From f8c1f29a0b47b4b4a3c1506678f7ca2ce4b7ffbb Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Fri, 25 Mar 2022 17:46:07 -0400 Subject: [PATCH] c++: ICE with aggregate assignment and DMI [PR104583] The attached 93280 test no longer ICEs but looks like it was never added to the testsuite. The 104583 test, modified so that it closely resembles 93280, still ICEs. The problem is that in 104583 we have a value-init from {} (the line A a{};), so this code in convert_like_internal 7960 /* If we're initializing from {}, it's value-initialization. */ 7961 if (BRACE_ENCLOSED_INITIALIZER_P (expr) 7962 && CONSTRUCTOR_NELTS (expr) == 0 7963 && TYPE_HAS_DEFAULT_CONSTRUCTOR (totype) 7964 && !processing_template_decl) 7965 { 7966 bool direct = CONSTRUCTOR_IS_DIRECT_INIT (expr); ... 7974 TARGET_EXPR_DIRECT_INIT_P (expr) = direct; sets TARGET_EXPR_DIRECT_INIT_P. This does not happen in 93280 where we initialize from {0}. In 104583, when gimplifying, the d = {}; line, we have d = {.a=TARGET_EXPR >> >>>>} where the TARGET_EXPR is the one with TARGET_EXPR_DIRECT_INIT_P set. In gimplify_init_ctor_preeval we do 4724 FOR_EACH_VEC_SAFE_ELT (v, ix, ce) 4725 gimplify_init_ctor_preeval (&ce->value, pre_p, post_p, data); so we gimplify the TARGET_EXPR, crashing at 744 case TARGET_EXPR: 745 /* A TARGET_EXPR that expresses direct-initialization should have been 746 elided by cp_gimplify_init_expr. */ 747 gcc_checking_assert (!TARGET_EXPR_DIRECT_INIT_P (*expr_p)); but there is no INIT_EXPR so cp_gimplify_init_expr was never called! Now, the fix for c++/93280 says "let's only set TARGET_EXPR_DIRECT_INIT_P when we're using the DMI in a constructor." and the comment talks about the full initialization. Is is accurate to say that our TARGET_EXPR does not represent the full initialization, because it only initializes the 'a' subobject? If so, then maybe get_nsdmi should clear TARGET_EXPR_DIRECT_INIT_P when in_ctor is false. I've compared the 93280.s and 104583.s files, they differ only in one movl $0, so there are no extra calls and similar. PR c++/93280 PR c++/104583 gcc/cp/ChangeLog: * init.cc (get_nsdmi): Set TARGET_EXPR_DIRECT_INIT_P to in_ctor. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/nsdmi-list7.C: New test. * g++.dg/cpp0x/nsdmi-list8.C: New test. --- gcc/cp/init.cc | 8 ++++---- gcc/testsuite/g++.dg/cpp0x/nsdmi-list7.C | 17 +++++++++++++++++ gcc/testsuite/g++.dg/cpp0x/nsdmi-list8.C | 17 +++++++++++++++++ 3 files changed, 38 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-list7.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-list8.C diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc index 91b5c2c..01e7623 100644 --- a/gcc/cp/init.cc +++ b/gcc/cp/init.cc @@ -679,10 +679,10 @@ get_nsdmi (tree member, bool in_ctor, tsubst_flags_t complain) if (simple_target) init = TARGET_EXPR_INITIAL (init); init = break_out_target_exprs (init, /*loc*/true); - if (in_ctor && init && TREE_CODE (init) == TARGET_EXPR) - /* This expresses the full initialization, prevent perform_member_init from - calling another constructor (58162). */ - TARGET_EXPR_DIRECT_INIT_P (init) = true; + if (init && TREE_CODE (init) == TARGET_EXPR) + /* In a constructor, this expresses the full initialization, prevent + perform_member_init from calling another constructor (58162). */ + TARGET_EXPR_DIRECT_INIT_P (init) = in_ctor; if (simple_target && TREE_CODE (init) != CONSTRUCTOR) /* Now put it back so C++17 copy elision works. */ init = get_target_expr (init); diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-list7.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-list7.C new file mode 100644 index 0000000..62b0742 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-list7.C @@ -0,0 +1,17 @@ +// PR c++/93280 +// { dg-do compile { target c++11 } } + +struct A { + template A(T); + int c; +}; + +struct D { + A a{0}; +}; + +void g() +{ + D d; + d = {}; +} diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-list8.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-list8.C new file mode 100644 index 0000000..fe73da8 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-list8.C @@ -0,0 +1,17 @@ +// PR c++/104583 +// { dg-do compile { target c++11 } } + +struct A { + A(); + int c; +}; + +struct D { + A a{}; +}; + +void g() +{ + D d; + d = {}; +} -- 2.7.4