matching).

Fixes: #4993
Related: gemini-code-assist review comments

Author: renecannao

lib/MySQL_Set_Stmt_Parser.cpp

@@ -244,16 +244,58 @@ void MySQL_Set_Stmt_Parser::generateRE_parse1v2() {
 	vp = "(?:| *(?:\\+|\\-) *)\\d+(?:|\\.\\d+)"; // a signed or unsigned integer or decimal , N7 = merge of N3 and N6
 	var_patterns.push_back(vp);
 
+	/**
+	 * @page time_zone_parsing MySQL time_zone Variable Parsing
+	 *
+	 * The MySQL @c time_zone system variable accepts two formats:
+	 *
+	 * @section tz_numeric_format Numeric Offset Format
+	 * Specifies timezone as an offset from UTC in the format [+|-]HH:MM.
+	 * Examples: @c '+08:00' , @c '-05:30' , @c '+00:00' (UTC)
+	 *
+	 * @section tz_iana_format IANA Timezone Name Format
+	 * Specifies timezone using IANA timezone database names.
+	 * The naming convention follows the pattern @c Area/Location or
+	 * @c Area/Country/Location.
+	 *
+	 * @subsection tz_iana_components IANA Timezone Name Components
+	 * - **Area**: Continent, ocean, or special region (e.g., America, Europe, Asia, Etc)
+	 * - **Location**: City, island, or country name
+	 *
+	 * IANA timezone names may contain:
+	 * - Word characters (letters, digits, underscores): @c [a-zA-Z0-9_]
+	 * - Hyphens in place of spaces: @c Port-au-Prince , @c Rio_Gallegos
+	 *
+	 * @subsection tz_iana_examples IANA Timezone Examples
+	 * - 2 components: @c Europe/London , @c America/New_York , @c Asia/Tokyo
+	 * - 3 components: @c America/Argentina/Buenos_Aires , @c America/Indiana/Indianapolis
+	 * - With hyphens: @c America/Port-au-Prince , @c America/Blanc-Sablon
+	 *
+	 * @subsection tz_special_values Special Values
+	 * The following special values are also supported (matched by other patterns):
+	 * - @c SYSTEM : Use the system's timezone
+	 * - @c UTC : Coordinated Universal Time
+	 *
+	 * @subsection tz_limitations Limitations
+	 * The regex pattern limits matching to 2-3 components (e.g., @c Area/Location or
+	 * @c Area/Country/Location). While IANA timezone names with 4+ components are
+	 * theoretically possible, they are extremely rare and not currently supported.
+	 *
+	 * @see https://dev.mysql.com/doc/refman/8.0/en/time-zone-support.html
+	 * @see https://www.iana.org/time-zones
+	 */
 	{
-		// time_zone in numeric format:
-		// - +/- sign
-		// 1 or 2 digits
-		// :
-		// 2 digits
+		// time_zone in numeric format: [+|-]HH:MM
+		// Examples: '+08:00', '-05:30', '+00:00'
 		string tzd =  "(?:(?:\\+|\\-)(?:|\\d)\\d:\\d\\d)";
-		// time_zone in string format:
-		// word / word
-		string tzw =  "(?:\\w+/\\w+)";
+		// time_zone in string format: IANA timezone names
+		// Supports 2-3 components with optional hyphens:
+		//   - 2 components: Area/Location (e.g., Europe/London, America/New_York)
+		//   - 3 components: Area/Country/Location (e.g., America/Argentina/Buenos_Aires)
+		//   - With hyphens: America/Port-au-Prince, America/Blanc-Sablon
+		// Note: Does not match bare words like 'SYSTEM' or 'UTC' - these are matched
+		//       by other patterns in var_patterns (e.g., vp2 at line ~197)
+		string tzw =  "(?:[\\w-]+(?:/[\\w-]+){1,2})";
 		vp = "(?:" + tzd + "|" + tzw + ")"; // time_zone in numeric and string format
 	}
 	for (auto it = quote_symbol.begin(); it != quote_symbol.end(); it++) {

test/tap/tests/setparser_test_common.h

@@ -136,6 +136,7 @@ static Test syntax_errors[] = {
 };
 
 static Test time_zone[] = {
+  // Original tests - 2 component timezone names
   { "SET @@time_zone = 'Europe/Paris'", { Expected("time_zone",  {"Europe/Paris"}) } },
   { "SET @@time_zone = '+00:00'", { Expected("time_zone",  {"+00:00"}) } },
   { "SET @@time_zone = \"Europe/Paris\"", { Expected("time_zone",  {"Europe/Paris"}) } },
@@ -144,6 +145,24 @@ static Test time_zone[] = {
   { "SET @@TIME_ZONE = @OLD_TIME_ZONE", { Expected("time_zone",  {"@OLD_TIME_ZONE"}) } },
   { "SET @@TIME_ZONE := 'SYSTEM'", { Expected("time_zone",  {"SYSTEM"}) } },
   { "SET time_zone := 'SYSTEM'", { Expected("time_zone",  {"SYSTEM"}) } },
+  // Special values - UTC and SYSTEM
+  { "SET time_zone = 'UTC'", { Expected("time_zone",  {"UTC"}) } },
+  { "SET time_zone = SYSTEM", { Expected("time_zone",  {"SYSTEM"}) } },
+  { "SET time_zone = UTC", { Expected("time_zone",  {"UTC"}) } },
+  // 3 component timezone names (bug fix for GitHub issue #4993)
+  { "SET time_zone = 'America/Argentina/Buenos_Aires'", { Expected("time_zone",  {"America/Argentina/Buenos_Aires"}) } },
+  { "SET time_zone = 'America/Indiana/Indianapolis'", { Expected("time_zone",  {"America/Indiana/Indianapolis"}) } },
+  { "SET time_zone = \"America/Kentucky/Louisville\"", { Expected("time_zone",  {"America/Kentucky/Louisville"}) } },
+  // Timezone names with hyphens (additional fix)
+  { "SET time_zone = 'America/Port-au-Prince'", { Expected("time_zone",  {"America/Port-au-Prince"}) } },
+  { "SET time_zone = 'America/Blanc-Sablon'", { Expected("time_zone",  {"America/Blanc-Sablon"}) } },
+  { "SET time_zone = \"Atlantic/Canary\"", { Expected("time_zone",  {"Atlantic/Canary"}) } },
+  // Various numeric offsets
+  { "SET time_zone = '+08:00'", { Expected("time_zone",  {"+08:00"}) } },
+  { "SET time_zone = '-05:30'", { Expected("time_zone",  {"-05:30"}) } },
+  { "SET time_zone = '-10:00'", { Expected("time_zone",  {"-10:00"}) } },
+  // Combined with other SET variables
+  { "SET time_zone = 'America/Argentina/Buenos_Aires', sql_mode = 'TRADITIONAL'", { Expected("time_zone",  {"America/Argentina/Buenos_Aires"}), Expected("sql_mode", {"TRADITIONAL"}) } },
 };
 
 static Test session_track_gtids[] = {