Change implementation of bit_string.concat (#314)

gleam-lang · Jun 27, 2022 · f3f9aa5 · f3f9aa5
1 parent 5abe546
commit f3f9aa5
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## Unreleased
+
+- Fixed a bug in `big_string.concat`, it now uses `erlang:list_to_bitstring`
 - The `bit_builder` module gains the `from_bit_strings` function.
 
 ## v0.22.0 - 2022-06-15

diff --git a/src/gleam_stdlib.erl b/src/gleam_stdlib.erl
@@ -163,7 +163,7 @@ string_pop_grapheme(String) ->
     end.
 
 bit_string_concat(BitStrings) ->
-    iolist_to_binary(BitStrings).
+    list_to_bitstring(BitStrings).
 
 bit_string_slice(Bin, Pos, Len) ->
     try {ok, binary:part(Bin, Pos, Len)}

diff --git a/test/gleam/bit_string_test.gleam b/test/gleam/bit_string_test.gleam
@@ -23,6 +23,14 @@ pub fn append_test() {
   |> should.equal(<<1, 2, 3, 4>>)
 }
 
+if erlang {
+  pub fn append_erlang_only_test() {
+    <<1, 2:4>>
+    |> bit_string.append(<<3>>)
+    |> should.equal(<<1, 2:4, 3>>)
+  }
+}
+
 pub fn concat_test() {
   [<<1, 2>>]
   |> bit_string.concat
@@ -33,6 +41,14 @@ pub fn concat_test() {
   |> should.equal(<<1, 2, 3, 4>>)
 }
 
+if erlang {
+  pub fn concat_erlang_only_test() {
+    [<<1, 2:4>>, <<3>>]
+    |> bit_string.concat
+    |> should.equal(<<1, 2:4, 3>>)
+  }
+}
+
 pub fn slice_test() {
   <<"hello":utf8>>
   |> bit_string.slice(0, 5)