add strict position tracking, prevent equals operator in DECLARE assignments

Author: emrberk

src/parser/lexer.ts

@@ -869,7 +869,7 @@ export const allTokens: TokenType[] = [
 // Lexer Instance
 // =============================================================================
 
-export const QuestDBLexer = new Lexer(allTokens)
+export const QuestDBLexer = new Lexer(allTokens, { positionTracking: "full" })
 
 export function tokenize(input: string) {
   const result = QuestDBLexer.tokenize(input)

src/parser/parser.ts

@@ -1403,10 +1403,7 @@ class QuestDBParser extends CstParser {
   private declareAssignment = this.RULE("declareAssignment", () => {
     this.OPTION(() => this.CONSUME(Overridable))
     this.CONSUME(VariableReference)
-    this.OR([
-      { ALT: () => this.CONSUME(ColonEquals) },
-      { ALT: () => this.CONSUME(Equals) },
-    ])
+    this.CONSUME(ColonEquals)
     this.SUBRULE(this.expression)
   })
 

tests/parser.test.ts

@@ -4720,16 +4720,11 @@ orders PIVOT (sum(amount) FOR status IN ('open'))`
 
     // --- Fix 8-10: DECLARE, PARTITION BY WEEK ---
 
-    it("should parse DECLARE with variable assignment using equals", () => {
+    it("should REJECT DECLARE assignments using `=` (server requires `:=`)", () => {
       const result = parseToAst(
         "DECLARE @cutoff = '2024-01-01' SELECT * FROM t WHERE ts < @cutoff",
       )
-      expect(result.errors).toHaveLength(0)
-      const stmt = result.ast[0] as AST.SelectStatement
-      expect(stmt.type).toBe("select")
-      expect(stmt.declare).toBeDefined()
-      expect(stmt.declare?.assignments).toHaveLength(1)
-      expect(stmt.declare?.assignments[0].name).toBe("cutoff")
+      expect(result.errors.length).toBeGreaterThan(0)
     })
 
     it("should parse CREATE MATERIALIZED VIEW with PARTITION BY WEEK", () => {