Always rewrite signed numbers during expansion #12955
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josevalim
reviewed
Sep 23, 2023
| %% care about Erlang ones. | ||
| match_rewrite(erlang, _, '+', _, [Arg]) when is_number(Arg) -> {ok, Arg}; | ||
| match_rewrite(erlang, _, '-', _, [Arg]) when is_number(Arg) -> {ok, -Arg}; | ||
| match_rewrite(erlang, _, '++', Meta, [Left, Right]) -> |
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Can you please do a check later that we still need this one? I think recent Erlang versions started inlining ++ as well. :) It may be we can get rid of match_rewrite altogether!
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Sounds good, will definitely check!
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OK, I tried for a while but I don't think we can reasonably remove it without introducing regressions.
Issue 1: Elixir's current inlining is more powerful
iex(5)> [a] ++ bc = 'abc'
~c"abc"1> [A] ++ BC = "abc".
* 1:5: illegal pattern
2> "a" ++ BC = "abc".
"abc"Issue 2: Rewrite currently serves as validation, will need to translate more erlang errors
Currently:
iex(1)> "a" ++ "b" = "ab"
error: invalid argument for ++ operator inside a match, expected a literal proper list, got: "a"Relying on erlang's inlining:
iex(1)> "a" ++ "b" = "ab"
** (ErlangError) Erlang error: {:illegal_pattern, {:op, 1, :++, {:bin, 1, [{:bin_element, 1, {:string, 1, ~c"a"}, :default, :default}]}, {:bin, 1, [{:bin_element, 1, {:string, 1, ~c"b"}, :default, :default}]}}}
josevalim
approved these changes
Sep 23, 2023
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Simplify emitted erlang AST for signed numbers following discussions in #12949.
Before,
-1would be:{:integer, _, -1}in matches{:op, _, :-, {:integer, _, 1}}otherwiseWith this PR:
{:integer, _, -1}, always