Fix @nospecialize with zero args (#112)

Author: mlechu

src/compat.jl

@@ -80,7 +80,7 @@ end
 
 """
 Return `e.args`, but with any parameters in SyntaxTree (flattened, source) order.
-Parameters are expected to be as `e.args[pos]`.
+Parameters are expected to be at `e.args[pos]`.
 
 e.g. orderings of (a,b,c;d;e;f):
   Expr:       (tuple (parameters (parameters (parameters f) e) d) a b c)
@@ -463,36 +463,35 @@ function _insert_convert_expr(@nospecialize(e), graph::SyntaxGraph, src::SourceA
         if e.args[1] isa Expr && e.args[1].head === :purity
             st_k = K"meta"
             child_exprs = [Expr(:quoted_symbol, :purity), Base.EffectsOverride(e.args[1].args...)]
-        else
-            @assert e.args[1] isa Symbol
-            if e.args[1] === :nospecialize
-                if nargs > 2
-                    st_k = K"block"
-                    # Kick the can down the road (should only be simple atoms?)
-                    child_exprs = map(c->Expr(:meta, :nospecialize, c), child_exprs[2:end])
-                else
-                    st_id, src = _insert_convert_expr(e.args[2], graph, src)
-                    setmeta!(SyntaxTree(graph, st_id); nospecialize=true)
-                    return st_id, src
-                end
-            elseif e.args[1] in (:inline, :noinline, :generated, :generated_only,
-                                 :max_methods, :optlevel, :toplevel, :push_loc, :pop_loc,
-                                 :no_constprop, :aggressive_constprop, :specialize, :compile, :infer,
-                                 :nospecializeinfer, :force_compile, :propagate_inbounds, :doc)
-                # TODO: Some need to be handled in lowering
-                for (i, ma) in enumerate(e.args)
-                    if ma isa Symbol
-                        # @propagate_inbounds becomes (meta inline
-                        # propagate_inbounds), but usually(?) only args[1] is
-                        # converted here
-                        child_exprs[i] = Expr(:quoted_symbol, e.args[i])
-                    end
+        elseif nargs === 0
+            # pass
+        elseif e.args[1] === :nospecialize
+            if nargs === 1
+                child_exprs[1] = Expr(:quoted_symbol, :nospecialize)
+            elseif nargs > 2
+                st_k = K"block"
+                # Kick the can down the road (should only be simple atoms?)
+                child_exprs = map(c->Expr(:meta, :nospecialize, c), child_exprs[2:end])
+            elseif nargs === 2
+                st_id, src = _insert_convert_expr(e.args[2], graph, src)
+                setmeta!(SyntaxTree(graph, st_id); nospecialize=true)
+                return st_id, src
+            end
+        elseif e.args[1] in (:inline, :noinline, :generated, :generated_only,
+                             :max_methods, :optlevel, :toplevel, :push_loc, :pop_loc,
+                             :no_constprop, :aggressive_constprop, :specialize, :compile, :infer,
+                             :nospecializeinfer, :force_compile, :propagate_inbounds, :doc)
+            # TODO: Some need to be handled in lowering
+            for (i, ma) in enumerate(e.args)
+                if ma isa Symbol
+                    # @propagate_inbounds becomes (meta inline propagate_inbounds)
+                    child_exprs[i] = Expr(:quoted_symbol, e.args[i])
                 end
-            else
-                # Can't throw a hard error; it is explicitly tested that meta can take arbitrary keys.
-                @error("Unknown meta form at $src: `$e`\n$(sprint(dump, e))")
-                child_exprs[1] = Expr(:quoted_symbol, e.args[1])
             end
+        else
+            # Can't throw a hard error; it is explicitly tested that meta can take arbitrary keys.
+            @error("Unknown meta form at $src: `$e`\n$(sprint(dump, e))")
+            child_exprs[1] = Expr(:quoted_symbol, e.args[1])
         end
     elseif e.head === :scope_layer
         @assert nargs === 2

test/macros_ir.jl

@@ -186,3 +186,25 @@ cmdmac`hello`
 cmdmac`hello`12345
 #---------------------
 1   (return "hello from cmdmac with suffix 12345")
+
+########################################
+# @nospecialize (zero args)
+function foo()
+    @nospecialize
+end
+#---------------------
+1   (method TestMod.foo)
+2   latestworld
+3   TestMod.foo
+4   (call core.Typeof %₃)
+5   (call core.svec %₄)
+6   (call core.svec)
+7   SourceLocation::1:10
+8   (call core.svec %₅ %₆ %₇)
+9   --- method core.nothing %₈
+    slots: [slot₁/#self#(!read)]
+    1   (meta :nospecialize)
+    2   (return core.nothing)
+10  latestworld
+11  TestMod.foo
+12  (return %₁₁)

test/utils.jl

@@ -114,7 +114,10 @@ function uncomment_description(desc)
 end
 
 function comment_description(desc)
-    replace(desc, r"^"m=>"# ")
+    lines = replace(split(desc, '\n')) do line
+        strip("# " * line)
+    end
+    join(lines, '\n')
 end
 
 function match_ir_test_case(case_str)
@@ -231,7 +234,7 @@ function refresh_ir_test_cases(filename, pattern=nothing)
         else
             ir = case.output
         end
-        println(io,
+        (case == cases[end] ? print : println)(io,
             """
             ########################################
             $(comment_description(case.description))