Allow empty values in .editorconfig (#60026)

Closes https://github.com/zed-industries/zed/pull/59559
Closes https://github.com/zed-industries/zed/issues/59466

Release Notes:

- Fixed incorrect parsing of .editorconfig with empty values

Cargo.toml

@@ -585,7 +585,7 @@ dirs = "6.0"
 documented = "0.9.1"
 dotenvy = "0.15.0"
 dunce = "1.0"
-ec4rs = "1.1"
+ec4rs = { version = "1.2", features = ["allow-empty-values"] }
 emojis = "0.6.1"
 env_logger = "0.11"
 encoding_rs = "0.8"

crates/project/tests/integration/project_tests.rs

@@ -284,6 +284,15 @@ async fn test_editorconfig_support(cx: &mut gpui::TestAppContext) {
             "#,
             "d.rs": "fn d() {\n    D\n}",
         },
+        "e": {
+            ".editorconfig": r#"
+            [*.rs]
+                indent_size = 5
+                indent_style = space
+                max_line_length =
+            "#,
+            "e.rs": "fn e() {\n    E\n}",
+        },
         "README.json": "tabs are better\n",
     }));
 
@@ -315,6 +324,7 @@ async fn test_editorconfig_support(cx: &mut gpui::TestAppContext) {
     let settings_b = settings_for("b/b.rs", cx).await;
     let settings_c = settings_for("c.js", cx).await;
     let settings_d = settings_for("d/d.rs", cx).await;
+    let settings_e = settings_for("e/e.rs", cx).await;
     let settings_readme = settings_for("README.json", cx).await;
     // .editorconfig overrides .zed/settings
     assert_eq!(Some(settings_a.tab_size), NonZeroU32::new(3));
@@ -330,6 +340,13 @@ async fn test_editorconfig_support(cx: &mut gpui::TestAppContext) {
     // .editorconfig in subdirectory overrides .editorconfig in root
     assert_eq!(Some(settings_d.tab_size), NonZeroU32::new(1));
 
+    // Non-empty values in e/ are parsed and applied as usual.
+    assert_eq!(Some(settings_e.tab_size), NonZeroU32::new(5));
+    assert_eq!(settings_e.hard_tabs, false);
+    // An empty value opts out of the inherited `max_line_length = 120`,
+    // falling back to .zed/settings.json instead of rejecting the whole file.
+    assert_eq!(settings_e.preferred_line_length, 64);
+
     // "indent_size" is not set, so "tab_width" is used
     assert_eq!(Some(settings_c.tab_size), NonZeroU32::new(10));