failing testcase

apps/els_lsp/priv/code_navigation/src/diagnostics_bound_var_in_pattern_maybe.erl

@@ -0,0 +1,20 @@
+%% https://github.com/erlang-ls/erlang_ls/issues/1527
+%% Only valid for OTP25 or higher
+-module(diagnostics_bound_var_in_pattern_maybe).
+
+-if(?OTP_RELEASE<27).
+-feature(maybe_expr, enable).
+-endif.
+
+-export([foo/0]).
+
+foo() ->
+    maybe
+        foo ?= bar()
+    else
+        e = Error -> Error
+          % ^- Bound variable in pattern: Error
+    end.
+
+bar() ->
+    foo.

apps/els_lsp/test/els_diagnostics_SUITE.erl

@@ -14,6 +14,7 @@
 -export([
     atom_typo/1,
     bound_var_in_pattern/1,
+    bound_var_in_pattern_maybe/1,
     bound_var_in_pattern_cannot_parse/1,
     compiler/1,
     compiler_with_behaviour/1,
@@ -193,6 +194,15 @@ init_per_testcase(TestCase, Config) when
 ->
     mock_refactorerl(),
     els_test_utils:init_per_testcase(TestCase, Config);
+init_per_testcase(TestCase, Config) when
+    TestCase =:= bound_var_in_pattern_maybe
+->
+    case ?OTP_RELEASE < 25 of
+        true ->
+            {skip, "Maybe expressions are only supported from OTP 25"};
+        false ->
+            Config
+    end;
 init_per_testcase(TestCase, Config) ->
     els_mock_diagnostics:setup(),
     els_test_utils:init_per_testcase(TestCase, Config).
@@ -363,6 +373,16 @@ bound_var_in_pattern(_Config) ->
         end,
     els_test:run_diagnostics_test(Path, Source, Errors, Warnings, Hints).
 
+%% #1527
+-spec bound_var_in_pattern_maybe(config()) -> ok.
+bound_var_in_pattern_maybe(_Config) ->
+    Path = src_path("diagnostics_bound_var_in_pattern_maybe.erl"),
+    Source = <<"BoundVarInPattern">>,
+    Errors = [],
+    Warnings = [],
+    Hints = [],
+    els_test:run_diagnostics_test(Path, Source, Errors, Warnings, Hints).
+
 -spec bound_var_in_pattern_cannot_parse(config()) -> ok.
 bound_var_in_pattern_cannot_parse(_Config) ->
     Path = src_path("diagnostics_bound_var_in_pattern_cannot_parse.erl"),