Merge branch 'hb/dialyzer/fix_abs_bug/OTP-12948' into maint

* hb/dialyzer/fix_abs_bug/OTP-12948:
  dialyzer: Fix erlang:abs/1

3 files changed, 106 insertions, 3 deletions

diff --git a/lib/dialyzer/test/small_SUITE_data/results/abs b/lib/dialyzer/test/small_SUITE_data/results/abs
new file mode 100644
index 0000000000..f229a6d036
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/results/abs
@@ -0,0 +1,9 @@
+
+abs.erl:12: Function i1/0 has no local return
+abs.erl:16: The pattern 'true' can never match the type 'false'
+abs.erl:23: Function i2/0 has no local return
+abs.erl:27: The pattern 'true' can never match the type 'false'
+abs.erl:34: Function i3/0 has no local return
+abs.erl:37: The pattern 'true' can never match the type 'false'
+abs.erl:45: Function i4/0 has no local return
+abs.erl:49: The pattern 'true' can never match the type 'false'
diff --git a/lib/dialyzer/test/small_SUITE_data/src/abs.erl b/lib/dialyzer/test/small_SUITE_data/src/abs.erl
new file mode 100644
index 0000000000..251e24cdfc
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/src/abs.erl
@@ -0,0 +1,71 @@
+-module(abs).
+
+%% OTP-12948. erlang:abs/1 bug fix.
+
+-export([t/0]).
+
+t() ->
+    Fs = [fun i1/0, fun i2/0, fun i3/0, fun i4/0, fun f1/0],
+    _ = [catch F() || F <- Fs],
+    ok.
+
+i1() ->
+    A = int(),
+    I1 = i1(A),
+    true = I1 < 2,
+    true = I1 < 1. % can never match
+
+-spec i1(neg_integer()) -> non_neg_integer().
+
+i1(A) when is_integer(A), A < 0 ->
+    abs(A).
+
+i2() ->
+    A = int(),
+    I2 = i2(A),
+    true = I2 < 1,
+    true = I2 < 0. % can never match
+
+-spec i2(non_neg_integer()) -> non_neg_integer().
+
+i2(A) when is_integer(A), A >= 0 ->
+    abs(A).
+
+i3() ->
+    A = int(),
+    I3 = i3(A),
+    true = I3 < -1,
+    true = I3 < 0. % can never match
+
+-spec i3(integer()) -> non_neg_integer().
+
+i3(A) when is_integer(A) ->
+    abs(A).
+
+i4() ->
+    A = int(),
+    I4 = i4(A),
+    true = I4 =:= 0 orelse I4 =:= 1,
+    true = I4 < 0 orelse I4 > 1. % can never match
+
+-spec i4(integer()) -> number().
+
+i4(A) when A =:= -1; A =:= 0; A =:= 1 ->
+    abs(A).
+
+f1() ->
+    F1 = f1(float()),
+    math:sqrt(F1).
+
+f1(A) ->
+    abs(A).
+
+-spec int() -> integer().
+
+int() ->
+    foo:bar().
+
+-spec float() -> float().
+
+float() ->
+    math:sqrt(1.0).
diff --git a/lib/hipe/cerl/erl_bif_types.erl b/lib/hipe/cerl/erl_bif_types.erl
index f49089d41c..5387edfb47 100644
--- a/lib/hipe/cerl/erl_bif_types.erl
+++ b/lib/hipe/cerl/erl_bif_types.erl
@@ -514,14 +514,15 @@ type(erlang, 'bsl', 2, Xs, Opaques) ->
 type(erlang, 'bnot', 1, Xs, Opaques) ->
  strict(erlang, 'bnot', 1, Xs,
 	 fun ([X1]) ->
-	     case arith('bnot', X1, Opaques) of
+	     case arith_bnot(X1, Opaques) of
 	       error -> t_integer();
 	       {ok, T} -> T
 	     end
 	 end, Opaques);
 %% Guard bif, needs to be here.
 type(erlang, abs, 1, Xs, Opaques) ->
-  strict(erlang, abs, 1, Xs, fun ([X]) -> X end, Opaques);
+  strict(erlang, abs, 1, Xs,
+         fun ([X1]) -> arith_abs(X1, Opaques) end, Opaques);
 %% This returns (-X)-1, so it often gives a negative result.
 %%  strict(erlang, 'bnot', 1, Xs, fun (_) -> t_integer() end, Opaques);
 type(erlang, append, 2, Xs, _Opaques) -> type(erlang, '++', 2, Xs); % alias
@@ -1927,7 +1928,7 @@ negwidth(X, N) ->
     false -> negwidth(X, N+1)
   end.
 
-arith('bnot', X1, Opaques) ->
+arith_bnot(X1, Opaques) ->
   case t_is_integer(X1, Opaques) of
     false -> error;
     true ->
@@ -1937,6 +1938,28 @@ arith('bnot', X1, Opaques) ->
 			infinity_add(infinity_inv(Min1), -1))}
   end.
 
+arith_abs(X1, Opaques) ->
+  case t_is_integer(X1, Opaques) of
+    false ->
+      case t_is_float(X1, Opaques) of
+        true -> t_float();
+        false -> t_number()
+      end;
+    true ->
+      Min1 = number_min(X1, Opaques),
+      Max1 = number_max(X1, Opaques),
+      {NewMin, NewMax} =
+        case infinity_geq(Min1, 0) of
+          true -> {Min1, Max1};
+          false ->
+            case infinity_geq(Max1, 0) of
+              true  -> {0, infinity_inv(Min1)};
+              false -> {infinity_inv(Max1), infinity_inv(Min1)}
+            end
+        end,
+      t_from_range(NewMin, NewMax)
+  end.
+
 arith_mult(Min1, Max1, Min2, Max2) ->
   Tmp_list = [infinity_mult(Min1, Min2), infinity_mult(Min1, Max2),
 	      infinity_mult(Max1, Min2), infinity_mult(Max1, Max2)],