[ruff] Avoid f-string false positives in gettext calls (RUF027)

crates/ruff_linter/resources/test/fixtures/ruff/RUF027_1.py

@@ -25,6 +25,10 @@ def negative_cases():
     json3 = "{ 'positive': 'false' }"
     alternative_formatter("{a}", a=5)
     formatted = "{a}".fmt(a=7)
+    partial = "partial sentence"
+    a = _("formatting of {partial} in a translation string is bad practice")
+    _("formatting of {partial} in a translation string is bad practice")
+    print(_("formatting of {partial} in a translation string is bad practice"))
     print(do_nothing("{a}".format(a=3)))
     print(do_nothing(alternative_formatter("{a}", a=5)))
     print(format(do_nothing("{a}"), a=5))

crates/ruff_linter/src/rules/ruff/rules/missing_fstring_syntax.rs

@@ -70,13 +70,38 @@ pub(crate) fn missing_fstring_syntax(
         }
     }
 
+    // We also want to avoid expressions that are intended to be translated.
+    if semantic.current_expressions().any(is_gettext) {
+        return;
+    }
+
     if should_be_fstring(literal, locator, semantic) {
         let diagnostic = Diagnostic::new(MissingFStringSyntax, literal.range())
             .with_fix(fix_fstring_syntax(literal.range()));
         diagnostics.push(diagnostic);
     }
 }
 
+/// Returns `true` if an expression appears to be a `gettext` call.
+///
+/// We want to avoid statement expressions and assignments related to aliases
+/// of the gettext API.
+///
+/// See <https://docs.python.org/3/library/gettext.html> for details. When one
+/// uses `_` to mark a string for translation, the tools look for these markers
+/// and replace the original string with its translated counterpart. If the
+/// string contains variable placeholders or formatting, it can complicate the
+/// translation process, lead to errors or incorrect translations.
+fn is_gettext(expr: &ast::Expr) -> bool {
+    let ast::Expr::Call(ast::ExprCall { func, .. }) = expr else {
+        return false;
+    };
+    let ast::Expr::Name(ast::ExprName { id, .. }) = func.as_ref() else {
+        return false;
+    };
+    matches!(id.as_str(), "_" | "gettext" | "ngettext")
+}
+
 /// Returns `true` if `literal` is likely an f-string with a missing `f` prefix.
 /// See [`MissingFStringSyntax`] for the validation criteria.
 fn should_be_fstring(