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Fix false positive with nested shadowed alias #13564

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Merged
merged 4 commits into from
May 16, 2024
Merged

Fix false positive with nested shadowed alias #13564

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36aa15a
Fix false positive with nested shadowed alias
sabiwara May 16, 2024
493727c
Send less data to the genserver
sabiwara May 16, 2024
9ac6c17
Revert "Send less data to the genserver"
sabiwara May 16, 2024
4b835b6
Use function? boolean to send less data
sabiwara May 16, 2024
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14 changes: 9 additions & 5 deletions lib/elixir/lib/kernel/lexical_tracker.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,8 @@ defmodule Kernel.LexicalTracker do
end

@doc false
def add_alias(pid, module, meta, warn) when is_atom(module) do
:gen_server.cast(pid, {:add_alias, module, meta, warn})
def add_alias(pid, module, meta, warn, function) when is_atom(module) do
:gen_server.cast(pid, {:add_alias, module, meta, warn, function})
end

@doc false
Expand Down Expand Up @@ -225,12 +225,16 @@ defmodule Kernel.LexicalTracker do
end
end

def handle_cast({:add_alias, module, meta, warn}, state) do
def handle_cast({:add_alias, module, meta, warn, function}, state) do
if warn do
state =
case state do
%{aliases: %{^module => meta}} -> put_in(state.aliases[{:shadowed, module}], meta)
_ -> state
# we only track shadowed unused aliases at the top-level
%{aliases: %{^module => meta}} when function == nil ->
put_in(state.aliases[{:shadowed, module}], meta)

_ ->
state
end

{:noreply, put_in(state.aliases[module], meta)}
Expand Down
4 changes: 2 additions & 2 deletions lib/elixir/src/elixir_lexical.erl
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Expand Up @@ -40,8 +40,8 @@ trace({import, Meta, Module, Opts}, #{lexical_tracker := Pid}) ->

?tracker:add_import(Pid, Module, Only, Meta, Imported and should_warn(Meta, Opts)),
ok;
trace({alias, Meta, _Old, New, Opts}, #{lexical_tracker := Pid}) ->
?tracker:add_alias(Pid, New, Meta, should_warn(Meta, Opts)),
trace({alias, Meta, _Old, New, Opts}, #{lexical_tracker := Pid, function := Function}) ->
?tracker:add_alias(Pid, New, Meta, should_warn(Meta, Opts), Function),
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Super massive nitpick:

Suggested change
?tracker:add_alias(Pid, New, Meta, should_warn(Meta, Opts), Function),
?tracker:add_alias(Pid, New, Meta, should_warn(Meta, Opts), Function /= nil),

So we send less data to the GenServer. :)

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@sabiwara sabiwara May 16, 2024 •
edited
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493727c too much, WDYT?
Since both variables were about how to warn. Might also be less confusing than the double bool.

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Too much in my opinion. I feel like I need to undo the warn logic when I have to understand its impact in the lexical tracker. While checking for warn and function? had a clearer meaning to me. WDYT?

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@sabiwara sabiwara May 16, 2024 •
edited
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I'm fine either way.

I liked the idea of having the emitting part decide what to warn, with atom names to explain, and the receiving part just following instructions.

The downside with the non-bool atom is that I needed to come up with names (not fully satisfied with :except_unused_shadowed), and also that we'd probably need guards to make sure we don't emit something else and end up with some random accidental behavior. Finally, consistency with other messages of the module is also a strong point to keep booleans.

Will revert to the double bool!

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4b835b6

ok;
trace({alias_expansion, _Meta, Lookup, _Result}, #{lexical_tracker := Pid}) ->
?tracker:alias_dispatch(Pid, Lookup),
Expand Down
8 changes: 4 additions & 4 deletions lib/elixir/test/elixir/kernel/lexical_tracker_test.exs
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Expand Up @@ -52,7 +52,7 @@ defmodule Kernel.LexicalTrackerTest do
end

test "can add aliases", config do
D.add_alias(config[:pid], String, 1, true)
D.add_alias(config[:pid], String, 1, true, nil)
D.alias_dispatch(config[:pid], String)
assert D.references(config[:pid]) == {[], [], [], []}
end
Expand Down Expand Up @@ -93,18 +93,18 @@ defmodule Kernel.LexicalTrackerTest do
end

test "unused aliases", config do
D.add_alias(config[:pid], String, 1, true)
D.add_alias(config[:pid], String, 1, true, nil)
assert D.collect_unused_aliases(config[:pid]) == [{String, 1}]
end

test "used aliases are not unused", config do
D.add_alias(config[:pid], String, 1, true)
D.add_alias(config[:pid], String, 1, true, nil)
D.alias_dispatch(config[:pid], String)
assert D.collect_unused_aliases(config[:pid]) == []
end

test "aliases with no warn are not unused", config do
D.add_alias(config[:pid], String, 1, false)
D.add_alias(config[:pid], String, 1, false, nil)
assert D.collect_unused_aliases(config[:pid]) == []
end

Expand Down
17 changes: 17 additions & 0 deletions lib/elixir/test/elixir/kernel/warning_test.exs
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Expand Up @@ -910,6 +910,23 @@ defmodule Kernel.WarningTest do
purge(Sample)
end

test "does not warn when shadowing alias in nested block" do
assert capture_compile("""
defmodule Sample do
alias Foo.Baz

def foo do
alias Bar.Baz
Baz
end

def baz, do: Baz
end
""") == ""
after
purge(Sample)
end

test "unused inside dynamic module" do
import List, only: [flatten: 1], warn: false

Expand Down