lowering: fix lhs-decls not handling parameters (#47274)

This caused const to be dropped from declarations involving named
tuple destructuring.

Fixes #47168

Author: apaz-cli

src/julia-syntax.scm

@@ -2910,18 +2910,17 @@
          ,(construct-loops (reverse itrs) (reverse iv))
          ,result)))))
 
-(define (lhs-vars e)
-  (cond ((symdecl? e)   (list (decl-var e)))
-        ((and (pair? e) (eq? (car e) 'tuple))
-         (apply append (map lhs-vars (cdr e))))
-        (else '())))
-
 (define (lhs-decls e)
   (cond ((symdecl? e)   (list e))
-        ((and (pair? e) (eq? (car e) 'tuple))
+        ((and (pair? e)
+              (or (eq? (car e) 'tuple)
+                  (eq? (car e) 'parameters)))
          (apply append (map lhs-decls (cdr e))))
         (else '())))
 
+(define (lhs-vars e)
+  (map decl-var (lhs-decls e)))
+
 (define (all-decl-vars e)  ;; map decl-var over every level of an assignment LHS
   (cond ((eventually-call? e) e)
         ((decl? e)   (decl-var e))

test/syntax.jl

@@ -848,6 +848,14 @@ end
 @test c8925 == 3 && isconst(@__MODULE__, :c8925)
 @test d8925 == 4 && isconst(@__MODULE__, :d8925)
 
+# issue #47168
+let t47168 = (;a47168 = 1, b47168 = 2);
+    global const (;a47168, b47168) = t47168
+    @test a47168 == 1 && isconst(@__MODULE__, :a47168)
+    @test b47168 == 2 && isconst(@__MODULE__, :b47168)
+end
+@test (let x = (;x=1); let (;x) = x; x; end, x; end) == (1, (x = 1,))
+
 # issue #18754: parse ccall as a regular function
 @test Meta.parse("ccall([1], 2)[3]") == Expr(:ref, Expr(:call, :ccall, Expr(:vect, 1), 2), 3)
 @test Meta.parse("ccall(a).member") == Expr(:., Expr(:call, :ccall, :a), QuoteNode(:member))