From bae10419f6e07dbde8e66ff4ff70d050f82ad451 Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Thu, 10 Mar 2022 07:41:12 +0000 Subject: [PATCH] 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. --- gcc/cp/decl.cc | 4 ++-- gcc/testsuite/g++.dg/parse/pr95999.C | 8 ++++++++ 2 files changed, 10 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/parse/pr95999.C diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 992e38385c25..58210905ee98 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -16263,7 +16263,7 @@ finish_enum_value_list (tree enumtype) /* Update the minimum and maximum values, if appropriate. */ value = DECL_INITIAL (decl); - if (value == error_mark_node) + if (TREE_CODE (value) != INTEGER_CST) value = integer_zero_node; /* Figure out what the minimum and maximum values of the enumerators are. */ @@ -16552,7 +16552,7 @@ build_enumerator (tree name, tree value, tree enumtype, tree attributes, which case the type is an unspecified integral type sufficient to contain the incremented value. */ prev_value = DECL_INITIAL (TREE_VALUE (TYPE_VALUES (enumtype))); - if (error_operand_p (prev_value)) + if (TREE_CODE (prev_value) != INTEGER_CST) value = error_mark_node; else { diff --git a/gcc/testsuite/g++.dg/parse/pr95999.C b/gcc/testsuite/g++.dg/parse/pr95999.C new file mode 100644 index 000000000000..cf8437ef2621 --- /dev/null +++ b/gcc/testsuite/g++.dg/parse/pr95999.C @@ -0,0 +1,8 @@ +/* { dg-do compile } */ +int a; +enum struct b; +template enum struct b { e }; // { dg-error "explicit specialization" } +// { dg-excess-errors "note" } +// { dg-excess-errors "5:" } + -- 2.47.2