fix #23996, bug in local function capturing in lambda-optimize-vars (#24004)

Author: JeffBezanson

src/julia-syntax.scm

@@ -3059,14 +3059,29 @@ f(x) = yt(x)
     (take body)
     (reverse! acc)))
 
+;; find all methods for the same function as `ex` in `body`
+(define (all-methods-for ex body)
+  (let ((mname (method-expr-name ex)))
+    (expr-find-all (lambda (s)
+                     (and (length> s 2) (eq? (car s) 'method)
+                          (eq? (method-expr-name s) mname)))
+                   body
+                   identity
+                   (lambda (x) (and (pair? x) (not (eq? (car x) 'lambda)))))))
+
 ;; clear capture bit for vars assigned once at the top, to avoid allocating
 ;; some unnecessary Boxes.
 (define (lambda-optimize-vars! lam)
-  (define (expr-uses-var ex v)
+  (define (expr-uses-var ex v stmts)
     (cond ((assignment? ex) (expr-contains-eq v (caddr ex)))
           ((eq? (car ex) 'method)
            (and (length> ex 2)
-                (assq v (cadr (lam:vinfo (cadddr ex))))))
+                ;; a method expression captures a variable if any methods for the
+                ;; same function do.
+                (let ((all-methods (all-methods-for ex (cons 'body stmts))))
+                  (any (lambda (ex)
+                         (assq v (cadr (lam:vinfo (cadddr ex)))))
+                       all-methods))))
           (else (expr-contains-eq v ex))))
   (assert (eq? (car lam) 'lambda))
   (let ((vi (car (lam:vinfo lam))))
@@ -3092,7 +3107,7 @@ f(x) = yt(x)
           ;; TODO: reorder leading statements to put assignments where the RHS is
           ;; `simple-atom?` at the top.
           (for-each (lambda (e)
-                      (set! unused (filter (lambda (v) (not (expr-uses-var e v)))
+                      (set! unused (filter (lambda (v) (not (expr-uses-var e v leading)))
                                            unused))
                       (if (and (memq (car e) '(method =)) (memq (cadr e) unused))
                           (let ((v (assq (cadr e) vi)))
@@ -3273,9 +3288,8 @@ f(x) = yt(x)
                                         (and name
                                              (symbol (string "#" name "#" (current-julia-module-counter))))))
                         (alldefs (expr-find-all
-                                  (lambda (ex) (and (eq? (car ex) 'method)
+                                  (lambda (ex) (and (length> ex 2) (eq? (car ex) 'method)
                                                     (not (eq? ex e))
-                                                    (length> ex 2)
                                                     (eq? (method-expr-name ex) name)))
                                   (lam:body lam)
                                   identity

test/core.jl

@@ -335,6 +335,20 @@ c23558(n,k) =
     end
 @test c23558(10, 5) == 252
 
+# issue #23996
+function foo23996(xs...)
+    rets = []
+    bar(::Int) = push!(rets, 1)
+    foobar() = push!(rets, 3)
+    bar(::AbstractFloat) = push!(rets, 2)
+    bar(::Bool) = foobar()
+    for x in xs
+	bar(x)
+    end
+    rets
+end
+@test foo23996(1,2.0,false) == [1,2,3]
+
 # variable scope, globals
 glob_x = 23
 function glotest()