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The fix for bug 59195: [C++ demangler handles conversion operator incorrectly] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59195 unfortunately makes the demangler crash due to infinite recursion, in case of casts in template parameters. For example, with: template<int> struct A {}; template <typename Y> void function_temp(A<sizeof ((Y)(999))>) {} template void function_temp<int>(A<sizeof (int)>); The 'function_temp<int>' instantiation above mangles to: _Z13function_tempIiEv1AIXszcvT_Li999EEE The demangler parses this as: typed name template name 'function_temp' template argument list builtin type int function type builtin type void argument list template (*) name 'A' template argument list unary operator operator sizeof unary operator cast template parameter 0 (**) literal builtin type int name '999' And after the fix for 59195, due to: static void d_print_cast (struct d_print_info *dpi, int options, const struct demangle_component *dc) { ... /* For a cast operator, we need the template parameters from the enclosing template in scope for processing the type. */ if (dpi->current_template != NULL) { dpt.next = dpi->templates; dpi->templates = &dpt; dpt.template_decl = dpi->current_template; } when printing the template argument list of A (what should be "<sizeof (int)>"), the template parameter 0 (that is, "T_", the '**' above) now refers to the first parameter of the the template argument list of the 'A' template (the '*' above), exactly what we were already trying to print. This leads to infinite recursion, and stack exaustion. The template parameter 0 should actually refer to the first parameter of the 'function_temp' template. Where it reads "for the cast operator" in the comment in d_print_cast (above), it's really talking about a conversion operator, like: struct A { template <typename U> explicit operator U(); }; We don't want to inject the template parameters from the enclosing template in scope when processing a cast _expression_, only when handling a conversion operator. The problem is that DEMANGLE_COMPONENT_CAST is currently ambiguous, and means _both_ 'conversion operator' and 'cast expression'. Fix this by adding a new DEMANGLE_COMPONENT_CONVERSION component type, which does what DEMANGLE_COMPONENT_CAST does today, and making DEMANGLE_COMPONENT_CAST just simply print its component subtree. I think we could instead reuse DEMANGLE_COMPONENT_CAST and in d_print_comp_inner still do: @@ -5001,9 +5013,9 @@ d_print_comp_inner (struct d_print_info *dpi, int options, d_print_comp (dpi, options, dc->u.s_extended_operator.name); return; case DEMANGLE_COMPONENT_CAST: d_append_string (dpi, "operator "); - d_print_cast (dpi, options, dc); + d_print_conversion (dpi, options, dc); return; leaving the unary cast case below calling d_print_cast, but seems to me that spliting the component types makes it easier to reason about the code. g++'s testsuite actually generates three symbols that crash the demangler in the same way. I've added those as tests in the demangler testsuite as well. And then this fixes PR other/61233 too, which happens to be a demangler crash originally reported to GDB, at: https://sourceware.org/bugzilla/show_bug.cgi?id=16957 Bootstrapped and regtested on x86_64 Fedora 20. Also ran this through GDB's testsuite. GDB will require a small update to use DEMANGLE_COMPONENT_CONVERSION in one place it's using DEMANGLE_COMPONENT_CAST in its sources. libiberty/ 2015-11-27 Pedro Alves <palves@redhat.com> PR other/61321 PR other/61233 * demangle.h (enum demangle_component_type) <DEMANGLE_COMPONENT_CONVERSION>: New value. * cp-demangle.c (d_demangle_callback, d_make_comp): Handle DEMANGLE_COMPONENT_CONVERSION. (is_ctor_dtor_or_conversion): Handle DEMANGLE_COMPONENT_CONVERSION instead of DEMANGLE_COMPONENT_CAST. (d_operator_name): Return a DEMANGLE_COMPONENT_CONVERSION component if handling a conversion. (d_count_templates_scopes, d_print_comp_inner): Handle DEMANGLE_COMPONENT_CONVERSION. (d_print_comp_inner): Handle DEMANGLE_COMPONENT_CONVERSION instead of DEMANGLE_COMPONENT_CAST. (d_print_cast): Rename as ... (d_print_conversion): ... this. Adjust comments. (d_print_cast): Rewrite - simply print the left subcomponent. * cp-demint.c (cplus_demangle_fill_component): Handle DEMANGLE_COMPONENT_CONVERSION. * testsuite/demangle-expected: Add tests. From-SVN: r231020 |
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