Hi! As the following testcase shows, error_mark_node can appear anywhere in the ctors, and with the asserts we ICE on those during error recovery. The following patch just returns boolean_false_node in those cases, it doesn't really matter what exactly we return as long as we do't crash and ideally have some consistency.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2026-09-22 Jakub Jelinek <[email protected]> PR c++/127506 * constexpr.cc (is_within_lifetime): When val is error_mark_node, return boolean_false_node. * g++.dg/cpp26/within-lifetime13.C: New test. --- a/gcc/cp/constexpr.cc 2026-09-15 12:01:51.694090042 +0200 +++ b/gcc/cp/constexpr.cc 2026-09-21 11:58:34.593165383 +0200 @@ -2655,7 +2655,7 @@ is_within_lifetime (location_t loc, cons return boolean_false_node; continue; } - else if (val == val_uninit) + else if (val == val_uninit || val == error_mark_node) return boolean_false_node; else { @@ -2685,6 +2685,8 @@ is_within_lifetime (location_t loc, cons } if (val == val_zero_init || val == val_uninit) continue; + if (val == error_mark_node) + return boolean_false_node; gcc_assert (TREE_CODE (val) == CONSTRUCTOR); unsigned int j; tree field, value; @@ -2718,6 +2720,8 @@ is_within_lifetime (location_t loc, cons return t; if (val == val_zero_init || val == val_uninit) continue; + if (val == error_mark_node) + return boolean_false_node; if (TREE_CODE (val) == STRING_CST) return boolean_true_node; gcc_assert (TREE_CODE (val) == CONSTRUCTOR); --- a/gcc/testsuite/g++.dg/cpp26/within-lifetime13.C 2026-09-21 11:56:45.183624691 +0200 +++ b/gcc/testsuite/g++.dg/cpp26/within-lifetime13.C 2026-09-21 11:57:28.325049268 +0200 @@ -0,0 +1,20 @@ +// PR c++/127506 +// { dg-do compile { target c++20 } } + +namespace std { + template <class T> + consteval bool + is_within_lifetime (const T *p) noexcept + { + return __builtin_is_within_lifetime (p); + } +} + +struct S { char a; }; +constexpr S s = { int b; }; // { dg-error "expected" } + +bool +bar () +{ + return (!std::is_within_lifetime (&s.a)); +} Jakub
