fix(tsql): quote reserved-keyword aliases and translate niladic temporal expressions (CR-009)

src/ast/types.rs

@@ -636,6 +636,8 @@ pub enum TypedFunction {
     },
     /// `CURRENT_DATE`
     CurrentDate,
+    /// `CURRENT_TIME` — returns the current time of day (ANSI / PostgreSQL).
+    CurrentTime,
     /// `CURRENT_TIMESTAMP` / `NOW()` / `GETDATE()`
     CurrentTimestamp,
     /// `STR_TO_TIME(expr, format)` / `TO_TIMESTAMP` / `PARSE_DATETIME`
@@ -885,7 +887,9 @@ impl TypedFunction {
                 end.walk(visitor);
             }
             TypedFunction::DateTrunc { expr, .. } => expr.walk(visitor),
-            TypedFunction::CurrentDate | TypedFunction::CurrentTimestamp => {}
+            TypedFunction::CurrentDate
+            | TypedFunction::CurrentTime
+            | TypedFunction::CurrentTimestamp => {}
             TypedFunction::StrToTime { expr, format }
             | TypedFunction::TimeToStr { expr, format } => {
                 expr.walk(visitor);
@@ -1147,6 +1151,7 @@ impl TypedFunction {
                 unit,
             },
             TypedFunction::CurrentDate => TypedFunction::CurrentDate,
+            TypedFunction::CurrentTime => TypedFunction::CurrentTime,
             TypedFunction::CurrentTimestamp => TypedFunction::CurrentTimestamp,
             TypedFunction::StrToTime { expr, format } => TypedFunction::StrToTime {
                 expr: Box::new(expr.transform(func)),

src/dialects/mod.rs

@@ -261,10 +261,350 @@ fn is_hive_family(d: Dialect) -> bool {
 }
 
 /// Dialects in the T-SQL family.
-fn is_tsql_family(d: Dialect) -> bool {
+pub(crate) fn is_tsql_family(d: Dialect) -> bool {
     matches!(d, Dialect::Tsql | Dialect::Fabric)
 }
 
+/// Returns `true` when `name` (case-insensitive) is a T-SQL reserved keyword
+/// that must be quoted with square brackets when used as an identifier
+/// (e.g. as a column alias, table alias, or column name).
+///
+/// Sourced from Microsoft's documented T-SQL reserved words (current and
+/// future). Covers both the ANSI/ODBC reserved set and SQL Server's
+/// dialect-specific reservations. Not exhaustive for every contextual
+/// keyword — focuses on words that, when emitted unquoted as aliases, will
+/// cause MSSQL syntax error 156.
+#[must_use]
+pub(crate) fn is_tsql_reserved(name: &str) -> bool {
+    // Reserved word set — keep in sorted order for binary_search.
+    // Source: docs.microsoft.com "Reserved Keywords (Transact-SQL)" and
+    // "ODBC Reserved Keywords", plus ANSI/ISO future reserved words.
+    const RESERVED: &[&str] = &[
+        "ABSOLUTE",
+        "ACTION",
+        "ADA",
+        "ADD",
+        "ALL",
+        "ALLOCATE",
+        "ALTER",
+        "AND",
+        "ANY",
+        "ARE",
+        "AS",
+        "ASC",
+        "ASSERTION",
+        "AT",
+        "AUTHORIZATION",
+        "AVG",
+        "BACKUP",
+        "BEGIN",
+        "BETWEEN",
+        "BIT",
+        "BIT_LENGTH",
+        "BOTH",
+        "BREAK",
+        "BROWSE",
+        "BULK",
+        "BY",
+        "CASCADE",
+        "CASCADED",
+        "CASE",
+        "CAST",
+        "CATALOG",
+        "CHAR",
+        "CHARACTER",
+        "CHARACTER_LENGTH",
+        "CHAR_LENGTH",
+        "CHECK",
+        "CHECKPOINT",
+        "CLOSE",
+        "CLUSTERED",
+        "COALESCE",
+        "COLLATE",
+        "COLLATION",
+        "COLUMN",
+        "COMMIT",
+        "COMPUTE",
+        "CONNECT",
+        "CONNECTION",
+        "CONSTRAINT",
+        "CONSTRAINTS",
+        "CONTAINS",
+        "CONTAINSTABLE",
+        "CONTINUE",
+        "CONVERT",
+        "CORRESPONDING",
+        "COUNT",
+        "CREATE",
+        "CROSS",
+        "CURRENT",
+        "CURRENT_DATE",
+        "CURRENT_TIME",
+        "CURRENT_TIMESTAMP",
+        "CURRENT_USER",
+        "CURSOR",
+        "DATABASE",
+        "DATE",
+        "DBCC",
+        "DEALLOCATE",
+        "DEC",
+        "DECIMAL",
+        "DECLARE",
+        "DEFAULT",
+        "DEFERRABLE",
+        "DEFERRED",
+        "DELETE",
+        "DENY",
+        "DESC",
+        "DESCRIBE",
+        "DESCRIPTOR",
+        "DIAGNOSTICS",
+        "DISCONNECT",
+        "DISK",
+        "DISTINCT",
+        "DISTRIBUTED",
+        "DOMAIN",
+        "DOUBLE",
+        "DROP",
+        "DUMP",
+        "ELSE",
+        "END",
+        "ERRLVL",
+        "ESCAPE",
+        "EXCEPT",
+        "EXCEPTION",
+        "EXEC",
+        "EXECUTE",
+        "EXISTS",
+        "EXIT",
+        "EXTERNAL",
+        "EXTRACT",
+        "FETCH",
+        "FILE",
+        "FILLFACTOR",
+        "FLOAT",
+        "FOR",
+        "FOREIGN",
+        "FORTRAN",
+        "FOUND",
+        "FREETEXT",
+        "FREETEXTTABLE",
+        "FROM",
+        "FULL",
+        "FUNCTION",
+        "GET",
+        "GLOBAL",
+        "GO",
+        "GOTO",
+        "GRANT",
+        "GROUP",
+        "HAVING",
+        "HOLDLOCK",
+        "HOUR",
+        "IDENTITY",
+        "IDENTITYCOL",
+        "IDENTITY_INSERT",
+        "IF",
+        "IMMEDIATE",
+        "IN",
+        "INCLUDE",
+        "INDEX",
+        "INDICATOR",
+        "INITIALLY",
+        "INNER",
+        "INPUT",
+        "INSENSITIVE",
+        "INSERT",
+        "INT",
+        "INTEGER",
+        "INTERSECT",
+        "INTERVAL",
+        "INTO",
+        "IS",
+        "ISOLATION",
+        "JOIN",
+        "KEY",
+        "KILL",
+        "LANGUAGE",
+        "LAST",
+        "LEADING",
+        "LEFT",
+        "LEVEL",
+        "LIKE",
+        "LINENO",
+        "LOAD",
+        "LOCAL",
+        "LOWER",
+        "MATCH",
+        "MAX",
+        "MERGE",
+        "MIN",
+        "MINUTE",
+        "MODULE",
+        "MONTH",
+        "NAMES",
+        "NATIONAL",
+        "NATURAL",
+        "NCHAR",
+        "NEXT",
+        "NO",
+        "NOCHECK",
+        "NONCLUSTERED",
+        "NONE",
+        "NOT",
+        "NULL",
+        "NULLIF",
+        "NUMERIC",
+        "OCTET_LENGTH",
+        "OF",
+        "OFF",
+        "OFFSETS",
+        "ON",
+        "ONLY",
+        "OPEN",
+        "OPENDATASOURCE",
+        "OPENQUERY",
+        "OPENROWSET",
+        "OPENXML",
+        "OPTION",
+        "OR",
+        "ORDER",
+        "OUTER",
+        "OUTPUT",
+        "OVER",
+        "OVERLAPS",
+        "PAD",
+        "PARTIAL",
+        "PASCAL",
+        "PERCENT",
+        "PIVOT",
+        "PLAN",
+        "POSITION",
+        "PRECISION",
+        "PREPARE",
+        "PRESERVE",
+        "PRIMARY",
+        "PRINT",
+        "PRIOR",
+        "PRIVILEGES",
+        "PROC",
+        "PROCEDURE",
+        "PUBLIC",
+        "RAISERROR",
+        "READ",
+        "READTEXT",
+        "REAL",
+        "RECONFIGURE",
+        "REFERENCES",
+        "RELATIVE",
+        "REPLICATION",
+        "RESTORE",
+        "RESTRICT",
+        "RETURN",
+        "REVERT",
+        "REVOKE",
+        "RIGHT",
+        "ROLLBACK",
+        "ROWCOUNT",
+        "ROWGUIDCOL",
+        "ROWS",
+        "RULE",
+        "SAVE",
+        "SCHEMA",
+        "SCROLL",
+        "SECOND",
+        "SECTION",
+        "SECURITYAUDIT",
+        "SELECT",
+        "SEMANTICKEYPHRASETABLE",
+        "SEMANTICSIMILARITYDETAILSTABLE",
+        "SEMANTICSIMILARITYTABLE",
+        "SESSION",
+        "SESSION_USER",
+        "SET",
+        "SETUSER",
+        "SHUTDOWN",
+        "SIZE",
+        "SMALLINT",
+        "SOME",
+        "SPACE",
+        "SQL",
+        "SQLCA",
+        "SQLCODE",
+        "SQLERROR",
+        "SQLSTATE",
+        "SQLWARNING",
+        "STATISTICS",
+        "SUBSTRING",
+        "SUM",
+        "SYSTEM_USER",
+        "TABLE",
+        "TABLESAMPLE",
+        "TEMPORARY",
+        "TEXTSIZE",
+        "THEN",
+        "TIME",
+        "TIMESTAMP",
+        "TIMEZONE_HOUR",
+        "TIMEZONE_MINUTE",
+        "TO",
+        "TOP",
+        "TRAILING",
+        "TRAN",
+        "TRANSACTION",
+        "TRANSLATE",
+        "TRANSLATION",
+        "TRIGGER",
+        "TRIM",
+        "TRUE",
+        "TRUNCATE",
+        "TRY_CONVERT",
+        "TSEQUAL",
+        "UNION",
+        "UNIQUE",
+        "UNKNOWN",
+        "UNPIVOT",
+        "UPDATE",
+        "UPDATETEXT",
+        "UPPER",
+        "USAGE",
+        "USE",
+        "USER",
+        "USING",
+        "VALUE",
+        "VALUES",
+        "VARCHAR",
+        "VARYING",
+        "VIEW",
+        "WAITFOR",
+        "WHEN",
+        "WHENEVER",
+        "WHERE",
+        "WHILE",
+        "WITH",
+        "WITHIN GROUP",
+        "WORK",
+        "WRITE",
+        "WRITETEXT",
+        "YEAR",
+        "ZONE",
+    ];
+
+    // Cheap upper-case comparison without allocation for ASCII identifiers.
+    if name.is_empty() || name.len() > 32 {
+        return false;
+    }
+    let mut buf = [0u8; 32];
+    for (i, b) in name.as_bytes().iter().enumerate() {
+        buf[i] = b.to_ascii_uppercase();
+    }
+    let upper = match std::str::from_utf8(&buf[..name.len()]) {
+        Ok(s) => s,
+        Err(_) => return false,
+    };
+    RESERVED.binary_search(&upper).is_ok()
+}
+
 /// Dialects that natively support ILIKE.
 pub(crate) fn supports_ilike_builtin(d: Dialect) -> bool {
     matches!(

src/dialects/plugin.rs

@@ -294,6 +294,7 @@ fn typed_function_canonical_name(func: &TypedFunction) -> &'static str {
         TypedFunction::DateTrunc { .. } => "DATE_TRUNC",
         TypedFunction::DateSub { .. } => "DATE_SUB",
         TypedFunction::CurrentDate => "CURRENT_DATE",
+        TypedFunction::CurrentTime => "CURRENT_TIME",
         TypedFunction::CurrentTimestamp => "NOW",
         TypedFunction::StrToTime { .. } => "STR_TO_TIME",
         TypedFunction::TimeToStr { .. } => "TIME_TO_STR",
@@ -368,7 +369,9 @@ fn typed_function_canonical_name(func: &TypedFunction) -> &'static str {
 /// Extract the argument expressions from a TypedFunction (in positional order).
 fn typed_function_args(func: &TypedFunction) -> Vec<Expr> {
     match func {
-        TypedFunction::CurrentDate | TypedFunction::CurrentTimestamp => vec![],
+        TypedFunction::CurrentDate
+        | TypedFunction::CurrentTime
+        | TypedFunction::CurrentTimestamp => vec![],
         TypedFunction::RowNumber | TypedFunction::Rank | TypedFunction::DenseRank => vec![],
         TypedFunction::Length { expr }
         | TypedFunction::Upper { expr }