https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123568
--- Comment #1 from Jireh Guo <jirehguo at tju dot edu.cn> --- Here is another similar test case but goes back to 10.3 with checking. Compiler Explorer: https://godbolt.org/z/Mzv7hvxf6 Code: ```cpp struct { decltype([] { struct { int f = ; ``` Stack Dump: ``` <source>: In lambda function: <source>:3:8: error: types may not be defined in 'decltype' expressions 3 | struct { | ^ <source>:4:10: error: expected '}' at end of input 4 | int f = ; | ^ <source>:3:8: note: to match this '{' 3 | struct { | ^ <source>:4:10: error: expected unqualified-id at end of input 4 | int f = ; | ^ <source>:4:10: error: expected '}' at end of input <source>:2:15: note: to match this '{' 2 | decltype([] { | ^ <source>: At global scope: <source>:2:13: error: expected ')' at end of input 2 | decltype([] { | ~ ^ | ) 3 | struct { 4 | int f = ; | <source>:4:10: error: expected unqualified-id at end of input 4 | int f = ; | ^ <source>:4:10: error: expected '}' at end of input <source>:1:8: note: to match this '{' 1 | struct { | ^ <source>:4:10: internal compiler error: in cp_lexer_new_from_tokens, at cp/parser.cc:969 4 | int f = ; | ^ 0x2950a78 diagnostics::context::diagnostic_impl(rich_location*, diagnostics::metadata const*, diagnostics::option_id, char const*, __va_list_tag (*) [1], diagnostics::kind) ???:0 0x294583b internal_error(char const*, ...) ???:0 0xb1ec34 fancy_abort(char const*, int, char const*) ???:0 0xd64c03 c_parse_file() ???:0 0xeeed49 c_common_parse_file() ???:0 Please submit a full bug report, with preprocessed source (by using -freport-bug). Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. Compiler returned: 1 ```
