From d1f3876e8c00a5d43a1fb02b4b2e92cab373068f Mon Sep 17 00:00:00 2001
From: Dmytro Biletskyy <dmitry@biletskyy.com>
Date: Mon, 16 Oct 2023 15:19:11 +0300
Subject: [PATCH] fix: correctly process broken code when searching local
 variables (#282)

* fix error when searching local variables in broken code

* fix test name
---
 lib/next_ls/helpers/ast_helpers/variables.ex  | 92 ++++++++++---------
 .../helpers/ast_helpers/variables_test.exs    | 26 +++++-
 2 files changed, 74 insertions(+), 44 deletions(-)

diff --git a/lib/next_ls/helpers/ast_helpers/variables.ex b/lib/next_ls/helpers/ast_helpers/variables.ex
index 8e115927..1db64841 100644
--- a/lib/next_ls/helpers/ast_helpers/variables.ex
+++ b/lib/next_ls/helpers/ast_helpers/variables.ex
@@ -9,52 +9,62 @@ defmodule NextLS.ASTHelpers.Variables do
   @spec get_variable_definition(String.t(), {integer(), integer()}) :: {atom(), {Range.t(), Range.t()}} | nil
   def get_variable_definition(file, position) do
     file = File.read!(file)
-    ast = Code.string_to_quoted!(file, columns: true)
-
-    {_ast, %{vars: vars}} =
-      Macro.traverse(
-        ast,
-        %{vars: [], symbols: %{}, sym_ranges: [], scope: []},
-        &prewalk/2,
-        &postwalk/2
-      )
-
-    Enum.find_value(vars, fn %{name: name, sym_range: range, ref_range: ref_range} ->
-      if position_in_range?(position, ref_range), do: {name, range}, else: nil
-    end)
+
+    case Code.string_to_quoted(file, columns: true) do
+      {:ok, ast} ->
+        {_ast, %{vars: vars}} =
+          Macro.traverse(
+            ast,
+            %{vars: [], symbols: %{}, sym_ranges: [], scope: []},
+            &prewalk/2,
+            &postwalk/2
+          )
+
+        Enum.find_value(vars, fn %{name: name, sym_range: range, ref_range: ref_range} ->
+          if position_in_range?(position, ref_range), do: {name, range}, else: nil
+        end)
+
+      _error ->
+        nil
+    end
   end
 
   @spec list_variable_references(String.t(), {integer(), integer()}) :: [{atom(), {Range.t(), Range.t()}}]
   def list_variable_references(file, position) do
     file = File.read!(file)
-    ast = Code.string_to_quoted!(file, columns: true)
-
-    {_ast, %{vars: vars}} =
-      Macro.traverse(
-        ast,
-        %{vars: [], symbols: %{}, sym_ranges: [], scope: []},
-        &prewalk/2,
-        &postwalk/2
-      )
-
-    symbol =
-      Enum.find_value(vars, fn %{name: name, sym_range: range, ref_range: ref_range} ->
-        if position_in_range?(position, ref_range), do: {name, range}, else: nil
-      end)
-
-    position =
-      case symbol do
-        nil -> position
-        {_, {line.._, column.._}} -> {line, column}
-      end
-
-    Enum.reduce(vars, [], fn val, acc ->
-      if position_in_range?(position, val.sym_range) do
-        [{val.name, val.ref_range} | acc]
-      else
-        acc
-      end
-    end)
+
+    case Code.string_to_quoted(file, columns: true) do
+      {:ok, ast} ->
+        {_ast, %{vars: vars}} =
+          Macro.traverse(
+            ast,
+            %{vars: [], symbols: %{}, sym_ranges: [], scope: []},
+            &prewalk/2,
+            &postwalk/2
+          )
+
+        symbol =
+          Enum.find_value(vars, fn %{name: name, sym_range: range, ref_range: ref_range} ->
+            if position_in_range?(position, ref_range), do: {name, range}, else: nil
+          end)
+
+        position =
+          case symbol do
+            nil -> position
+            {_, {line.._, column.._}} -> {line, column}
+          end
+
+        Enum.reduce(vars, [], fn val, acc ->
+          if position_in_range?(position, val.sym_range) do
+            [{val.name, val.ref_range} | acc]
+          else
+            acc
+          end
+        end)
+
+      _error ->
+        []
+    end
   end
 
   # search symbols in function and macro definition args and increase scope
diff --git a/test/next_ls/helpers/ast_helpers/variables_test.exs b/test/next_ls/helpers/ast_helpers/variables_test.exs
index e8065aab..63019566 100644
--- a/test/next_ls/helpers/ast_helpers/variables_test.exs
+++ b/test/next_ls/helpers/ast_helpers/variables_test.exs
@@ -143,7 +143,17 @@ defmodule NextLS.ASTHelpers.VariablesTest do
     end
     """)
 
-    [source: source]
+    broken = Path.join(tmp_dir, "my_proj/lib/broken.ex")
+
+    File.write!(broken, """
+    defmodule Broken do
+      def foo(bar) do
+        {:ok, bar}
+      end
+    # end
+    """)
+
+    [source: source, broken: broken]
   end
 
   describe "get_variable_definition/2" do
@@ -154,12 +164,17 @@ defmodule NextLS.ASTHelpers.VariablesTest do
 
     test "returns nil when position is not a variable reference", %{source: source} do
       symbol = Variables.get_variable_definition(source, {7, 6})
-      assert symbol == nil
+      refute symbol
     end
 
     test "returns nil when position is a variable symbol", %{source: source} do
       symbol = Variables.get_variable_definition(source, {5, 5})
-      assert symbol == nil
+      refute symbol
+    end
+
+    test "returns nil when source code is broken", %{broken: broken} do
+      symbol = Variables.get_variable_definition(broken, {1, 10})
+      refute symbol
     end
   end
 
@@ -332,5 +347,10 @@ defmodule NextLS.ASTHelpers.VariablesTest do
       assert length(refs3) == 1
       assert {:var, {127..127, 17..19}} in refs3
     end
+
+    test "returns empty list when source code is broken", %{broken: broken} do
+      symbol = Variables.list_variable_references(broken, {2, 10})
+      assert Enum.empty?(symbol)
+    end
   end
 end