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C++ PATCH for c++/60417 (explicit ctor vs aggregate init)

Message ID 5316505A.1010901@redhat.com
State New
Headers show

Commit Message

Jason Merrill March 4, 2014, 10:14 p.m. UTC 
In C++11, copy-list-initialization by explicit constructor is an error, 
even for the default constructor.  But this combined with the change of 
aggregate initialization to use {} for any missing initializers means 
that well-formed C++03 code becomes ill-formed in C++11.  Until the 
committee decides what to do about this, let's call the implicit 
initializers direct-initialization.

Tested x86_64-pc-linux-gnu, applying to trunk.
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Patch

commit ea0a530e2164b029909934a1cd4985f8c2bc3b00
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Mar 4 16:16:36 2014 -0500

    	PR c++/60417
    	* typeck2.c (process_init_constructor_record): Set
    	CONSTRUCTOR_IS_DIRECT_INIT on {} for omitted initializers.

diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 8877286..3a4caa0 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -1312,6 +1312,9 @@  process_init_constructor_record (tree type, tree init,
 	     for us, so build up TARGET_EXPRs.  If the type in question is
 	     a class, just build one up; if it's an array, recurse.  */
 	  next = build_constructor (init_list_type_node, NULL);
+	  /* Call this direct-initialization pending DR 1518 resolution so
+	     that explicit default ctors don't break valid C++03 code.  */
+	  CONSTRUCTOR_IS_DIRECT_INIT (next) = true;
 	  next = massage_init_elt (TREE_TYPE (field), next, complain);
 
 	  /* Warn when some struct elements are implicitly initialized.  */
diff --git a/gcc/testsuite/g++.dg/init/explicit1.C b/gcc/testsuite/g++.dg/init/explicit1.C
new file mode 100644
index 0000000..f376df2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/explicit1.C
@@ -0,0 +1,9 @@ 
+// PR c++/60417
+
+struct A { explicit A(int = 0); };
+struct B { A a; };
+
+int main()
+{
+  B b = {};
+}