[ty] Fix edge cases for autocomplete suppressions in variable bindings

crates/ty_ide/src/completion.rs

@@ -1315,7 +1315,8 @@ fn find_typed_text(
     if last.end() < offset || last.range().is_empty() {
         return None;
     }
-    Some(source[last.range()].to_string())
+    let range = TextRange::new(last.start(), offset);
+    Some(source[range].to_string())
 }
 
 /// Whether the last token is in a place where we should not provide completions.
@@ -1406,6 +1407,24 @@ fn is_in_variable_binding(parsed: &ParsedModuleRef, offset: TextSize, typed: Opt
             type_param.name.range.contains_range(range)
         }
         ast::AnyNodeRef::StmtFor(stmt_for) => stmt_for.target.range().contains_range(range),
+        // The AST does not produce `ast::AnyNodeRef::Parameter` nodes for keywords
+        // or otherwise invalid syntax. Rather they are captured in a
+        // `ast::AnyNodeRef::Parameters` node as "empty space". To ensure
+        // we still suppress suggestions even when the syntax is technically
+        // invalid we extract the token under the cursor and check if it makes
+        // up that "empty space" inside the Parameters Node. If it does, we know
+        // that we are still binding variables, just that the current state is
+        // syntatically invalid. Hence we suppress autocomplete suggestons
+        // also in those cases.
+        ast::AnyNodeRef::Parameters(params) => {
+            if !params.range.contains_range(range) {
+                return false;
+            }
+            params
+                .iter()
+                .map(|param| param.range())
+                .all(|r| !r.contains_range(range))
+        }
         _ => false,
     })
 }
@@ -1633,6 +1652,21 @@ mod tests {
         );
     }
 
+    #[test]
+    fn inside_token() {
+        let test = completion_test_builder(
+            "\
+foo_bar_baz = 1
+x = foo<CURSOR>bad
+",
+        );
+
+        assert_snapshot!(
+            test.skip_builtins().build().snapshot(),
+            @"foo_bar_baz",
+        );
+    }
+
     #[test]
     fn type_keyword_dedup() {
         let test = completion_test_builder(
@@ -5347,6 +5381,45 @@ def foo(p<CURSOR>
         );
     }
 
+    #[test]
+    fn no_completions_in_function_param_keyword() {
+        let builder = completion_test_builder(
+            "\
+def foo(in<CURSOR>
+",
+        );
+        assert_snapshot!(
+            builder.build().snapshot(),
+            @"<No completions found>",
+        );
+    }
+
+    #[test]
+    fn no_completions_in_function_param_multi_keyword() {
+        let builder = completion_test_builder(
+            "\
+def foo(param, in<CURSOR>
+",
+        );
+        assert_snapshot!(
+            builder.build().snapshot(),
+            @"<No completions found>",
+        );
+    }
+
+    #[test]
+    fn no_completions_in_function_param_multi_keyword_middle() {
+        let builder = completion_test_builder(
+            "\
+def foo(param, in<CURSOR>, param_two
+",
+        );
+        assert_snapshot!(
+            builder.build().snapshot(),
+            @"<No completions found>",
+        );
+    }
+
     #[test]
     fn no_completions_in_function_type_param() {
         let builder = completion_test_builder(