Preserve aggregate initializer temporary lifetimes

src/decl_inits.c

@@ -4704,12 +4704,17 @@ initializer, already copied and substituted.
   a_routine_ptr          dtor_rp = NULL;
   a_boolean              need_to_free_icp_tree = FALSE;
   a_boolean              saved_reduce_backing_expression_use;
+  an_expr_stack_entry     expr_stack_entry, *saved_expr_stack;
+  a_boolean              full_expression;
 
   check_assertion(rescan_aggr != NULL || curr_token == tok_lbrace ||
                   (dps != NULL &&
                    anything_cached(&dps->prescanned_initializer_cache)));
   saved_reduce_backing_expression_use = reduce_backing_expression_use;
   dtype = skip_typerefs(dtype);
+  full_expression = !C_mode() && is->elements_are_full_expressions &&
+                    is_aggregate_type(dtype) &&
+                    !(dps != NULL && dps->is_struct_binding_decl);
   if (rescan_aggr != NULL) {
     /* Rescan.  The {...} is provided by the caller in init-component form. */
     icp_tree = rescan_aggr;
@@ -4728,6 +4733,12 @@ initializer, already copied and substituted.
   }  /* if */
   icp = icp_tree;
   check_assertion(icp != NULL && is_braced_init_component(icp));
+  if (full_expression) {
+    /* All elements share the lifetime of the complete initialization. */
+    push_expr_stack_for_initializer(&expr_stack_entry, &saved_expr_stack,
+                                    ek_normal,
+                                    /*is_full_expr=*/TRUE, dps, is);
+  }  /* if */
   is_var_init = dps != NULL && dps->sym != NULL &&
                 variable_for_symbol(dps->sym) != NULL;
   /* The force_dynamic_init flag only applies to the top-level result. */
@@ -4933,6 +4944,17 @@ initializer, already copied and substituted.
   }  /* if */
   is->no_diagnostics = saved_no_diagnostics;
   reduce_backing_expression_use = saved_reduce_backing_expression_use;
+  if (full_expression) {
+    if (is->init_dip != NULL) {
+      wrap_up_dynamic_init_full_expression(is->init_dip);
+    } else if (is->init_error) {
+      discard_curr_expr_object_lifetime();
+    } else if (is->init_con != NULL) {
+      wrap_up_constant_full_expression(is->init_con);
+    }  /* if */
+    pop_expr_stack_for_initializer(saved_expr_stack,
+                                  /*is_full_expr=*/TRUE, dps, is);
+  }  /* if */
 }  /* braced_initializer */
 
 

src/expr.c

@@ -47957,11 +47957,13 @@ free the components prior to prev_icp.
   an_expr_stack_entry         *saved_expr_stack;
   an_expr_stack_entry         expr_stack_entry;
   an_object_lifetime          *saved_object_lifetime = curr_object_lifetime;
+  a_boolean                  saved_full_expressions;
 
   check_assertion(is_continuation_elem(prev_icp->next));
   continuation = prev_icp->next->variant.continuation.state;
   dps = continuation->decl_parse_state;
   check_assertion(dps != NULL && dps->init_state.pending_elements);
+  saved_full_expressions = dps->init_state.elements_are_full_expressions;
   if (continuation->resumable) {
     /* Free most init components preceding prev_icp, but keep the first one in
        case it is useful for diagnostic purposes. */
@@ -47996,6 +47998,7 @@ free the components prior to prev_icp.
                                     /*bundle=*/TRUE, &continuation);
   pop_expr_stack_for_initializer(saved_expr_stack, /*is_full_expr=*/TRUE,
                                  dps, (an_init_state *)NULL);
+  dps->init_state.elements_are_full_expressions = saved_full_expressions;
   if (continuation != NULL) {
     /* Parsing was suspended again.  Record additional state information to
        enable a subsequent call to this function. */

src/lower_init.c

@@ -11022,6 +11022,8 @@ do_assignment:;
       /* coverity[uninit_use] */
       if ((dip->kind == (a_dynamic_init_kind)dik_nonconstant_aggregate ||
            dip->kind == (a_dynamic_init_kind)dik_lambda) &&
+          /* Inner partial cleanups are handled by add_dyn_init_cleanup. */
+          !dip->overlaps_temps_in_inner_lifetime &&
           latest_initialization_on_entry !=
                                           eff_context->latest_initialization) {
         /* This is an aggregate for which some partial-aggregate

src/pending_changes/edg-29057-aggregate-temporary-lifetime.txt

@@ -0,0 +1,5 @@
+[GH #458]
+Preserve aggregate initializer temporary lifetimes
+
+Temporaries created while initializing an aggregate now remain alive until
+the complete initialization ends, including nested aggregate initializers.

tests/tests/regressions/edg-29057.sft.cpp

@@ -0,0 +1,21 @@
+//type:rp
+//options_all:--c++20
+//options:--g++ --gnu_version=130300:--strict
+int live, fails;
+struct Temp { Temp() { ++live; } ~Temp() { --live; } };
+struct A { A(const Temp&) {} };
+struct Pair { A a; int b; };
+int check(int expected) { fails += live != expected; return 0; }
+Pair make_pair() { return {A(Temp{}), check(1)}; }
+int main() {
+  Pair p{A(Temp{}), check(1)};
+  check(0);
+  Pair q = make_pair();
+  check(0);
+  Pair a[2]{{A(Temp{}), check(1)}, {A(Temp{}), check(2)}};
+  check(0);
+  struct Nested { Pair p; int c; } n{{A(Temp{}), check(1)}, check(1)};
+  check(0);
+  (void)p; (void)q; (void)a; (void)n;
+  return fails;
+}