erl_lint: Add a deprecated warning for literal tuple funs

The run-time warning for use of tuple funs will not catch the use
of literal tuple funs, such as:

    if
	{erlang,'+'}(3,X) =:= 0 -> true;
	true -> false
    end.

Therefore, add a compile-time warning to give users some warning
before they stop working in R16.

3 files changed, 25 insertions, 13 deletions

diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index abab81d31f..648ff349a4 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -248,6 +248,8 @@ format_error({illegal_guard_local_call, {F,A}}) ->
     io_lib:format("call to local/imported function ~w/~w is illegal in guard",
 		  [F,A]);
 format_error(illegal_guard_expr) -> "illegal guard expression";
+format_error(deprecated_tuple_fun) ->
+    "tuple funs are deprecated and will be removed in R16";
 %% --- exports ---
 format_error({explicit_export,F,A}) ->
     io_lib:format("in this release, the call to ~w/~w must be written "
@@ -1914,7 +1916,8 @@ gexpr({call,Line,{remote,_Lr,{atom,_Lm,erlang},{atom,_Lf,F}},As}, Vt, St0) ->
         true -> {Asvt,St1};
         false -> {Asvt,add_error(Line, illegal_guard_expr, St1)}
     end;
-gexpr({call,L,{tuple,Lt,[{atom,Lm,erlang},{atom,Lf,F}]},As}, Vt, St) ->
+gexpr({call,L,{tuple,Lt,[{atom,Lm,erlang},{atom,Lf,F}]},As}, Vt, St0) ->
+    St = add_warning(L, deprecated_tuple_fun, St0),
     gexpr({call,L,{remote,Lt,{atom,Lm,erlang},{atom,Lf,F}},As}, Vt, St);
 gexpr({op,Line,Op,A}, Vt, St0) ->
     {Avt,St1} = gexpr(A, Vt, St0),
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index dcd622b984..9f9d97b619 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -1331,17 +1331,20 @@ guard(Config) when is_list(Config) ->
                    foo.
             ">>,
             [warn_unused_vars, nowarn_obsolete_guard],
-            {errors,[{2,erl_lint,illegal_guard_expr},
-                     {4,erl_lint,illegal_guard_expr},
-                     {6,erl_lint,illegal_guard_expr},
-                     {8,erl_lint,illegal_guard_expr},
-		     {10,erl_lint,illegal_guard_expr},
-		     {12,erl_lint,illegal_guard_expr},
-		     {14,erl_lint,illegal_guard_expr},
-		     {16,erl_lint,illegal_guard_expr},
-		     {18,erl_lint,illegal_guard_expr},
-		     {20,erl_lint,illegal_guard_expr}],
-             []}},
+            {error,[{2,erl_lint,illegal_guard_expr},
+		    {4,erl_lint,illegal_guard_expr},
+		    {6,erl_lint,illegal_guard_expr},
+		    {8,erl_lint,illegal_guard_expr},
+		    {10,erl_lint,illegal_guard_expr},
+		    {12,erl_lint,illegal_guard_expr},
+		    {14,erl_lint,illegal_guard_expr},
+		    {16,erl_lint,illegal_guard_expr},
+		    {18,erl_lint,illegal_guard_expr},
+		    {20,erl_lint,illegal_guard_expr}],
+	     [{8,erl_lint,deprecated_tuple_fun},
+	      {14,erl_lint,deprecated_tuple_fun},
+	      {20,erl_lint,deprecated_tuple_fun},
+	      {28,erl_lint,deprecated_tuple_fun}]}},
            {guard6,
             <<"-record(apa,{a=a,b=foo:bar()}).
               apa() ->
diff --git a/lib/stdlib/test/qlc_SUITE.erl b/lib/stdlib/test/qlc_SUITE.erl
index 1e74ad7727..192268f90e 100644
--- a/lib/stdlib/test/qlc_SUITE.erl
+++ b/lib/stdlib/test/qlc_SUITE.erl
@@ -2969,12 +2969,14 @@ lookup1(Config) when is_list(Config) ->
                 [3] = lookup_keys(Q)
         end, [{1,a},{3,3}])">>,
 
+      {cres,
        <<"A = 3,
           etsc(fun(E) ->
                 Q = qlc:q([X || X <- ets:table(E), A =:= {erlang,element}(1, X)]),
                 [{3,3}] = qlc:e(Q),
                 [3] = lookup_keys(Q)
         end, [{1,a},{3,3}])">>,
+       {warnings,[{3,erl_lint,deprecated_tuple_fun}]}},
 
        <<"etsc(fun(E) ->
                 A = 3,
@@ -3439,12 +3441,14 @@ lookup2(Config) when is_list(Config) ->
                  [r] = qlc:e(Q),
                  [r] = lookup_keys(Q)
          end, [{keypos,1}], [#r{}])">>,
+       {cres,
        <<"etsc(fun(E) ->
                 Q = qlc:q([element(1, X) || X <- ets:table(E), 
                                             {erlang,is_record}(X, r, 2)]),
                  [r] = qlc:e(Q),
                  [r] = lookup_keys(Q)
          end, [{keypos,1}], [#r{}])">>,
+        {warnings,[{4,erl_lint,deprecated_tuple_fun}]}},
        {cres,
         <<"etsc(fun(E) ->
                 Q = qlc:q([element(1, X) || X <- ets:table(E), 
@@ -3465,12 +3469,14 @@ lookup2(Config) when is_list(Config) ->
                  [r] = qlc:e(Q),
                  [r] = lookup_keys(Q)
          end, [{keypos,1}], [#r{}])">>,
+       {cres,
        <<"etsc(fun(E) ->
                 Q = qlc:q([element(1, X) || X <- ets:table(E), 
                                             {erlang,is_record}(X, r)]),
                  [r] = qlc:e(Q),
                  [r] = lookup_keys(Q)
-         end, [{keypos,1}], [#r{}])">>
+         end, [{keypos,1}], [#r{}])">>,
+        {warnings,[{4,erl_lint,deprecated_tuple_fun}]}}
 
        ],
     ?line run(Config, <<"-record(r, {a}).\n">>, TsR),