Support more forms of at-nospecialize.

src/Compat.jl

@@ -7,11 +7,25 @@ using Base.Meta
 @static if !isdefined(Base, Symbol("@nospecialize"))
     # 0.7
     macro nospecialize(arg)
-        earg = esc(arg)
         if isa(arg, Symbol)
-            return :($earg::ANY)
+            # @nospecialize(arg)
+            return :($(esc(arg))::ANY)
+        elseif isa(arg, Expr) && arg.head == :(::)
+            # @nospecialize(arg::typ)
+            # unsupported: needs ::ANY which would change dispatch as determined by ::typ
+        elseif isa(arg, Expr) && arg.head == :(=)
+            # @nospecialize(arg=val)
+            arg, val = arg.args
+            if isa(arg, Expr) && arg.head == :(::)
+                # @nospecialize(arg::typ=val)
+                # unsupported (see above), but generate a kw arg
+                arg, typ = arg.args
+                return Expr(:kw, :($(esc(arg))::$(esc(typ))), esc(val))
+            else
+                return Expr(:kw, :($(esc(arg))::ANY), esc(val))
+            end
         end
-        return earg
+        return esc(arg)
     end
     export @nospecialize
 end

test/runtests.jl

@@ -763,6 +763,16 @@ no_specialize(@nospecialize(x)) = sin(1)
 no_specialize(@nospecialize(x::Integer)) = sin(2)
 @test no_specialize(1.0) == sin(1)
 @test no_specialize(1) == sin(2)
+no_specialize_kw1(@nospecialize(x=0)) = sin(1)
+no_specialize_kw1(@nospecialize(x::Integer)) = sin(2)
+@test no_specialize_kw1(1.0) == sin(1)
+@test no_specialize_kw1(1) == sin(2)
+@test no_specialize_kw1() == sin(2)
+no_specialize_kw2(@nospecialize(x)) = sin(1)
+no_specialize_kw2(@nospecialize(x::Integer=0)) = sin(2)
+@test no_specialize_kw2(1.0) == sin(1)
+@test no_specialize_kw2(1) == sin(2)
+@test no_specialize_kw2() == sin(2)
 
 # 0.7
 @test read(IOBuffer("aaaa"), String) == "aaaa"