Here we're attempting to evaluate a PTRMEM_CST in a class that hasn't been completed yet, but that doesn't work:
/* We can't lower this until the class is complete. */ if (!COMPLETE_TYPE_P (DECL_CONTEXT (member))) return cst; and then this unlowered PTRMEM_CST is used as EXPR in tree op1 = build_nop (ptrdiff_type_node, expr); and we crash in a subsequent cp_fold_convert which gets type=ptrdiff_type_node, expr=PTRMEM_CST and does else if (TREE_CODE (expr) == PTRMEM_CST && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type), PTRMEM_CST_CLASS (expr))) where TYPE_PTRMEM_CLASS_TYPE (type) is going to crash since the type is ptrdiff_type_node. We could just add a TYPE_PTRMEM_P check before accessing TYPE_PTRMEM_CLASS_TYPE but I think it's nicer to explain why we couldn't evaluate the expression. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? PR c++/107574 gcc/cp/ChangeLog: * constexpr.cc (cxx_eval_constant_expression): Emit an error when a PTRMEM_CST cannot be evaluated. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/ptrmem-cst1.C: New test. --- gcc/cp/constexpr.cc | 9 +++++++++ gcc/testsuite/g++.dg/cpp0x/ptrmem-cst1.C | 11 +++++++++++ 2 files changed, 20 insertions(+) create mode 100644 gcc/testsuite/g++.dg/cpp0x/ptrmem-cst1.C diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index 5b31f9c27d1..2c03988b097 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -7691,6 +7691,15 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t, if (!same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (op)) && !can_convert_qual (type, op)) op = cplus_expand_constant (op); + if (TREE_CODE (op) == PTRMEM_CST && !TYPE_PTRMEM_P (type)) + { + if (!ctx->quiet) + error_at (loc, "%qE is not a constant expression when the " + "class %qT is still incomplete", op, + PTRMEM_CST_CLASS (op)); + *non_constant_p = true; + return t; + } return cp_fold_convert (type, op); } diff --git a/gcc/testsuite/g++.dg/cpp0x/ptrmem-cst1.C b/gcc/testsuite/g++.dg/cpp0x/ptrmem-cst1.C new file mode 100644 index 00000000000..0d6a6b6445d --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/ptrmem-cst1.C @@ -0,0 +1,11 @@ +// PR c++/107574 +// { dg-do compile { target c++11 } } + +struct A { int i; }; +struct B:A { int j; }; +struct C:B { + int k; + static_assert((int B::*) &C::k, ""); // { dg-error "non-constant|still incomplete" } +}; + +static_assert((int B::*) &C::k, ""); base-commit: 07c87fce63541846ca2951e22dac04fcaa66475f -- 2.39.1