https://gcc.gnu.org/g:806d5417e0c04a15c48a7e876ebf435f06ecfccc
commit r16-4209-g806d5417e0c04a15c48a7e876ebf435f06ecfccc Author: Egas Ribeiro <[email protected]> Date: Fri Oct 3 01:56:52 2025 +0100 c++: Fix ICE with struct in function parameter containing auto [PR122112] When parsing function parameters containing a struct declaration, initially auto_is_implicit_function_template_parm_p is set to true by cp_parser_parameter_declaration_clause. However, later when we enter class scope and scope_kind becomes sk_class, we don't set it to false, so cp_parser_simple_type_specifier will call synthesize_implicit_template_parm, which expects that current_binding_level->kind == sk_function_parms, triggering a failed assertion. This fix ensures that auto_is_implicit_function_template_parm_p isn't set when parsing a struct body definition. gcc/cp/ChangeLog: PR c++/122112 * parser.cc (cp_parser_parameter_declaration_clause): Don't enable auto_is_implicit_function_template_parm_p when entering class scope. gcc/testsuite/ChangeLog: PR c++/122112 * g++.dg/parse/auto-struct-param.C: New test. Signed-off-by: Egas Ribeiro <[email protected]> Diff: --- gcc/cp/parser.cc | 7 +++++++ gcc/testsuite/g++.dg/parse/auto-struct-param.C | 4 ++++ 2 files changed, 11 insertions(+) diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc index 8d1187f8cdae..04031486bb3b 100644 --- a/gcc/cp/parser.cc +++ b/gcc/cp/parser.cc @@ -28124,6 +28124,7 @@ cp_parser_class_specifier (cp_parser* parser) bool in_switch_statement_p; bool saved_in_unbraced_linkage_specification_p; bool saved_in_unbraced_export_declaration_p; + bool saved_auto_is_implicit_function_template_parm_p; tree old_scope = NULL_TREE; tree scope = NULL_TREE; cp_token *closing_brace; @@ -28181,6 +28182,10 @@ cp_parser_class_specifier (cp_parser* parser) saved_in_unbraced_export_declaration_p = parser->in_unbraced_export_declaration_p; parser->in_unbraced_export_declaration_p = false; + saved_auto_is_implicit_function_template_parm_p + = parser->auto_is_implicit_function_template_parm_p; + parser->auto_is_implicit_function_template_parm_p = false; + /* 'this' from an enclosing non-static member function is unavailable. */ tree saved_ccp = current_class_ptr; tree saved_ccr = current_class_ref; @@ -28571,6 +28576,8 @@ cp_parser_class_specifier (cp_parser* parser) = saved_in_unbraced_linkage_specification_p; parser->in_unbraced_export_declaration_p = saved_in_unbraced_export_declaration_p; + parser->auto_is_implicit_function_template_parm_p + = saved_auto_is_implicit_function_template_parm_p; current_class_ptr = saved_ccp; current_class_ref = saved_ccr; diff --git a/gcc/testsuite/g++.dg/parse/auto-struct-param.C b/gcc/testsuite/g++.dg/parse/auto-struct-param.C new file mode 100644 index 000000000000..78573c685036 --- /dev/null +++ b/gcc/testsuite/g++.dg/parse/auto-struct-param.C @@ -0,0 +1,4 @@ +// PR c++/122112 +// { dg-do compile { target c++20 } } + +void func(struct { auto x; }); // { dg-error "" }
