https://gcc.gnu.org/g:a918fbf3114d1663ac8d96c3fbcc29c790ad6350
commit r15-10845-ga918fbf3114d1663ac8d96c3fbcc29c790ad6350 Author: Patrick Palka <[email protected]> Date: Thu Feb 12 14:44:56 2026 -0500 c++: evaluation order of xobj memfn call [PR123989] The object argument of an xobj memfn call needs to be evaluated before its formal arguments, like with an iobj memfn call. This patch generalizes the existing such handling in cp_gimplify_expr for METHOD_TYPE callees to also accept xobj memfn callees. PR c++/123989 gcc/cp/ChangeLog: * cp-gimplify.cc (cp_gimplify_expr) <case CALL_EXPR>: Evaluate the object argument of an xobj memfn call first too. gcc/testsuite/ChangeLog: * g++.dg/cpp23/explicit-obj-eval-order.C: New test. Reviewed-by: Marek Polacek <[email protected]> Reviewed-by: Jason Merrill <[email protected]> (cherry picked from commit 0d51ed19504bcaa540763423763bb97227ed6c1c) Diff: --- gcc/cp/cp-gimplify.cc | 10 +++++++++- gcc/testsuite/g++.dg/cpp23/explicit-obj-eval-order.C | 16 ++++++++++++++++ 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc index 5363ec83ff41..202a83eafb2f 100644 --- a/gcc/cp/cp-gimplify.cc +++ b/gcc/cp/cp-gimplify.cc @@ -845,7 +845,15 @@ cp_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p) tree fntype = TREE_TYPE (CALL_EXPR_FN (*expr_p)); if (INDIRECT_TYPE_P (fntype)) fntype = TREE_TYPE (fntype); - if (TREE_CODE (fntype) == METHOD_TYPE) + tree decl = cp_get_callee_fndecl_nofold (*expr_p); + /* We can't just rely on 'decl' because virtual function callees + are expressed as OBJ_TYPE_REF. Note that the xobj memfn check + will also hold for calls of the form (&A::f)(a, ...) which does + not require such sequencing, though it's allowed under + "indeterminately sequenced". */ + if (TREE_CODE (fntype) == METHOD_TYPE + || (decl && DECL_LANG_SPECIFIC (decl) + && DECL_XOBJ_MEMBER_FUNCTION_P (decl))) { int nargs = call_expr_nargs (*expr_p); bool side_effects = false; diff --git a/gcc/testsuite/g++.dg/cpp23/explicit-obj-eval-order.C b/gcc/testsuite/g++.dg/cpp23/explicit-obj-eval-order.C new file mode 100644 index 000000000000..7ce81f32cc4b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp23/explicit-obj-eval-order.C @@ -0,0 +1,16 @@ +// PR c++/123989 +// { dg-do run { target c++23 } } + +struct A { + int m = 42; + + void f(this A self, int n) { + if (self.m != 42 || n != 43) + __builtin_abort(); + } +}; + +int main() { + A a; + a.f(++a.m); +}
