* doc/invoke.texi (C++ Dialect Options): Document -Wno-narrowing.

From-SVN: r176670

gcc/ChangeLog

+2011-07-22  Jason Merrill  <jason@redhat.com>
+
+	* doc/invoke.texi (C++ Dialect Options): Document -Wno-narrowing.
+
 2011-07-22  Richard Henderson  <rth@redhat.com>
 
 	* bb-reorder.c (gate_handle_partition_blocks): Honor optimize.

gcc/doc/invoke.texi

@@ -2348,6 +2348,18 @@ an instance of a derived class through a pointer to a base class if the
 base class does not have a virtual destructor.  This warning is enabled
 by @option{-Wall}.
 
+@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
+@opindex Wnarrowing
+@opindex Wno-narrowing
+With -std=c++0x, suppress the diagnostic required by the standard for
+narrowing conversions within @samp{@{ @}}, e.g.
+
+@smallexample
+int i = @{ 2.2 @}; // error: narrowing from double to int
+@end smallexample
+
+This flag can be useful for compiling valid C++98 code in C++0x mode.
+
 @item -Wnoexcept @r{(C++ and Objective-C++ only)}
 @opindex Wnoexcept
 @opindex Wno-noexcept

gcc/testsuite/g++.dg/cpp0x/initlist55.C

+// Test for -Wno-narrowing
+// { dg-options "-std=c++0x -pedantic-errors -Wno-narrowing" }
+
+int i;
+float d = { i };