fix #9474 (missing parens in expr show for ::, :, etc)

Author: stevengj

base/show.jl

@@ -247,6 +247,7 @@ const uni_ops = Set{Symbol}([:(+), :(-), :(!), :(¬), :(~), :(<:), :(>:), :(√)
 const expr_infix_wide = Set([:(=), :(+=), :(-=), :(*=), :(/=), :(\=), :(&=),
     :(|=), :($=), :(>>>=), :(>>=), :(<<=), :(&&), :(||), :(<:), :(=>)])
 const expr_infix = Set([:(:), :(->), symbol("::")])
+const expr_infix_any = union(expr_infix, expr_infix_wide)
 const expr_calls  = Dict(:call =>('(',')'), :calldecl =>('(',')'), :ref =>('[',']'), :curly =>('{','}'))
 const expr_parens = Dict(:tuple=>('(',')'), :vcat=>('[',']'), :cell1d=>("Any[","]"),
                          :hcat =>('[',']'), :row =>('[',']'))
@@ -423,15 +424,13 @@ function show_unquoted(io::IO, ex::Expr, indent::Int, prec::Int)
         end
 
     # infix (i.e. "x<:y" or "x = y")
-    elseif (head in expr_infix && nargs==2) || (is(head,:(:)) && nargs==3)
-        show_list(io, args, head, indent, 0, true)
-
-    elseif head in expr_infix_wide && nargs == 2
+    elseif (head in expr_infix_any && nargs==2) || (is(head,:(:)) && nargs==3)
         func_prec = operator_precedence(head)
+        head_ = head in expr_infix_wide ? " $head " : head
         if func_prec < prec
-            show_enclosed_list(io, '(', args, " $head ", ')', indent, func_prec, true)
+            show_enclosed_list(io, '(', args, head_, ')', indent, func_prec, true)
         else
-            show_list(io, args, " $head ", indent, func_prec, true)
+            show_list(io, args, head_, indent, func_prec, true)
         end
 
     # list (i.e. "(1,2,3)" or "[1,2,3]")

test/show.jl

@@ -191,3 +191,8 @@ end"
 @test_repr "< :: T"
 @test_repr "S{< <: T}"
 @test_repr "+ + +"
+
+# issue #9474
+for s in ("(1::Int64 == 1::Int64)::Bool", "(1:2:3) + 4", "x = 1:2:3")
+    @test sprint(show, parse(s)) == ":("*s*")"
+end