PR c++/86094 - wrong code with defaulted move ctor.

gcc/c-family/
	* c-opts.c (c_common_post_options): Bump the current ABI version to
	13.  Set warn_abi_version and flag_abi_compat_version to the current
	version rather than 0.  Fix defaulting flag_abi_compat_version from
	warn_abi_version.
gcc/cp/
	* class.c (classtype_has_non_deleted_move_ctor): New.
	* tree.c (maybe_warn_parm_abi, type_has_nontrivial_copy_init):
	Handle v12 breakage.

From-SVN: r261562

gcc/c-family/ChangeLog

@@ -1,3 +1,11 @@
+2018-06-13  Jason Merrill  <jason@redhat.com>
+
+	PR c++/86094 - wrong code with defaulted move ctor.
+	* c-opts.c (c_common_post_options): Bump the current ABI version to
+	13.  Set warn_abi_version and flag_abi_compat_version to the current
+	version rather than 0.  Fix defaulting flag_abi_compat_version from
+	warn_abi_version.
+
 2018-06-12  Martin Sebor  <msebor@redhat.com>
 
 	PR c/85931

gcc/c-family/c-opts.c

@@ -915,30 +915,37 @@ c_common_post_options (const char **pfilename)
   if (flag_declone_ctor_dtor == -1)
     flag_declone_ctor_dtor = optimize_size;
 
-  if (warn_abi_version == -1)
-    {
-      if (flag_abi_compat_version != -1)
-	warn_abi_version = flag_abi_compat_version;
-      else
-	warn_abi_version = 0;
-    }
-
   if (flag_abi_compat_version == 1)
     {
       warning (0, "%<-fabi-compat-version=1%> is not supported, using =2");
       flag_abi_compat_version = 2;
     }
-  else if (flag_abi_compat_version == -1)
-    {
-      /* Generate compatibility aliases for ABI v11 (7.1) by default. */
-      flag_abi_compat_version
-	= (flag_abi_version == 0 ? 11 : 0);
-    }
 
-  /* Change flag_abi_version to be the actual current ABI level for the
-     benefit of c_cpp_builtins.  */
-  if (flag_abi_version == 0)
-    flag_abi_version = 12;
+  /* Change flag_abi_version to be the actual current ABI level, for the
+     benefit of c_cpp_builtins, and to make comparison simpler.  */
+  const int latest_abi_version = 13;
+  /* Generate compatibility aliases for ABI v11 (7.1) by default.  */
+  const int abi_compat_default = 11;
+
+#define clamp(X) if (X == 0 || X > latest_abi_version) X = latest_abi_version
+  clamp (flag_abi_version);
+  clamp (warn_abi_version);
+  clamp (flag_abi_compat_version);
+#undef clamp
+
+  /* Default -Wabi= or -fabi-compat-version= from each other.  */
+  if (warn_abi_version == -1 && flag_abi_compat_version != -1)
+    warn_abi_version = flag_abi_compat_version;
+  else if (flag_abi_compat_version == -1 && warn_abi_version != -1)
+    flag_abi_compat_version = warn_abi_version;
+  else if (warn_abi_version == -1 && flag_abi_compat_version == -1)
+    {
+      warn_abi_version = latest_abi_version;
+      if (flag_abi_version == latest_abi_version)
+	flag_abi_compat_version = abi_compat_default;
+      else
+	flag_abi_compat_version = latest_abi_version;
+    }
 
   /* By default, enable the new inheriting constructor semantics along with ABI
      11.  New and old should coexist fine, but it is a change in what

gcc/common.opt

@@ -938,7 +938,11 @@ Driver Undocumented
 ;
 ; 12: Corrects the calling convention for classes with only deleted copy/move
 ;     constructors and changes passing/returning of empty records.
-;     Default in G++ 8.
+;     Default in G++ 8.1.
+;
+; 13: Fixes the accidental change in 12 to the calling convention for classes
+;     with deleted copy constructor and trivial move constructor.
+;     Default in G++ 8.2.
 ;
 ; Additional positive integers will be assigned as new versions of
 ; the ABI become the default version of the ABI.

gcc/cp/ChangeLog

@@ -1,3 +1,10 @@
+2018-06-13  Jason Merrill  <jason@redhat.com>
+
+	PR c++/86094 - wrong code with defaulted move ctor.
+	* class.c (classtype_has_non_deleted_move_ctor): New.
+	* tree.c (maybe_warn_parm_abi, type_has_nontrivial_copy_init):
+	Handle v12 breakage.
+
 2018-06-12  Jason Merrill  <jason@redhat.com>
 
 	PR c++/86098 - ICE with template placeholder for TTP.

gcc/cp/class.c

@@ -5175,6 +5175,19 @@ classtype_has_move_assign_or_move_ctor_p (tree t, bool user_p)
   return false;
 }
 
+/* True iff T has a move constructor that is not deleted.  */
+
+bool
+classtype_has_non_deleted_move_ctor (tree t)
+{
+  if (CLASSTYPE_LAZY_MOVE_CTOR (t))
+    lazily_declare_fn (sfk_move_constructor, t);
+  for (ovl_iterator iter (CLASSTYPE_CONSTRUCTORS (t)); iter; ++iter)
+    if (move_fn_p (*iter) && !DECL_DELETED_FN (*iter))
+      return true;
+  return false;
+}
+
 /* If T, a class, has a user-provided copy constructor, copy assignment
    operator, or destructor, returns that function.  Otherwise, null.  */
 

gcc/cp/cp-tree.h

@@ -6163,6 +6163,7 @@ extern bool trivial_default_constructor_is_constexpr (tree);
 extern bool type_has_constexpr_default_constructor (tree);
 extern bool type_has_virtual_destructor		(tree);
 extern bool classtype_has_move_assign_or_move_ctor_p (tree, bool user_declared);
+extern bool classtype_has_non_deleted_move_ctor (tree);
 extern tree classtype_has_user_copy_or_dtor	(tree);
 extern bool type_build_ctor_call		(tree);
 extern bool type_build_dtor_call		(tree);

gcc/cp/tree.c

@@ -4071,8 +4071,21 @@ maybe_warn_parm_abi (tree t, location_t loc)
       || !deleted_copy_types->contains (t))
     return;
 
+  if ((flag_abi_version == 12 || warn_abi_version == 12)
+      && classtype_has_non_deleted_move_ctor (t))
+    {
+      if (flag_abi_version > 12)
+	warning_at (loc, OPT_Wabi, "-fabi-version=13 (GCC 8.2) fixes the "
+		    "calling convention for %qT, which was accidentally "
+		    "changed in 8.1", t);
+      else
+	warning_at (loc, OPT_Wabi, "-fabi-version=12 (GCC 8.1) accidentally "
+		    "changes the calling convention for %qT", t);
+      return;
+    }
+
   warning_at (loc, OPT_Wabi, "the calling convention for %qT changes in "
-	      "-fabi-version=12 (GCC 8)", t);
+	      "-fabi-version=13 (GCC 8.2)", t);
   static bool explained = false;
   if (!explained)
     {
@@ -4114,6 +4127,7 @@ type_has_nontrivial_copy_init (const_tree type)
 
       bool saw_copy = false;
       bool saw_non_deleted = false;
+      bool saw_non_deleted_move = false;
 
       if (CLASSTYPE_LAZY_MOVE_CTOR (t))
 	saw_copy = saw_non_deleted = true;
@@ -4135,7 +4149,7 @@ type_has_nontrivial_copy_init (const_tree type)
 	for (ovl_iterator iter (CLASSTYPE_CONSTRUCTORS (t)); iter; ++iter)
 	  {
 	    tree fn = *iter;
-	    if (copy_fn_p (fn) || move_fn_p (fn))
+	    if (copy_fn_p (fn))
 	      {
 		saw_copy = true;
 		if (!DECL_DELETED_FN (fn))
@@ -4145,19 +4159,27 @@ type_has_nontrivial_copy_init (const_tree type)
 		    break;
 		  }
 	      }
+	    else if (move_fn_p (fn))
+	      if (!DECL_DELETED_FN (fn))
+		saw_non_deleted_move = true;
 	  }
 
       gcc_assert (saw_copy);
 
-      if (saw_copy && !saw_non_deleted)
-	{
-	  if (warn_abi && abi_version_crosses (12))
-	    remember_deleted_copy (t);
-	  if (abi_version_at_least (12))
-	    return true;
-	}
+      /* ABI v12 buggily ignored move constructors.  */
+      bool v11nontriv = false;
+      bool v12nontriv = !saw_non_deleted;
+      bool v13nontriv = !saw_non_deleted && !saw_non_deleted_move;
+      bool nontriv = (abi_version_at_least (13) ? v13nontriv
+		      : flag_abi_version == 12 ? v12nontriv
+		      : v11nontriv);
+      bool warn_nontriv = (warn_abi_version >= 13 ? v13nontriv
+			   : warn_abi_version == 12 ? v12nontriv
+			   : v11nontriv);
+      if (nontriv != warn_nontriv)
+	remember_deleted_copy (t);
 
-      return false;
+      return nontriv;
     }
   else
     return 0;

gcc/doc/invoke.texi

@@ -2348,7 +2348,12 @@ implies @option{-fnew-inheriting-ctors}.
 
 Version 12, which first appeared in G++ 8, corrects the calling
 conventions for empty classes on the x86_64 target and for classes
-with only deleted copy/move constructors.
+with only deleted copy/move constructors.  It accidentally changes the
+calling convention for classes with a deleted copy constructor and a
+trivial move constructor.
+
+Version 13, which first appeared in G++ 8.2, fixes the accidental
+change in version 12.
 
 See also @option{-Wabi}.
 
@@ -2359,7 +2364,7 @@ works around mangling changes by creating an alias with the correct
 mangled name when defining a symbol with an incorrect mangled name.
 This switch specifies which ABI version to use for the alias.
 
-With @option{-fabi-version=0} (the default), this defaults to 8 (GCC 5
+With @option{-fabi-version=0} (the default), this defaults to 11 (GCC 7
 compatibility).  If another ABI version is explicitly selected, this
 defaults to 0.  For compatibility with GCC versions 3.2 through 4.9,
 use @option{-fabi-compat-version=2}.

gcc/testsuite/g++.dg/abi/invisiref2a.C

@@ -0,0 +1,14 @@
+// PR c++/86094
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-fabi-version=12 -Wabi -fdump-tree-gimple" }
+// { dg-final { scan-tree-dump "struct S &" "gimple" } }
+
+struct S {
+  S(S&&) = default;
+  int i;
+};
+
+S foo(S s)			// { dg-warning "calling convention" }
+{
+  return s;
+}

gcc/testsuite/g++.dg/abi/macro0.C

@@ -1,6 +1,6 @@
 // This testcase will need to be kept in sync with c_common_post_options.
 // { dg-options "-fabi-version=0" }
 
-#if __GXX_ABI_VERSION != 1012
+#if __GXX_ABI_VERSION != 1013
 #error "Incorrect value of __GXX_ABI_VERSION"
 #endif