make broadcasting into getproperty extensible

base/Base.jl

@@ -31,6 +31,7 @@ getproperty(x::Tuple, f::Int) = getfield(x, f)
 setproperty!(x::Tuple, f::Int, v) = setfield!(x, f, v) # to get a decent error
 
 getproperty(x, f::Symbol) = getfield(x, f)
+dotgetproperty(x, f) = getproperty(x, f)
 setproperty!(x, f::Symbol, v) = setfield!(x, f, convert(fieldtype(typeof(x), f), v))
 
 include("coreio.jl")

src/julia-syntax.scm

@@ -1545,7 +1545,10 @@
 (define (expand-update-operator- op op= lhs rhs declT)
   (let* ((e      (remove-argument-side-effects lhs))
          (newlhs (car e))
-         (temp   (and (eq? op= '|.=|) (pair? newlhs) (not (eq? (car newlhs) 'ref))
+         (temp   (and (eq? op= '|.=|)
+                      (pair? newlhs)
+                      (not (or (eq? (car newlhs) 'ref)
+                               (and (eq? (car newlhs) '|.|) (length= newlhs 3))))
                       (make-ssavalue)))
          (e      (if temp
                      (cons temp (append (cdr e) (list `(= ,temp ,newlhs))))
@@ -1742,13 +1745,15 @@
          gen))))
 
 (define (ref-to-view expr)
-  (if (and (pair? expr) (eq? (car expr) 'ref))
-      (let* ((ex (partially-expand-ref expr))
-             (stmts (butlast (cdr ex)))
-             (refex (last    (cdr ex)))
-             (nuref `(call (top dotview) ,(caddr refex) ,@(cdddr refex))))
-        `(block ,@stmts ,nuref))
-      expr))
+  (cond ((and (pair? expr) (eq? (car expr) 'ref))
+         (let* ((ex (partially-expand-ref expr))
+                (stmts (butlast (cdr ex)))
+                (refex (last    (cdr ex)))
+                (nuref `(call (top dotview) ,(caddr refex) ,@(cdddr refex))))
+           `(block ,@stmts ,nuref)))
+        ((and (length= expr 3) (eq? (car expr) '|.|))
+         `(call (top dotgetproperty) ,(cadr expr) ,(caddr expr)))
+        (else expr)))
 
 ; lazily fuse nested calls to expr == f.(args...) into a single broadcast call,
 ; or a broadcast! call if lhs is non-null.

test/syntax.jl

@@ -828,7 +828,7 @@ let ε=1, μ=2, x=3, î=4
     @test µ == μ == 2
     # NFC normalization of identifiers:
     @test Meta.parse("\u0069\u0302") === Meta.parse("\u00ee")
-    @test î == 4
+    @test î == 4
     # latin vs greek ε (#14751)
     @test Meta.parse("\u025B") === Meta.parse("\u03B5")
     @test ɛ == ε == 1
@@ -2727,6 +2727,21 @@ end
 @eval f39705(x) = $(Expr(:||)) && x
 @test f39705(1) === false
 
+
+struct A x end
+Base.dotgetproperty(::A, ::Symbol) = [0, 0, 0]
+
+@testset "dotgetproperty" begin
+    a = (x = [1, 2, 3],)
+    @test @inferred((a -> a.x .+= 1)(a)) == [2, 3, 4]
+
+    b = [1, 2, 3]
+    @test A(b).x === b
+    @test begin A(b).x .= 1 end == [1, 1, 1]
+    @test begin A(b).x .+= 1 end == [2, 3, 4]
+    @test b == [1, 2, 3]
+end
+
 @test Meta.@lower((::T) = x) == Expr(:error, "invalid assignment location \"::T\"")
 @test Meta.@lower((::T,) = x) == Expr(:error, "invalid assignment location \"::T\"")
 @test Meta.@lower((; ::T) = x) == Expr(:error, "invalid assignment location \"::T\"")