Fold is_function/1,2 during compilation

This can often appear in code after inlining some higher-order
functions.

* mark is_function/2 as pure
* track function types in sys_core_fold
* use those types to eval is_function/1,2 at compile-time when possible

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl
index ab7f36abf7..00b0e4ad42 100644
--- a/lib/compiler/test/core_fold_SUITE.erl
+++ b/lib/compiler/test/core_fold_SUITE.erl
@@ -278,6 +278,8 @@ coverage(Config) when is_list(Config) ->
     a = cover_remove_non_vars_alias({a,b,c}),
     error = cover_will_match_lit_list(),
     {ok,[a]} = cover_is_safe_bool_expr(a),
+    false = cover_is_safe_bool_expr2(a),
+    ok = cover_eval_is_function(fun id/1),
 
     ok = cover_opt_guard_try(#cover_opt_guard_try{list=[a]}),
     error = cover_opt_guard_try(#cover_opt_guard_try{list=[]}),
@@ -341,6 +343,15 @@ cover_is_safe_bool_expr(X) ->
 	    false
     end.
 
+cover_is_safe_bool_expr2(X) ->
+    try
+	V = [X],
+    is_function(V, 1)
+    catch
+	_:_ ->
+	    false
+    end.
+
 cover_opt_guard_try(Msg) ->
     if
 	length(Msg#cover_opt_guard_try.list) =/= 1 ->
@@ -349,6 +360,12 @@ cover_opt_guard_try(Msg) ->
 	    ok
     end.
 
+cover_eval_is_function(X) ->
+    case X of
+        {a,_} -> is_function(X);
+        _ -> ok
+    end.
+
 bsm_an_inlined(<<_:8>>, _) -> ok;
 bsm_an_inlined(_, _) -> error.