fix: don't warn about missing id when a spread is present

[mogelbrod]

Description

Code like below currently triggers a "Missing message ID, skipping" warning on lingui extract, even though it works and is a decent workaround to use placeholders in lazy lookups:

const lookup = {
  x: msg`x {val}`,
  generic: msg`generic {val}`,
}

function X() {
  const { i18n } = useI18n()
  return i18n._({
    ...(lookup.x ?? lookup.generic),
    values: { val: 'test' },
  })
}

I'd like to propose that we stop reporting missing IDs when a spread is also present in the object passed to the i18n._ call.

If this is accepted I'll happily provide patches for the experimental extractor along with the SWC extractor.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Examples update

Checklist

• I have read the CONTRIBUTING and CODE_OF_CONDUCT docs
• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary documentation (if appropriate)

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Project	Deployment	Actions	Updated (UTC)
js-lingui	Ready	Preview	Jun 24, 2026 4:35pm

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.79%. Comparing base (6bb8983) to head (d2f1b42).
⚠️ Report is 354 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2581       +/-   ##
===========================================
+ Coverage   77.05%   89.79%   +12.74%     
===========================================
  Files          84      124       +40     
  Lines        2157     3695     +1538     
  Branches      555     1110      +555     
===========================================
+ Hits         1662     3318     +1656     
+ Misses        382      339       -43     
+ Partials      113       38       -75     

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[andrii-bodnar]

@mogelbrod thank you!

[andrii-bodnar]

@mogelbrod would you create subsequent fixes for the SWC and experimental extractor?

[mogelbrod]

@mogelbrod would you create subsequent fixes for the SWC and experimental extractor?

Thanks, Will do @andrii-bodnar!

[timofei-iatsenko]

@mogelbrod

experimental extractor

Rather into my branch with new rust extractor, lingui/swc-plugin#236

[mogelbrod]

Rather into my branch with new rust extractor, lingui/swc-plugin#236

@timofei-iatsenko I do not seem to be able to open a PR stacked against your swc-plugin branch as it's a fork 🙁

The following patch should address this and apply cleanly on top of the latest pushed commit in that PR:

diff --git a/crates/lingui_extractor/src/message_extractor_visitor.rs b/crates/lingui_extractor/src/message_extractor_visitor.rs
index a5949fa..97e04e3 100644
--- a/crates/lingui_extractor/src/message_extractor_visitor.rs
+++ b/crates/lingui_extractor/src/message_extractor_visitor.rs
@@ -330,6 +330,16 @@ impl<'a> MessageExtractorVisitor<'a> {
         let raw = extract_from_object_expression(obj, &mut self.warnings);
 
         if raw.id.is_none() {
+            // The id may be provided by a spread element (e.g. `i18n._({ ...msg })`),
+            // which can't be resolved statically. Skip silently instead of warning.
+            let has_spread = obj
+                .props
+                .iter()
+                .any(|prop| matches!(prop, PropOrSpread::Spread(_)));
+            if has_spread {
+                return;
+            }
+
             let loc = self.source_map.span_to_string(span);
             self.warnings
                 .push(format!("{loc}: Missing message ID, skipping."));
diff --git a/crates/lingui_extractor/tests/message_extractor.rs b/crates/lingui_extractor/tests/message_extractor.rs
index 247e1a9..81e3df3 100644
--- a/crates/lingui_extractor/tests/message_extractor.rs
+++ b/crates/lingui_extractor/tests/message_extractor.rs
@@ -84,6 +84,21 @@ import { Trans } from "@lingui/react";
     assert!(warnings.iter().any(|w| w.contains("Missing message ID")));
 }
 
+#[test]
+fn test_no_warning_when_id_could_be_provided_via_spread() {
+    let code = r#"
+const lookup = { x: {}, generic: {} };
+i18n._({
+  ...(lookup.x ?? lookup.generic),
+  values: { val: "test" },
+});
+    "#;
+
+    let (messages, warnings) = extract_and_sort(code, "test.js");
+    assert_no_warnings(&warnings);
+    assert_eq!(messages.len(), 0);
+}
+
 #[test]
 fn test_call_expression_i18n_underscore() {
     let code = r#"

[mogelbrod]

@mogelbrod would you create subsequent fixes for the SWC and experimental extractor?

It looks like the experimental babel extractor uses the already patched extractFromMessageDescriptor, so it doesn't appear to need any change.