[cristianchiriac]

JsMacroFolder built the i18n call for t`...`, t({...}) and plural/select, then returned it without folding it. Placeholder expressions are copied verbatim into values, so a t from useLingui() nested in a placeholder was left as a tagged template on the runtime function, and at runtime i18n._() got a TemplateStringsArray and returned "". The produced call's children are now folded too, as LinguiMacroFolder does for the core macros and as #279 did for JSX. Only the call's arguments are folded (CallExpr::fold_children_with), so the produced call doesn't go through fold_call_expr a second time.

Tests (use_lingui.rs), each producing the output the issue expects:

• t`Calibrated for ${device || t`Microphone`}` → 0: device || $__({ id: "1iY5xv", message: "Microphone" }).
• The issue's other case, a nested t next to a plural placeholder.
• A nested t inside the placeholder of t({ message: ... }).

All three fail without the change, and cargo test -p lingui_macro, cargo fmt --check and cargo clippy -p lingui_macro --all-targets -- -D warnings pass. I couldn't run the extractor and native-tools crates locally, because napi-build doesn't build on my Windows GNU toolchain. CI covers those.

Fixes #284

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.42%. Comparing base (b9735d3) to head (0caec55).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #285   +/-   ##
=======================================
  Coverage   94.42%   94.42%           
=======================================
  Files          11       11           
  Lines        2529     2530    +1     
=======================================
+ Hits         2388     2389    +1     
  Misses        141      141           

Flag	Coverage Δ
unittests	94.42% <100.00%> (+<0.01%)	⬆️

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Files with missing lines	Coverage Δ
crates/lingui_macro/src/js_macro_folder.rs	98.70% <100.00%> (+<0.01%)	⬆️

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[Copilot]

🟢 Approval recommended

The localized fix preserves message construction, covers the reported regressions, and has no identified blocking issues.

0 open findings

What changed in this PR

Fixes #284 by transforming nested useLingui().t calls inside message placeholders, extending the existing nested-macro handling.

Changes:

• Folds generated call children without reprocessing the call itself.
• Adds three regression tests and snapshots covering template, plural-adjacent, and descriptor placeholders.

File	Description
crates/​lingui_macro/​tests/​use_lingui.rs	Adds three nesting regression tests.
crates/​lingui_macro/​tests/​snapshots/​use_lingui__js_use_lingui_nested_t_next_to_plural_placeholder.snap	Verifies nesting alongside a plural placeholder.
crates/​lingui_macro/​tests/​snapshots/​use_lingui__js_use_lingui_nested_t_in_placeholder.snap	Verifies nesting in a template placeholder.
crates/​lingui_macro/​tests/​snapshots/​use_lingui__js_use_lingui_nested_t_in_descriptor_placeholder.snap	Verifies nesting in a descriptor placeholder.
crates/​lingui_macro/​src/​js_macro_folder.rs	Folds generated call children to transform nested macros.

🧠 Review effort: Balanced

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