Error on undefined variables in bitstring segments #8598
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Binary/bitstring matching allows to dynamically define the
`size` of the binary in certain conditions:
* if the `size` variable is defined prior to the pattern
match:
iex> size = 8
iex> <<a::size(size), rest::binary>> = "hello"
iex> a
104
* if the `size` variable is matched within the same
binary/bitstring match, prior to its use:
iex> <<name_size::size(8), name::binary-size(name_size), _rest::binary>> = <<5, "Frank the Walrus">>
iex> name
"Frank"
Other cases are considered illegal patterns, for example:
{name_size, <<name::binary-size(name_size), _rest::binary>>} = {5, "Frank the Walrus"}
This commit raises a `CompileError: undefined variable ...` for such cases.
josevalim
reviewed
Jan 5, 2019
josevalim
pushed a commit
that referenced
this pull request
Jan 5, 2019
Binary/bitstring matching allows to dynamically define the
`size` of the binary in certain conditions:
* if the `size` variable is defined prior to the pattern
match:
iex> size = 8
iex> <<a::size(size), rest::binary>> = "hello"
iex> a
104
* if the `size` variable is matched within the same
binary/bitstring match, prior to its use:
iex> <<name_size::size(8), name::binary-size(name_size), _rest::binary>> = <<5, "Frank the Walrus">>
iex> name
"Frank"
Other cases are considered illegal patterns, for example:
{name_size, <<name::binary-size(name_size), _rest::binary>>} = {5, "Frank the Walrus"}
This commit raises a `CompileError: undefined variable ...` for such cases.
Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
xinz
added a commit
to xinz/ex_aliyun_ots
that referenced
this pull request
Jan 17, 2019
1, Since Elixir 1.8 involves binary/bitstring matching allows to dynamically define the `size` of the binary in certain conditions [details](elixir-lang/elixir#8598), some pattern matches in `plainbuffer` need to keep update; 2, Upgrade `meck` unit test lib to fix runtime crash issue in Elixir 1.8. The above updates works fine in Elixir 1.7.4 as well.
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Closes #8589
Binary/bitstring matching allows to dynamically define the
sizeof the binary in certain conditions:if the
sizevariable is defined prior to the pattern match:if the
sizevariable is matched within the same binary/bitstring match, prior to its use:Other cases are considered illegal patterns, for example:
This commit raises a
CompileError: undefined variable ...for such cases.