+## ---------------------- ##
+## %union name syncline. ##
+## ---------------------- ##
+
+# Check that invalid union names are properly reported in the
+# source file.
+AT_SETUP([%union name syncline])
+AT_BISON_OPTION_PUSHDEFS
+AT_DATA([[input.y]],
+[[%union break
+{
+ char dummy;
+}
+%{
+]AT_YYERROR_DECLARE_EXTERN[
+]AT_YYLEX_DECLARE_EXTERN[
+%}
+%%
+exp: '0';
+%%
+]])
+
+AT_BISON_CHECK([-o input.c input.y])
+AT_SYNCLINES_COMPILE([input.c])
+AT_CHECK([[grep '^input.y:1' stdout]], 0, [ignore])
+AT_BISON_OPTION_POPDEFS
+AT_CLEANUP
+
+