https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95999
--- Comment #3 from CVS Commits ---
The master branch has been updated by Roger Sayle :
https://gcc.gnu.org/g:bae10419f6e07dbde8e66ff4ff70d050f82ad451
commit r12-7574-gbae10419f6e07dbde8e66ff4ff70d050f82ad451
Author: Roger Sayle
Date: Thu Mar 10 07:41:12 2022 +
PR c++/95999: Improved error recovery in enumeration lists.
This patch resolves PR c++/95999 which is an ICE-after-error regression
in the g++ front-end. When parsing an enumerator list, the C++ parser
assumes that cp_parser_constant_expression always returns either an
INTEGER_CST or error_mark_node, but in the testcase reported in the
PR, it actually returns a VAR_DECL.
The usual (but perhaps controversial) design philosophy is that the
routine that reports the error normally has a duty to indicate this to
the rest of the compiler (via error_mark_node), but here the return
value from calling require_rvalue_constant_expression (parser.cc:10666)
is ignored. I initially experimented with setting EXPRESSION to
error_mark_node here in cp_parser_constant_expression but (perhaps
conveniently) that's insufficient to resolve the problem. The simple
fix in this patch is to tweak the two places that require INTEGER_CST
to treat all other tree types as though they are error_mark_node.
2022-03-10 Roger Sayle
gcc/cp/ChangeLog
PR c++/95999
* decl.cc (finish_enum_value_list): If VALUE isn't an INTEGER_CST
consider it to be zero (i.e. treat it like error_mark_node).
(build_enumerator): Likewise, if PREV_VALUE isn't an INTEGER_CST,
set VALUE to error_mark_node.
gcc/testsuite/ChangeLog
PR c++/95999
* g++.dg/parse/pr95999.C: New test case.
