Fix +/1 (unary plus) not implemented #1512

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added `esp:partition_read/3`, and documentation for `esp:partition_erase_range/2/3` and `esp:partition_write/3`
 - Added support for list insertion in 'ets:insert/2'.
 - Support to OTP-28
+- Added `erlang:+/1`
 
 ### Fixed
 - ESP32: improved sntp sync speed from a cold boot.

src/libAtomVM/bif.c

@@ -497,6 +497,17 @@ term bif_erlang_add_2(Context *ctx, uint32_t fail_label, int live, term arg1, te
     }
 }
 
+term bif_erlang_plus_1(Context *ctx, uint32_t fail_label, int live, term arg1)
+{
+    UNUSED(live);
+
+    if (LIKELY(term_is_number(arg1))) {
+        return arg1;
+    } else {
+        RAISE_ERROR_BIF(fail_label, BADARITH_ATOM);
+    }
+}
+
 static term sub_overflow_helper(Context *ctx, uint32_t fail_label, uint32_t live, term arg1, term arg2)
 {
     avm_int_t val1 = term_to_int(arg1);

src/libAtomVM/bif.h

@@ -70,6 +70,7 @@ term bif_erlang_map_size_1(Context *ctx, uint32_t fail_label, int live, term arg
 term bif_erlang_map_get_2(Context *ctx, uint32_t fail_label, term arg1, term arg2);
 
 term bif_erlang_add_2(Context *ctx, uint32_t fail_label, int live, term arg1, term arg2);
+term bif_erlang_plus_1(Context *ctx, uint32_t fail_label, int live, term arg1);
 term bif_erlang_sub_2(Context *ctx, uint32_t fail_label, int live, term arg1, term arg2);
 term bif_erlang_mul_2(Context *ctx, uint32_t fail_label, int live, term arg1, term arg2);
 term bif_erlang_div_2(Context *ctx, uint32_t fail_label, int live, term arg1, term arg2);

src/libAtomVM/bifs.gperf

@@ -72,6 +72,7 @@ erlang:*/2, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif2_ptr = bif_erlan
 erlang:div/2, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif2_ptr = bif_erlang_div_2}
 erlang:rem/2, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif2_ptr = bif_erlang_rem_2}
 erlang:-/1, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif1_ptr = bif_erlang_neg_1}
+erlang:+/1, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif1_ptr = bif_erlang_plus_1}
 erlang:abs/1, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif1_ptr = bif_erlang_abs_1}
 erlang:ceil/1, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif1_ptr = bif_erlang_ceil_1}
 erlang:floor/1, {.gcbif.base.type = GCBIFFunctionType, .gcbif.gcbif1_ptr = bif_erlang_floor_1}

tests/erlang_tests/CMakeLists.txt

@@ -292,6 +292,7 @@ compile_erlang(int28mulneg2)
 compile_erlang(negdiv)
 compile_erlang(absovf)
 compile_erlang(negovf)
+compile_erlang(unary_plus)
 
 compile_erlang(plusone3)
 compile_erlang(plusone4)
@@ -771,6 +772,7 @@ add_custom_target(erlang_test_modules DEPENDS
     negdiv.beam
     absovf.beam
     negovf.beam
+    unary_plus.beam
 
     plusone3.beam
     plusone4.beam

tests/erlang_tests/unary_plus.erl

@@ -0,0 +1,45 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2025 migmatore <[email protected]>
+%
+% Licensed under the Apache License, Version 2.0 (the "License");
+% you may not use this file except in compliance with the License.
+% You may obtain a copy of the License at
+%
+%    http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS,
+% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+% See the License for the specific language governing permissions and
+% limitations under the License.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+-module(unary_plus).
+
+-export([start/0, unary_plus_int/1, unary_plus_float/1, unary_plus_str/1]).
+
+start() ->
+    ok = ?MODULE:unary_plus_int(1621436),
+    ok = ?MODULE:unary_plus_float(1135.12523),
+    ok = ?MODULE:unary_plus_str("string"),
+    0.
+
+unary_plus_int(A) ->
+    +A,
+    ok.
+
+unary_plus_float(A) ->
+    +A,
+    ok.
+
+unary_plus_str(A) ->
+    try +A of
+        ok -> error
+    catch
+        error:badarith -> ok;
+        _:_ -> error
+    end.

tests/test.c

@@ -334,6 +334,7 @@ struct Test tests[] = {
     TEST_CASE_EXPECTED(negdiv, 134217728),
     TEST_CASE_EXPECTED(absovf, 134217728),
     TEST_CASE_EXPECTED(negovf, 134217728),
+    TEST_CASE(unary_plus),
 
     TEST_CASE_EXPECTED(plusone3, 134217726),
     TEST_CASE_EXPECTED(plusone4, 134217728),