fix JuliaLang#43960, evaluation order of splat inside ref (JuliaLang#…

…44024)

src/julia-syntax.scm

@@ -130,31 +130,29 @@
 ;; returns (values index-list stmts) where stmts are statements that need
 ;; to execute first.
 (define (process-indices a i)
- (let loop ((lst i)
- (n 1)
- (stmts '())
- (tuples '())
- (ret '()))
- (if (null? lst)
- (values (reverse ret) (reverse stmts))
- (let ((idx (car lst))
- (last (null? (cdr lst))))
- (if (and (pair? idx) (eq? (car idx) '...))
- (if (symbol-like? (cadr idx))
- (loop (cdr lst) (+ n 1)
- stmts
- (cons (cadr idx) tuples)
- (cons `(... ,(replace-beginend (cadr idx) a n tuples last))
- ret))
- (let ((g (make-ssavalue)))
- (loop (cdr lst) (+ n 1)
- (cons `(= ,g ,(replace-beginend (cadr idx) a n tuples last))
- stmts)
- (cons g tuples)
- (cons `(... ,g) ret))))
- (loop (cdr lst) (+ n 1)
- stmts tuples
- (cons (replace-beginend idx a n tuples last) ret)))))))
+ (let ((has-va? (any vararg? i)))
+ (let loop ((lst i)
+ (n 1)
+ (stmts '())
+ (tuples '())
+ (ret '()))
+ (if (null? lst)
+ (values (reverse ret) (reverse stmts))
+ (let* ((idx0 (car lst))
+ (idx (if (vararg? idx0) (cadr idx0) idx0))
+ (last (null? (cdr lst)))
+ (replaced (replace-beginend idx a n tuples last))
+ (idx (if (or (not has-va?) (simple-atom? replaced)) replaced (make-ssavalue))))
+ (loop (cdr lst) (+ n 1)
+ (if (eq? idx replaced)
+ stmts
+ (cons `(= ,idx ,replaced)
+ stmts))
+ (if (vararg? idx0) (cons idx tuples) tuples)
+ (cons (if (vararg? idx0)
+ `(... ,idx)
+ idx)
+ ret)))))))
 
 ;; GF method does not need to keep decl expressions on lambda args
 ;; except for rest arg

test/syntax.jl

@@ -1204,6 +1204,14 @@ end
 @test [(0,0)... 1] == [0 0 1]
 @test Float32[(0,0)... 1] == Float32[0 0 1]
 
+# issue #43960, evaluation order of splatting in `ref`
+let a = [], b = [4,3,2,1]
+ f() = (push!(a, 1); 2)
+ g() = (push!(a, 2); ())
+ @test b[f(), g()...] == 3
+ @test a == [1,2]
+end
+
 @testset "raw_str macro" begin
  @test raw"$" == "\$"
  @test raw"\n" == "\\n"