I've backported this patch from trunk at r205292. Committed on google/gcc-4_8 branch as r207971.
Tested with make check in libiberty. -cary 2013-11-22 Cary Coutant <ccout...@google.com> libiberty/ * cp-demangle.c (struct d_info_checkpoint): New struct. (struct d_print_info): Add current_template field. (d_operator_name): Set flag when processing a conversion operator. (cplus_demangle_type): When processing <template-args> for a conversion operator, backtrack if necessary. (d_expression_1): Renamed from d_expression. (d_expression): New wrapper around d_expression_1. (d_checkpoint): New function. (d_backtrack): New function. (d_print_init): Initialize current_template. (d_print_comp): Set current_template. (d_print_cast): Put current_template in scope for printing conversion operator name. (cplus_demangle_init_info): Initialize is_expression and is_conversion. * cp-demangle.h (struct d_info): Add is_expression and is_conversion fields. * testsuite/demangle-expected: New test cases.