Ensure the macro system respects imports hygiene, closes #875

Author: José Valim

lib/elixir/include/elixir.hrl

@@ -28,9 +28,9 @@
   aliases,                 %% an orddict with aliases by new -> old names
   file,                    %% the current scope filename
   requires,                %% a set with modules required
-  macro_macros,            %% a list with macros imported from module inside a macro
+  macro_macros=[],         %% a list with macros imported from module inside a macro
   macros,                  %% a list with macros imported from module
-  macro_functions,         %% a list with functions imported from module inside a macro
+  macro_functions=[],      %% a list with functions imported from module inside a macro
   functions                %% a list with functions imported from module
 }).
 

lib/elixir/src/elixir_dispatch.erl

@@ -191,16 +191,24 @@ translate_expansion(Meta, Tree, S) ->
     elixir_quote:linify(?line(Meta), Tree),
     S#elixir_scope{
       check_clauses=false,
-      macro_aliases=[] }
+      macro_functions=[],
+      macro_macros=[],
+      macro_aliases=[]
+    }
   ),
   { TR, TS#elixir_scope{
     check_clauses=S#elixir_scope.check_clauses,
+    macro_functions=merge_imports(S#elixir_scope.macro_functions, TS#elixir_scope.macro_functions),
+    macro_macros=merge_imports(S#elixir_scope.macro_macros, TS#elixir_scope.macro_macros),
     macro_aliases=merge_aliases(S#elixir_scope.macro_aliases, TS#elixir_scope.macro_aliases)
   } }.
 
 merge_aliases(A1, A2) ->
   orddict:merge(fun(_K,_V1,V2) -> V2 end, A1, A2).
 
+merge_imports(A1, A2) ->
+  A2 ++ lists:foldl(fun({ Key, _ }, Acc) -> lists:keydelete(Key, 1, Acc) end, A1, A2).
+
 %% Helpers
 
 skip_require(Meta) ->
@@ -210,7 +218,7 @@ find_dispatch(Meta, Tuple, S) ->
   find_dispatch(Meta, Tuple, [], S).
 
 find_dispatch(Meta, Tuple, Extra, S) ->
-  case lists:keyfind(import, 1, Meta) of
+  case is_import(Meta, Tuple, S) of
     { import, _ } = Import ->
       Import;
     false ->
@@ -235,6 +243,19 @@ find_dispatch(Meta, Tuple, Extra, S) ->
 find_dispatch(Tuple, List) ->
   [Receiver || { Receiver, Set } <- List, is_element(Tuple, Set)].
 
+is_import(Meta, Tuple, S) ->
+  case lists:keyfind(import, 1, Meta) of
+    { import, _ } = Import ->
+      not_an_import(Tuple, S#elixir_scope.macro_functions)
+        andalso not_an_import(Tuple, S#elixir_scope.macro_macros)
+        andalso Import;
+    false ->
+      false
+  end.
+
+not_an_import(Tuple, Pairs) ->
+  not lists:any(fun({ _, List }) -> lists:member(Tuple, List) end, Pairs).
+
 munge_stacktrace(Info, [{ _, _, [S|_], _ }|_], S) ->
   [Info];
 

lib/elixir/src/elixir_import.erl

@@ -41,9 +41,9 @@ import(Meta, Ref, Opts, Selector, S) ->
     false -> S;
     true  ->
       FunctionsFun = fun(K) -> remove_underscored(K andalso Selector, get_functions(Ref)) end,
-      Functions = calculate(Meta, Ref, Opts,
-        S#elixir_scope.functions, FunctionsFun, S),
-      S#elixir_scope{functions=Functions}
+      { Functions, TempF } = calculate(Meta, Ref, Opts,
+        S#elixir_scope.functions, S#elixir_scope.macro_functions, FunctionsFun, S),
+      S#elixir_scope{functions=Functions, macro_functions=TempF}
   end,
 
   SM = case IncludeAll or (Selector == macros) of
@@ -55,9 +55,9 @@ import(Meta, Ref, Opts, Selector, S) ->
           false -> get_macros(Meta, Ref, SF)
         end
       end,
-      Macros = calculate(Meta, Ref, Opts,
-        SF#elixir_scope.macros, MacrosFun, SF),
-      SF#elixir_scope{macros=Macros}
+      { Macros, TempM } = calculate(Meta, Ref, Opts,
+        SF#elixir_scope.macros, SF#elixir_scope.macro_macros, MacrosFun, SF),
+      SF#elixir_scope{macros=Macros, macro_macros=TempM}
   end,
 
   SM.
@@ -66,9 +66,8 @@ import(Meta, Ref, Opts, Selector, S) ->
 
 %% Calculates the imports based on only and except
 
-calculate(Meta, Key, Opts, Old, AvailableFun, S) ->
+calculate(Meta, Key, Opts, Old, Temp, AvailableFun, S) ->
   File = S#elixir_scope.file,
-  All = keydelete(Key, Old),
 
   New = case keyfind(only, Opts) of
     { only, RawOnly } ->
@@ -88,20 +87,20 @@ calculate(Meta, Key, Opts, Old, AvailableFun, S) ->
           Except = expand_fun_arity(Meta, except, RawExcept, S),
           case keyfind(Key, Old) of
             false -> AvailableFun(true) -- Except;
-            {Key,ToRemove} -> ToRemove -- Except
+            {Key,OldImports} -> OldImports -- Except
           end
       end
   end,
 
   %% Normalize the data before storing it
-  Set     = ordsets:from_list(New),
-  Final   = remove_internals(Set),
+  Set   = ordsets:from_list(New),
+  Final = remove_internals(Set),
 
   case Final of
-    [] -> All;
+    [] -> { keydelete(Key, Old), keydelete(Key, Temp) };
     _  ->
       ensure_no_in_erlang_macro_conflict(Meta, File, Key, Final, internal_conflict),
-      [{ Key, Final }|All]
+      { [{ Key, Final }|keydelete(Key, Old)], [{ Key, Final }|keydelete(Key, Temp)] }
   end.
 
 %% Ensure we are expanding macros and stuff

lib/elixir/src/elixir_scope.erl

@@ -93,7 +93,8 @@ serialize(S) ->
   elixir_tree_helpers:abstract_syntax(
     { S#elixir_scope.file, S#elixir_scope.functions, S#elixir_scope.check_clauses,
       S#elixir_scope.requires, S#elixir_scope.macros, S#elixir_scope.aliases,
-      S#elixir_scope.macro_aliases, S#elixir_scope.scheduled }
+      S#elixir_scope.macro_functions, S#elixir_scope.macro_macros, S#elixir_scope.macro_aliases,
+      S#elixir_scope.scheduled }
   ).
 
 serialize_with_vars(Line, S) when is_integer(Line) ->
@@ -111,14 +112,17 @@ serialize_with_vars(Line, S) when is_integer(Line) ->
 
 deserialize(Tuple) -> deserialize_with_vars(Tuple, []).
 
-deserialize_with_vars({ File, Functions, CheckClauses, Requires, Macros, Aliases, MacroAliases, Scheduled }, Vars) ->
+deserialize_with_vars({ File, Functions, CheckClauses, Requires, Macros,
+                        Aliases, MacroFunctions, MacroMacros, MacroAliases, Scheduled }, Vars) ->
   #elixir_scope{
     file=File,
     functions=Functions,
     check_clauses=CheckClauses,
     requires=Requires,
     macros=Macros,
     aliases=Aliases,
+    macro_functions=MacroFunctions,
+    macro_macros=MacroMacros,
     macro_aliases=MacroAliases,
     scheduled=Scheduled,
     vars=orddict:from_list(Vars),

lib/elixir/test/elixir/kernel/quote_test.exs

@@ -275,4 +275,23 @@ defmodule Kernel.QuoteTest.ImportsHygieneTest do
     import Dict, only: [size: 1]
     assert get_dict_size == 2
   end
+
+  defmacrop with_size do
+    quote do
+      import Kernel, except: [size: 1]
+      import Dict, only: [size: 1]
+      size([a: 1, b: 2])
+    end
+  end
+
+  defmacrop with_nested_size do
+    quote do
+      with_size
+    end
+  end
+
+  test :explicitly_overriden_imports do
+    assert with_size == 2
+    assert with_nested_size == 2
+  end
 end