Fix handling of kwargs in @polynomial_ring (Nemocas#1632)

src/misc/VarNames.jl

@@ -290,8 +290,12 @@ function varnames_macro(f, args_count, opt_in)
             # Keyword arguments after `;` end up in `kv`.
             # Those without previous `;` get evaluated and end up in `kv2`.
             # Note: one could work around evaluating the latter if necessary.
-            kv = Meta.isexpr(first(args), :parameters) ?
-                popfirst!(args).args : Expr(:parameters)
+            if Meta.isexpr(first(args), :parameters)
+                kv = first(args)
+                args = args[2:end]
+            else
+                kv = Expr(:parameters)
+            end
 
             req(length(args) >= $args_count+1, "Not enough arguments")
             base_args = args[1:$args_count]

test/generic/MPoly-test.jl

@@ -140,6 +140,17 @@
    QQxxx3 = @polynomial_ring(QQ, :x=>1:3)
    @test QQxxx_ == (QQxxx3, [x1, x2, x3])
 
+   # test support of kwargs
+   QQxxx4 = @polynomial_ring(QQ, "x#" => 1:3; internal_ordering=:lex)
+   @test QQxxx_ == (QQxxx4, [x1, x2, x3])
+
+   QQxxx_deglex_ = @inferred polynomial_ring(QQ, "x#" => 1:3; internal_ordering=:deglex)
+   @test internal_ordering(QQxxx_deglex_[1]) == :deglex
+
+   QQxxx_deglex2 = @polynomial_ring(QQ, "x#" => 1:3; internal_ordering=:deglex)
+   @test internal_ordering(QQxxx_deglex2) == :deglex
+   @test QQxxx_deglex_ == (QQxxx_deglex2, [x1, x2, x3])
+
    ZZxy_ = @inferred polynomial_ring(ZZ, :x => (1:2, 1:2), :y => 0:3)
 
    ZZxy2_ = @inferred polynomial_ring(ZZ, :x => ["1, 1" "1, 2"; "2, 1" "2, 2"], :y => (0:3,))