re PR c++/50810 (c++0x-compat does not warn about narrowing conversions)

/c-family
2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/50810
	* c-opts.c (c_common_handle_option): Enable -Wnarrowing as part
	of -Wall; include -Wnarrowing in -Wc++0x-compat; adjust default
	Wnarrowing for C++0x and C++98.
	* c.opt ([Wnarrowing]): Update.

/cp
2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/50810
	* typeck2.c (check_narrowing): Adjust OPT_Wnarrowing diagnostics.
	(digest_init_r): Call check_narrowing irrespective of the C++ dialect.
	* decl.c (check_initializer): Likewise.
	* semantics.c (finish_compound_literal): Likewise.

/testsuite
2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/50810
	* g++.dg/cpp0x/warn_cxx0x2.C: New.
	* g++.dg/cpp0x/warn_cxx0x3.C: Likewise.

2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/50810
	* doc/invoke.texi ([-Wnarrowing], [-Wc++0x-compat]): Update.

From-SVN: r180343

12 files changed, 66 insertions, 15 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 525ced5..0c884cc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/50810
+	* doc/invoke.texi ([-Wnarrowing], [-Wc++0x-compat]): Update.
+
 2011-10-23  Tom de Vries  <tom@codesourcery.com>
 
 	PR tree-optimization/50763
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 706b273..9cd0b83 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,11 @@
+2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/50810
+	* c-opts.c (c_common_handle_option): Enable -Wnarrowing as part
+	of -Wall; include -Wnarrowing in -Wc++0x-compat; adjust default
+	Wnarrowing for C++0x and C++98.
+	* c.opt ([Wnarrowing]): Update.
+
 2011-10-21  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/45385
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index 6869d5c..14e4933 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -406,6 +406,7 @@ c_common_handle_option (size_t scode, const char *arg, int value,
 	  warn_reorder = value;
           warn_cxx0x_compat = value;
           warn_delnonvdtor = value;
+	  warn_narrowing = value;
 	}
 
       cpp_opts->warn_trigraphs = value;
@@ -436,6 +437,10 @@ c_common_handle_option (size_t scode, const char *arg, int value,
       cpp_opts->warn_cxx_operator_names = value;
       break;
 
+    case OPT_Wc__0x_compat:
+      warn_narrowing = value;
+      break;
+
     case OPT_Wdeprecated:
       cpp_opts->cpp_warn_deprecated = value;
       break;
@@ -997,10 +1002,17 @@ c_common_post_options (const char **pfilename)
   if (warn_implicit_function_declaration == -1)
     warn_implicit_function_declaration = flag_isoc99;
 
-  /* If we're allowing C++0x constructs, don't warn about C++0x
-     compatibility problems.  */
   if (cxx_dialect == cxx0x)
-    warn_cxx0x_compat = 0;
+    {
+      /* If we're allowing C++0x constructs, don't warn about C++98
+	 identifiers which are keywords in C++0x.  */
+      warn_cxx0x_compat = 0;
+
+      if (warn_narrowing == -1)
+	warn_narrowing = 1;
+    }
+  else if (warn_narrowing == -1)
+    warn_narrowing = 0;
 
   if (flag_preprocess_only)
     {
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index bfc1a7c..0b9e44a 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -490,8 +490,8 @@ C ObjC C++ ObjC++ Warning
 Warn about use of multi-character character constants
 
 Wnarrowing
-C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(1)
--Wno-narrowing	  In C++0x mode, ignore ill-formed narrowing conversions within { }
+C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(-1) Warning
+Warn about ill-formed narrowing conversions within { }
 
 Wnested-externs
 C ObjC Var(warn_nested_externs) Warning
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index f3eea05..de5fab9 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/50810
+	* typeck2.c (check_narrowing): Adjust OPT_Wnarrowing diagnostics.
+	(digest_init_r): Call check_narrowing irrespective of the C++ dialect.
+	* decl.c (check_initializer): Likewise.
+	* semantics.c (finish_compound_literal): Likewise.
+
 2011-10-21  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/45385
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index a21cf46..f1ecca2 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -5523,7 +5523,7 @@ check_initializer (tree decl, tree init, int flags, tree *cleanup)
 	  else
 	    {
 	      init = reshape_init (type, init, tf_warning_or_error);
-	      if (cxx_dialect >= cxx0x && SCALAR_TYPE_P (type))
+	      if (SCALAR_TYPE_P (type))
 		check_narrowing (type, init);
 	    }
 	}
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 42195be..9fec334 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -2369,7 +2369,7 @@ finish_compound_literal (tree type, tree compound_literal,
       && check_array_initializer (NULL_TREE, type, compound_literal))
     return error_mark_node;
   compound_literal = reshape_init (type, compound_literal, complain);
-  if (cxx_dialect >= cxx0x && SCALAR_TYPE_P (type)
+  if (SCALAR_TYPE_P (type)
       && !BRACE_ENCLOSED_INITIALIZER_P (compound_literal))
     check_narrowing (type, compound_literal);
   if (TREE_CODE (type) == ARRAY_TYPE
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 0cb1104..76006b6 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -803,8 +803,10 @@ check_narrowing (tree type, tree init)
     }
 
   if (!ok)
-    pedwarn (input_location, OPT_Wnarrowing, "narrowing conversion of %qE "
-	     "from %qT to %qT inside { }", init, ftype, type);
+    emit_diagnostic ((cxx_dialect != cxx98) ? DK_PEDWARN : DK_WARNING,
+		     input_location, OPT_Wnarrowing,
+		     "narrowing conversion of %qE from %qT to %qT inside { }",
+		     init, ftype, type);
 }
 
 /* Process the initializer INIT for a variable of type TYPE, emitting
@@ -901,7 +903,7 @@ digest_init_r (tree type, tree init, bool nested, int flags,
     {
       tree *exp;
 
-      if (cxx_dialect != cxx98 && nested)
+      if (nested)
 	check_narrowing (type, init);
       init = convert_for_initialization (0, type, init, flags,
 					 ICR_INIT, NULL_TREE, 0,
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 09e115c..42f0651 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -2365,17 +2365,18 @@ 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)}
+@item -Wnarrowing @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.
+Warn when a narrowing conversion occurs 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.
+This flag is included in @option{-Wall} and @option{-Wc++0x-compat}.
+With -std=c++0x, @option{-Wno-narrowing} suppresses the diagnostic
+required by the standard.
 
 @item -Wnoexcept @r{(C++ and Objective-C++ only)}
 @opindex Wnoexcept
@@ -4066,7 +4067,8 @@ ISO C and ISO C++, e.g.@: request for implicit conversion from
 @item -Wc++0x-compat @r{(C++ and Objective-C++ only)}
 Warn about C++ constructs whose meaning differs between ISO C++ 1998 and
 ISO C++ 200x, e.g., identifiers in ISO C++ 1998 that will become keywords
-in ISO C++ 200x.  This warning is enabled by @option{-Wall}.
+in ISO C++ 200x.  This warning turns on @option{-Wnarrowing} and is
+enabled by @option{-Wall}.
 
 @item -Wcast-qual
 @opindex Wcast-qual
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b0c282d..036da06 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2011-10-23  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/50810
+	* g++.dg/cpp0x/warn_cxx0x2.C: New.
+	* g++.dg/cpp0x/warn_cxx0x3.C: Likewise.
+
 2011-10-23  Tom de Vries  <tom@codesourcery.com>
 
 	PR tree-optimization/50763
diff --git a/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x2.C b/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x2.C
new file mode 100644
index 0000000..1fc9c6b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x2.C
@@ -0,0 +1,4 @@
+// PR c++/50810
+// { dg-options "-std=gnu++98 -Wc++0x-compat" }
+
+signed char data[] = { 0xff }; // { dg-warning "narrowing" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x3.C b/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x3.C
new file mode 100644
index 0000000..91faf12
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x3.C
@@ -0,0 +1,4 @@
+// PR c++/50810
+// { dg-options "-std=gnu++98 -Wc++0x-compat -Wno-narrowing" }
+
+signed char data[] = { 0xff };