Merge pull request #11801 from JuliaLang/jb/globalscopefixes

fix scope issues #7234 and #10472

Author: JeffBezanson

NEWS.md

@@ -35,9 +35,6 @@ New language features
 Language changes
 ----------------
 
-  * Unsigned `BigInt` literal syntax has been removed ([#11105]).
-    Unsigned literals larger than `UInt128` now throw a syntax error.
-
   * Tuple types are now written as `Tuple{A, B}` instead of as `(A, B)`.
     Tuples of bits types are inlined into structs and arrays, like other
     immutable types.
@@ -78,18 +75,21 @@ Language changes
   * `[x,y]` constructs a vector of `x` and `y` instead of concatenating them
     ([#3737], [#2488], [#8599]).
 
+  * Unsigned `BigInt` literal syntax has been removed ([#11105]).
+    Unsigned literals larger than `UInt128` now throw a syntax error.
+
   * `error(::Exception)` and `error(::Type{Exception})` have been deprecated
      in favor of using an explicit `throw` ([#9690]).
 
   * `Uint` etcetera are renamed to `UInt` ([#8905]).
 
   * `String` is renamed to `AbstractString` ([#8872]).
 
-  * `None` is deprecated; use `Union()` instead ([#8423]).
+  * `None` is deprecated; use `Union{}` instead ([#8423]).
 
   * `Nothing` (the type of `nothing`) is renamed to `Void` ([#8423]).
 
-  * Arrays can be constructed with the syntax `Array{T}(m,n)` ([#3214], [#10075])
+  * Arrays can be constructed with the syntax `Array{T}(m,n)` ([#3214], [#10075]).
 
   * `Dict` literal syntax `[a=>b,c=>d]` is replaced by `Dict(a=>b,c=>d)`,
     `{a=>b}` is replaced by `Dict{Any,Any}(a=>b)`, and
@@ -122,6 +122,9 @@ Language changes
   * Unions of types should now be written with curly braces instead of parentheses, i.e.
     `Union{Type1, Type2}` instead of `Union(Type1, Type2)` ([#11432]).
 
+  * The keyword `local` is no longer allowed in global scope. Use `let` instead of
+    `begin` to create a new scope from the top level ([#7234], [#10472]).
+
 Command line option changes
 ---------------------------
 

base/broadcast.jl

@@ -185,7 +185,7 @@ end
 function gen_broadcast_function(genbody::Function, nd::Int, narrays::Int, f::Function)
     As = [symbol("A_"*string(i)) for i = 1:narrays]
     body = genbody(nd, narrays, f)
-    @eval begin
+    @eval let
         local _F_
         function _F_(B, $(As...))
             $body
@@ -197,7 +197,7 @@ end
 function gen_broadcast_function_tobitarray(genbody::Function, nd::Int, narrays::Int, f::Function)
     As = [symbol("A_"*string(i)) for i = 1:narrays]
     body = genbody(nd, narrays, f)
-    @eval begin
+    @eval let
         local _F_
         function _F_(B::BitArray, $(As...))
             $body

base/printf.jl

@@ -1041,7 +1041,7 @@ function _printf(macroname, io, fmt, args)
     end
 
     unshift!(blk.args, :(out = $io))
-    blk
+    Expr(:let, blk)
 end
 
 macro printf(args...)
@@ -1059,9 +1059,9 @@ macro sprintf(args...)
     !isempty(args) || throw(ArgumentError("@sprintf: called with zero arguments"))
     isa(args[1], AbstractString) || is_str_expr(args[1]) ||
         throw(ArgumentError("@sprintf: first argument must be a format string"))
-    blk = _printf("@sprintf", :(IOBuffer()), args[1], args[2:end])
-    push!(blk.args, :(takebuf_string(out)))
-    blk
+    letexpr = _printf("@sprintf", :(IOBuffer()), args[1], args[2:end])
+    push!(letexpr.args[1].args, :(takebuf_string(out)))
+    letexpr
 end
 
 end # module

base/sparse/sparsematrix.jl

@@ -756,7 +756,7 @@ end
 
 function gen_broadcast_function_sparse(genbody::Function, f::Function, is_first_sparse::Bool)
     body = genbody(f, is_first_sparse)
-    @eval begin
+    @eval let
         local _F_
         function _F_{Tv,Ti}(B::SparseMatrixCSC{Tv,Ti}, A_1, A_2)
             $body

base/sysimg.jl

@@ -149,9 +149,8 @@ include("multidimensional.jl")
 
 include("primes.jl")
 
-begin
-    SOURCE_PATH = ""
-    include = function(path)
+let SOURCE_PATH = ""
+    global include = function(path)
         prev = SOURCE_PATH
         path = joinpath(dirname(prev),path)
         SOURCE_PATH = path

doc/manual/variables-and-scoping.rst

@@ -284,16 +284,7 @@ block without creating any new bindings:
 
 .. doctest::
 
-    julia> begin
-             local x = 1
-             begin
-               local x = 2
-             end
-             x
-           end
-    ERROR: syntax: local "x" declared twice
-
-    julia> begin
+    julia> let
              local x = 1
              let
                local x = 2
@@ -302,9 +293,7 @@ block without creating any new bindings:
            end
     1
 
-The first example is invalid because you cannot declare the same
-variable as local in the same scope twice. The second example is valid
-since the ``let`` introduces a new scope block, so the inner local ``x``
+Since ``let`` introduces a new scope block, the inner local ``x``
 is a different variable than the outer local ``x``.
 
 For Loops and Comprehensions

src/jlfrontend.scm

@@ -59,13 +59,16 @@
     (append
      ;; vars assigned at the outer level
      (filter (lambda (x) (not (some-gensym? x))) (find-assigned-vars e '()))
-     ;; vars declared const outside any scope block
-     (find-decls 'const e '())
+     ;; vars declared const or global outside any scope block
+     (find-decls 'const e)
+     (find-decls 'global e)
      ;; vars assigned anywhere, if they have been defined as global
      (filter defined-julia-global (find-possible-globals e))))
    (append
-    (find-decls 'local  e '())
-    (find-decls 'local! e '()))))
+    (if (null? (find-decls 'local e))
+	'()
+	(error "local declaration in global scope"))
+    (find-decls 'local! e))))
 
 ;; return a lambda expression representing a thunk for a top-level expression
 ;; note: expansion of stuff inside module is delayed, so the contents obey
@@ -88,7 +91,7 @@
                       (th (julia-expand1
                            `(lambda ()
                               (scope-block
-                               (block ,@(map (lambda (v) `(global ,v)) gv)
+                               (block ,@(map (lambda (v) `(implicit-global ,v)) gv)
                                       ,ex))))))
                  (if (null? (car (caddr th)))
                      ;; if no locals, return just body of function

src/julia-syntax.scm

@@ -971,19 +971,23 @@
    (sparam-name-bounds params '() '())
    `(block
      (const ,name)
-     ,@(map (lambda (v) `(local ,v)) params)
-     ,@(map make-assignment params (symbols->typevars params bounds #f))
-     (abstract_type ,name (call (top svec) ,@params) ,super))))
+     (scope-block
+      (block
+       ,@(map (lambda (v) `(local ,v)) params)
+       ,@(map make-assignment params (symbols->typevars params bounds #f))
+       (abstract_type ,name (call (top svec) ,@params) ,super))))))
 
 (define (bits-def-expr n name params super)
   (receive
    (params bounds)
    (sparam-name-bounds params '() '())
    `(block
      (const ,name)
-     ,@(map (lambda (v) `(local ,v)) params)
-     ,@(map make-assignment params (symbols->typevars params bounds #f))
-     (bits_type ,name (call (top svec) ,@params) ,n ,super))))
+     (scope-block
+      (block
+       ,@(map (lambda (v) `(local ,v)) params)
+       ,@(map make-assignment params (symbols->typevars params bounds #f))
+       (bits_type ,name (call (top svec) ,@params) ,n ,super))))))
 
 ; take apart a type signature, e.g. T{X} <: S{Y}
 (define (analyze-type-sig ex)
@@ -2569,15 +2573,6 @@ The first one gave something broken, but the second case works.
 So far only the second case can actually occur.
 |#
 
-(define (declared-global-vars e)
-  (if (or (not (pair? e)) (quoted? e))
-      '()
-      (case (car e)
-        ((lambda scope-block)  '())
-        ((global)  (cdr e))
-        (else
-         (apply append (map declared-global-vars e))))))
-
 (define (check-dups locals)
   (if (and (pair? locals) (pair? (cdr locals)))
       (or (and (memq (car locals) (cdr locals))
@@ -2604,26 +2599,27 @@ So far only the second case can actually occur.
          (apply append! (map (lambda (x) (find-assigned-vars x env))
                              e))))))
 
-(define (find-decls kind e env)
+(define (find-decls kind e)
   (if (or (not (pair? e)) (quoted? e))
       '()
       (cond ((or (eq? (car e) 'lambda) (eq? (car e) 'scope-block))
              '())
             ((eq? (car e) kind)
              (list (decl-var (cadr e))))
             (else
-             (apply append! (map (lambda (x) (find-decls kind x env))
+             (apply append! (map (lambda (x) (find-decls kind x))
                                  e))))))
 
-(define (find-local-decls  e env) (find-decls 'local  e env))
-(define (find-local!-decls e env) (find-decls 'local! e env))
+(define (find-local-decls  e) (find-decls 'local  e))
+(define (find-local!-decls e) (find-decls 'local! e))
+(define (find-global-decls e) (find-decls 'global e))
 
 (define (find-locals e env glob)
   (delete-duplicates
-   (append! (check-dups (find-local-decls e env))
+   (append! (check-dups (find-local-decls e))
             ;; const decls on non-globals also introduce locals
-            (diff (find-decls 'const e env) glob)
-            (find-local!-decls e env)
+            (diff (find-decls 'const e) glob)
+            (find-local!-decls e)
             (find-assigned-vars e env))))
 
 (define (remove-local-decls e)
@@ -2643,22 +2639,30 @@ So far only the second case can actually occur.
 ;; 2. (const x) expressions in a scope-block where x is not declared global
 ;; 3. variables assigned inside this scope-block that don't exist in outer
 ;;    scopes
-(define (add-local-decls e env)
+(define (add-local-decls e env implicitglobals)
   (if (or (not (pair? e)) (quoted? e)) e
       (cond ((eq? (car e) 'lambda)
              (let* ((env (append (lam:vars e) env))
-                    (body (add-local-decls (caddr e) env)))
+                    (body (add-local-decls (caddr e) env
+					   ;; don't propagate implicit globals
+					   ;; issue #7234
+					   '())))
                (list 'lambda (cadr e) body)))
 
             ((eq? (car e) 'scope-block)
-             (let* ((glob (declared-global-vars (cadr e)))
+             (let* ((iglo (find-decls 'implicit-global (cadr e)))
+		    (glob (diff (find-global-decls (cadr e)) iglo))
                     (vars (find-locals
                            ;; being declared global prevents a variable
                            ;; assignment from introducing a local
-                           (cadr e) (append env glob) glob))
-                    (body (add-local-decls (cadr e) (append vars glob env)))
-                    (lineno (if (and (length> body 1)
-                                     (pair? (cadr body))
+                           (cadr e)
+			   (append env glob implicitglobals iglo)
+			   (append glob iglo)))
+                    (body (add-local-decls (cadr e)
+					   (append vars glob env)
+					   (append iglo implicitglobals)))
+		    (lineno (if (and (length> body 1)
+				     (pair? (cadr body))
                                      (eq? 'line (car (cadr body))))
                                 (list (cadr body))
                                 '()))
@@ -2678,10 +2682,10 @@ So far only the second case can actually occur.
              ;; form (local! x) adds a local to a normal (non-scope) block
              (let ((newenv (append (declared-local!-vars e) env)))
                (map (lambda (x)
-                      (add-local-decls x newenv))
+                      (add-local-decls x newenv implicitglobals))
                     e))))))
 
-(define (identify-locals e) (add-local-decls e '()))
+(define (identify-locals e) (add-local-decls e '() '()))
 
 (define (declared-local-vars e)
   (map (lambda (x) (decl-var (cadr x)))
@@ -2719,10 +2723,10 @@ So far only the second case can actually occur.
                          (case (car e)
                            ((lambda)
                             (append (lambda-all-vars e)
-                                    (declared-global-vars (cadddr e))))
+                                    (find-global-decls (cadddr e))))
                            ((scope-block)
                             (append (declared-local-vars e)
-                                    (declared-global-vars (cadr e))))
+                                    (find-global-decls (cadr e))))
                            (else '())))))
            (cons (car e)
                  (map (lambda (x)
@@ -2959,7 +2963,7 @@ So far only the second case can actually occur.
                                                        (if vi (free-vars (vinfo:type vi)) '())))
                                                    fv))))
                         (append (diff dv fv) fv)))
-                (glo  (declared-global-vars (lam:body e)))
+                (glo  (find-global-decls (lam:body e)))
                 ;; make var-info records for vars introduced by this lambda
                 (vi   (nconc
                        (map (lambda (decl) (make-var-info (decl-var decl)))
@@ -3194,6 +3198,7 @@ So far only the second case can actually occur.
                ))
 
             ((global) #f)  ; remove global declarations
+            ((implicit-global) #f)
             ((local!) #f)
             ((jlgensym) #f)
             ((local)

test/arrayops.jl

@@ -383,7 +383,7 @@ for i = 1 : 3
     @test isequal(a', permutedims(a, [2, 1]))
 end
 
-begin
+let
     local A, A1, A2, A3, v, v2, cv, cv2, c, R, T
     A = ones(Int,2,3,4)
     A1 = reshape(repmat([1,2],1,12),2,3,4)
@@ -642,7 +642,7 @@ B = cat(3, 1, 2, 3)
 @test isequal(symdiff(Int64[]), Int64[])
 
 # mapslices
-begin
+let
     local a,h,i
     a = rand(5,5)
     h = mapslices(v -> hist(v,0:0.1:1)[2], a, 1)
@@ -725,7 +725,7 @@ a[a] = [4,5,6]
 @test lexcmp([1, 1], [1]) == 1
 
 # sort on arrays
-begin
+let
     local a = rand(3,3)
 
     asr = sortrows(a)