compiler: Validate Map src

Reject all expressions that are known to fail.
Emit 'badarg' for those expressions.

Ex.

    []#{ a => 1}

Is not a valid map update expression.

1 files changed, 30 insertions, 4 deletions

diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index d00dd56f30..ecff01c4e5 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -272,9 +272,18 @@ expr(#c_cons{anno=A,hd=Ch,tl=Ct}, Sub, St0) ->
 expr(#c_tuple{anno=A,es=Ces}, Sub, St0) ->
     {Kes,Ep,St1} = atomic_list(Ces, Sub, St0),
     {#k_tuple{anno=A,es=Kes},Ep,St1};
-expr(#c_map{anno=A,var=Var0,es=Ces}, Sub, St0) ->
-    {Var,[],St1} = expr(Var0, Sub, St0),
-    map_split_pairs(A, Var, Ces, Sub, St1);
+expr(#c_map{anno=A,var=Var,es=Ces}, Sub, St0) ->
+    try expr_map(A,Var,Ces,Sub,St0) of
+	{_,_,_}=Res -> Res
+    catch
+	throw:bad_map ->
+	    St1 = add_warning(get_line(A), bad_map, A, St0),
+	    Erl = #c_literal{val=erlang},
+	    Name = #c_literal{val=error},
+	    Args = [#c_literal{val=badarg}],
+	    Error = #c_call{anno=A,module=Erl,name=Name,args=Args},
+	    expr(Error, Sub, St1)
+    end;
 expr(#c_binary{anno=A,segments=Cv}, Sub, St0) ->
     try atomic_bin(Cv, Sub, St0) of
 	{Kv,Ep,St1} ->
@@ -496,6 +505,21 @@ translate_match_fail_1(Anno, As, Sub, #kern{ff=FF}) ->
 translate_fc(Args) ->
     [#c_literal{val=function_clause},make_list(Args)].
 
+expr_map(A,Var0,Ces,Sub,St0) ->
+    %% An extra pass of validation of Map src because of inlining
+    {Var,Mps,St1} = expr(Var0, Sub, St0),
+    case is_valid_map_src(Var) of
+	true ->
+	    {Km,Eps,St2} = map_split_pairs(A, Var, Ces, Sub, St1),
+	    {Km,Eps++Mps,St2};
+	false -> throw(bad_map)
+    end.
+
+is_valid_map_src(#k_map{}) -> true;
+is_valid_map_src(#k_literal{val=M}) when is_map(M) -> true;
+is_valid_map_src(#k_var{}) -> true;
+is_valid_map_src(_) -> false.
+
 map_split_pairs(A, Var, Ces, Sub, St0) ->
     %% two steps
     %% 1. force variables
@@ -1986,7 +2010,9 @@ format_error(nomatch_shadow) ->
 format_error(bad_call) ->
     "invalid module and/or function name; this call will always fail";
 format_error(bad_segment_size) ->
-    "binary construction will fail because of a type mismatch".
+    "binary construction will fail because of a type mismatch";
+format_error(bad_map) ->
+    "map construction will fail because of a type mismatch".
 
 add_warning(none, Term, Anno, #kern{ws=Ws}=St) ->
     File = get_file(Anno),