Lifetime of temporaries in aggregate initialization [GH #515]

src/decl_inits.c

@@ -4704,12 +4704,27 @@ 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);
+  is_var_init = dps != NULL && dps->sym != NULL &&
+                variable_for_symbol(dps->sym) != NULL;
+  /* In C++, the elements of a braced aggregate initializer are not separate
+     full-expressions: Temporaries created for them are destroyed when the
+     initialization of the whole aggregate is complete.  GCC versions before
+     12 and MSVC instead destroy them at the end of each element in the
+     initializer of a variable (but not in other contexts, such as
+     mem-initializers and new-expressions). */
+  full_expression = !C_mode() && is->elements_are_full_expressions &&
+                    is_aggregate_type(dtype) &&
+                    !(dps != NULL && dps->is_struct_binding_decl) &&
+                    !(is_var_init &&
+                      (gpp_version_is(<120000) || microsoft_mode));
   if (rescan_aggr != NULL) {
     /* Rescan.  The {...} is provided by the caller in init-component form. */
     icp_tree = rescan_aggr;
@@ -4728,8 +4743,12 @@ initializer, already copied and substituted.
   }  /* if */
   icp = icp_tree;
   check_assertion(icp != NULL && is_braced_init_component(icp));
-  is_var_init = dps != NULL && dps->sym != NULL &&
-                variable_for_symbol(dps->sym) != NULL;
+  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 */
   /* The force_dynamic_init flag only applies to the top-level result. */
   is->force_dynamic_init = FALSE;
   if (is_template_dependent_context() && is_variadic_template_context() &&
@@ -4933,6 +4952,17 @@ 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

@@ -48020,11 +48020,13 @@ 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. */
@@ -48059,6 +48061,7 @@ 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

@@ -11048,6 +11048,8 @@ 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/gh-515-aggregate-temporary-lifetime.txt

@@ -0,0 +1,18 @@
+[GH #515]
+Lifetime of temporaries in aggregate initialization
+
+In C++, a temporary created in the initializer of an element of an aggregate
+was destroyed at the end of that element's initialization in some contexts
+(e.g., in the initializer of a variable, a mem-initializer, or a default
+member initializer), instead of when the initialization of the whole
+aggregate is complete.  It is now destroyed at the end of the complete
+initialization, including for nested aggregate initializers.  When emulating
+GCC versions before 12 or MSVC, which destroy such temporaries at the end of
+each element in the initializer of a variable, that behavior is kept for
+variables.  For example:
+
+  struct Temp { Temp(); ~Temp(); };
+  struct A { A(const Temp&); };
+  struct Pair { A a; int b; };
+  int f();
+  Pair p{A(Temp{}), f()};  // The Temp is now still alive when f is called.

tests/expectations/edg_x86_64/imported.log

@@ -6644,7 +6644,6 @@ gnu/cpp/cpp0x/initlist-opt2.sft.cpp:fp:-DTEST_NUMBER=1 --c++11:FAIL:
 gnu/cpp/cpp0x/initlist-ref1.sft.cpp:fp:-DTEST_NUMBER=1 --c++11:FAIL:
 gnu/cpp/cpp0x/initlist-ref3.sft.cpp:fp:-DTEST_NUMBER=1 --c++11:FAIL:
 gnu/cpp/cpp0x/initlist-value4.sft.cpp:fn:-DTEST_NUMBER=1 --c++11:FAIL:
-gnu/cpp/cpp0x/initlist122.sft.cpp:rp:-DTEST_NUMBER=1 --c++11:FAIL:
 gnu/cpp/cpp0x/initlist13.sft.cpp:fp:-DTEST_NUMBER=1 --c++11:FAIL:
 gnu/cpp/cpp0x/initlist36.sft.cpp:fn:-DTEST_NUMBER=1 --c++11:FAIL:
 gnu/cpp/cpp0x/initlist55.sft.cpp:s:-DTEST_NUMBER=1 --c++11 -W:SKIPPED:
@@ -7721,10 +7720,8 @@ gnu/cpp/inherit/pr97268.sft.cpp:fn:-DTEST_NUMBER=1 --c++11:FAIL:
 gnu/cpp/inherit/using4.sft.cpp:fn:-DTEST_NUMBER=1:FAIL:
 gnu/cpp/init/addr-const1.sft.cpp:rp:-DTEST_NUMBER=1:FAIL:
 gnu/cpp/init/aggr4.sft.cpp:fn:-DTEST_NUMBER=1 --c++11:FAIL:
-gnu/cpp/init/aggr7-eh.sft.cpp:rp:-DTEST_NUMBER=1:FAIL:
 gnu/cpp/init/aggr7-eh2.sft.cpp:rp:-DTEST_NUMBER=1:FAIL:
 gnu/cpp/init/aggr7-eh3.sft.cpp:rp:-DTEST_NUMBER=1:FAIL:
-gnu/cpp/init/array12.sft.cpp:rp:-DTEST_NUMBER=1:FAIL:
 gnu/cpp/init/array44.sft.cpp:fn:-DTEST_NUMBER=1:FAIL:
 gnu/cpp/init/brace4.sft.cpp:fn:-DTEST_NUMBER=1:FAIL:
 gnu/cpp/init/copy3.sft.cpp:rp:-DTEST_NUMBER=1 --c++14:FAIL:

tests/tests/cwg/.cwg3100.rto/default.1.2.txt

@@ -1,6 +1,6 @@
 ./a.out
+~DTemp
 ~A
 ~A
 ~BTemp
-~DTemp
 ~BTemp

tests/tests/imported/clang/cpp/SemaCXX/.source_location.rto/default.1.1.txt

@@ -135,80 +135,6 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
       check(t.x, "   T", 0);
            ^
 
-"test_passed.cpp", line 4301: error: static assertion failed with ""
-  static_assert(b.a.n == 4300, "");
-  ^
-"test_passed.cpp", line 4301: note: the final comparison was 4201 == 4300
-  static_assert(b.a.n == 4300, "");
-                      ^
-
-"test_passed.cpp", line 4302: error: static assertion failed with ""
-  static_assert(b.a.n2 == 4300, "");
-  ^
-"test_passed.cpp", line 4302: note: the final comparison was 4201 == 4300
-  static_assert(b.a.n2 == 4300, "");
-                       ^
-
-"test_passed.cpp", line 4303: error: static assertion failed with ""
-  static_assert(b.a.info.line() == 4300, "");
-  ^
-"test_passed.cpp", line 4303: note: the final comparison was 4201 == 4300
-  static_assert(b.a.info.line() == 4300, "");
-                                ^
-
-"test_passed.cpp", line 4304: error: static assertion failed
-  static_assert(is_equal(b.a.f, "test_passed.cpp"));
-  ^
-
-"test_passed.cpp", line 4305: error: static assertion failed
-  static_assert(is_equal(b.a.f2, "test_passed.cpp"));
-  ^
-
-"test_passed.cpp", line 4306: error: static assertion failed
-  static_assert(is_equal(b.a.info.file(), "test_passed.cpp"));
-  ^
-
-"test_func_passed.cpp", line 4401: error: static assertion failed with ""
-    static_assert(b.a.n == 4400, "");
-    ^
-"test_func_passed.cpp", line 4401: note: the final comparison was 4201 == 4400
-    static_assert(b.a.n == 4400, "");
-                        ^
-
-"test_func_passed.cpp", line 4402: error: static assertion failed with ""
-    static_assert(b.a.n2 == 4400, "");
-    ^
-"test_func_passed.cpp", line 4402: note: the final comparison was 4201 == 4400
-    static_assert(b.a.n2 == 4400, "");
-                         ^
-
-"test_func_passed.cpp", line 4403: error: static assertion failed with ""
-    static_assert(b.a.info.line() == 4400, "");
-    ^
-"test_func_passed.cpp", line 4403: note: the final comparison was 4201 == 4400
-    static_assert(b.a.info.line() == 4400, "");
-                                  ^
-
-"test_func_passed.cpp", line 4404: error: static assertion failed
-    static_assert(is_equal(b.a.f, "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4405: error: static assertion failed
-    static_assert(is_equal(b.a.f2, "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4406: error: static assertion failed
-    static_assert(is_equal(b.a.info.file(), "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4407: error: static assertion failed
-    static_assert(is_equal(b.a.func, "test_in_func"));
-    ^
-
-"test_func_passed.cpp", line 4408: error: static assertion failed
-    static_assert(is_equal(b.a.func2, "test_in_func"));
-    ^
-
 "test_func_passed.cpp", line 4409: error: static assertion failed
     static_assert(is_equal(b.a.info.function(), "bool test_out_of_line_init::test_in_func()"));
     ^
@@ -239,4 +165,4 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
     ^
           detected during instantiation of "Pair<U, U> test_func::test_func_template(T, U) [with T=int, U=SL]" at line 361
 
-39 errors detected in the compilation of "Test_name.c".
+25 errors detected in the compilation of "Test_name.c".

tests/tests/imported/clang/cpp/SemaCXX/.source_location.rto/default.10.1.txt

@@ -145,80 +145,6 @@ fe_only -DTEST_NUMBER=10 --clang -tused -e 200 --no_wrap_diagnostics --clang_ver
       check(t.x, "   T", 0);
            ^
 
-"test_passed.cpp", line 4301: error: static assertion failed with ""
-  static_assert(b.a.n == 4300, "");
-  ^
-"test_passed.cpp", line 4301: note: the final comparison was 4201 == 4300
-  static_assert(b.a.n == 4300, "");
-                      ^
-
-"test_passed.cpp", line 4302: error: static assertion failed with ""
-  static_assert(b.a.n2 == 4300, "");
-  ^
-"test_passed.cpp", line 4302: note: the final comparison was 4201 == 4300
-  static_assert(b.a.n2 == 4300, "");
-                       ^
-
-"test_passed.cpp", line 4303: error: static assertion failed with ""
-  static_assert(b.a.info.line() == 4300, "");
-  ^
-"test_passed.cpp", line 4303: note: the final comparison was 4201 == 4300
-  static_assert(b.a.info.line() == 4300, "");
-                                ^
-
-"test_passed.cpp", line 4304: error: static assertion failed
-  static_assert(is_equal(b.a.f, "test_passed.cpp"));
-  ^
-
-"test_passed.cpp", line 4305: error: static assertion failed
-  static_assert(is_equal(b.a.f2, "test_passed.cpp"));
-  ^
-
-"test_passed.cpp", line 4306: error: static assertion failed
-  static_assert(is_equal(b.a.info.file(), "test_passed.cpp"));
-  ^
-
-"test_func_passed.cpp", line 4401: error: static assertion failed with ""
-    static_assert(b.a.n == 4400, "");
-    ^
-"test_func_passed.cpp", line 4401: note: the final comparison was 4201 == 4400
-    static_assert(b.a.n == 4400, "");
-                        ^
-
-"test_func_passed.cpp", line 4402: error: static assertion failed with ""
-    static_assert(b.a.n2 == 4400, "");
-    ^
-"test_func_passed.cpp", line 4402: note: the final comparison was 4201 == 4400
-    static_assert(b.a.n2 == 4400, "");
-                         ^
-
-"test_func_passed.cpp", line 4403: error: static assertion failed with ""
-    static_assert(b.a.info.line() == 4400, "");
-    ^
-"test_func_passed.cpp", line 4403: note: the final comparison was 4201 == 4400
-    static_assert(b.a.info.line() == 4400, "");
-                                  ^
-
-"test_func_passed.cpp", line 4404: error: static assertion failed
-    static_assert(is_equal(b.a.f, "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4405: error: static assertion failed
-    static_assert(is_equal(b.a.f2, "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4406: error: static assertion failed
-    static_assert(is_equal(b.a.info.file(), "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4407: error: static assertion failed
-    static_assert(is_equal(b.a.func, "test_in_func"));
-    ^
-
-"test_func_passed.cpp", line 4408: error: static assertion failed
-    static_assert(is_equal(b.a.func2, "test_in_func"));
-    ^
-
 "test_func_passed.cpp", line 4409: error: static assertion failed
     static_assert(is_equal(b.a.info.function(), "bool test_out_of_line_init::test_in_func()"));
     ^
@@ -286,4 +212,4 @@ fe_only -DTEST_NUMBER=10 --clang -tused -e 200 --no_wrap_diagnostics --clang_ver
         ^
           detected during instantiation of "void test_func::inner::C<Ty>::df<T>(double) [with Ty=test_func::A, T=void]" at line 496
 
-47 errors detected in the compilation of "Test_name.c".
+33 errors detected in the compilation of "Test_name.c".

tests/tests/imported/clang/cpp/SemaCXX/.source_location.rto/default.2.1.txt

@@ -135,80 +135,6 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
       check(t.x, "   T", 0);
            ^
 
-"test_passed.cpp", line 4301: error: static assertion failed with ""
-  static_assert(b.a.n == 4300, "");
-  ^
-"test_passed.cpp", line 4301: note: the final comparison was 4201 == 4300
-  static_assert(b.a.n == 4300, "");
-                      ^
-
-"test_passed.cpp", line 4302: error: static assertion failed with ""
-  static_assert(b.a.n2 == 4300, "");
-  ^
-"test_passed.cpp", line 4302: note: the final comparison was 4201 == 4300
-  static_assert(b.a.n2 == 4300, "");
-                       ^
-
-"test_passed.cpp", line 4303: error: static assertion failed with ""
-  static_assert(b.a.info.line() == 4300, "");
-  ^
-"test_passed.cpp", line 4303: note: the final comparison was 4201 == 4300
-  static_assert(b.a.info.line() == 4300, "");
-                                ^
-
-"test_passed.cpp", line 4304: error: static assertion failed
-  static_assert(is_equal(b.a.f, "test_passed.cpp"));
-  ^
-
-"test_passed.cpp", line 4305: error: static assertion failed
-  static_assert(is_equal(b.a.f2, "test_passed.cpp"));
-  ^
-
-"test_passed.cpp", line 4306: error: static assertion failed
-  static_assert(is_equal(b.a.info.file(), "test_passed.cpp"));
-  ^
-
-"test_func_passed.cpp", line 4401: error: static assertion failed with ""
-    static_assert(b.a.n == 4400, "");
-    ^
-"test_func_passed.cpp", line 4401: note: the final comparison was 4201 == 4400
-    static_assert(b.a.n == 4400, "");
-                        ^
-
-"test_func_passed.cpp", line 4402: error: static assertion failed with ""
-    static_assert(b.a.n2 == 4400, "");
-    ^
-"test_func_passed.cpp", line 4402: note: the final comparison was 4201 == 4400
-    static_assert(b.a.n2 == 4400, "");
-                         ^
-
-"test_func_passed.cpp", line 4403: error: static assertion failed with ""
-    static_assert(b.a.info.line() == 4400, "");
-    ^
-"test_func_passed.cpp", line 4403: note: the final comparison was 4201 == 4400
-    static_assert(b.a.info.line() == 4400, "");
-                                  ^
-
-"test_func_passed.cpp", line 4404: error: static assertion failed
-    static_assert(is_equal(b.a.f, "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4405: error: static assertion failed
-    static_assert(is_equal(b.a.f2, "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4406: error: static assertion failed
-    static_assert(is_equal(b.a.info.file(), "test_func_passed.cpp"));
-    ^
-
-"test_func_passed.cpp", line 4407: error: static assertion failed
-    static_assert(is_equal(b.a.func, "test_in_func"));
-    ^
-
-"test_func_passed.cpp", line 4408: error: static assertion failed
-    static_assert(is_equal(b.a.func2, "test_in_func"));
-    ^
-
 "test_func_passed.cpp", line 4409: error: static assertion failed
     static_assert(is_equal(b.a.info.function(), "bool test_out_of_line_init::test_in_func()"));
     ^
@@ -239,4 +165,4 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
     ^
           detected during instantiation of "Pair<U, U> test_func::test_func_template(T, U) [with T=int, U=SL]" at line 361
 
-39 errors detected in the compilation of "Test_name.c".
+25 errors detected in the compilation of "Test_name.c".