2015-09-15  Nathan Sidwell  <nathan@codesourcery.com>

	c-family/
	* c.opt (fmultiple-inheritance, fvirtual-inheritance, ftemplates,
	fnamespaces): New C++ options.

	cp/
	* decl.c (xref_basetypes): Check virtual and/or multiple
	inheritance not disabled.
	* parser.c (cp_parser_namespace_definition): Check namespaces
	not disabled.
	* pt.c (push_template_decl_real): Check templates not disabled.

	* doc/invoke.texi  (-fmultiple-inheritance, -fvirtual-inheritance,
	-ftemplates, -namespaces): Document.

	testsuite/
	* g++.dg/diagostic/disable.C: New.

Index: c-family/c.opt
===================================================================
--- c-family/c.opt	(revision 227761)
+++ c-family/c.opt	(working copy)
@@ -1257,9 +1257,17 @@ C ObjC C++ ObjC++ Ignore Warn(switch %qs
 fmudflapir
 C ObjC C++ ObjC++ Ignore Warn(switch %qs is no longer supported)
 
+fmultiple-inheritance
+C++ ObjC++ Var(flag_multiple_inheritance) Init(1)
+Enable multiple inheritance
+
 fname-mangling-version-
 C++ ObjC++ Joined Ignore Warn(switch %qs is no longer supported)
 
+fnamespaces
+C++ ObjC++ Var(flag_namespaces) Init(1)
+Enable namespaces
+
 fnew-abi
 C++ ObjC++ Ignore Warn(switch %qs is no longer supported)
 
@@ -1446,6 +1454,10 @@ ftabstop=
 C ObjC C++ ObjC++ Joined RejectNegative UInteger
 -ftabstop=<number>	Distance between tab stops for column reporting
 
+ftemplates
+C++ ObjC++ Var(flag_templates) Init(1)
+Enable templates
+
 ftemplate-backtrace-limit=
 C++ ObjC++ Joined RejectNegative UInteger Var(template_backtrace_limit) Init(10)
 Set the maximum number of template instantiation notes for a single warning or error
@@ -1480,6 +1492,10 @@ fuse-cxa-get-exception-ptr
 C++ ObjC++ Var(flag_use_cxa_get_exception_ptr) Init(2)
 Use __cxa_get_exception_ptr in exception handling
 
+fvirtual-inheritance
+C++ ObjC++ Var(flag_virtual_inheritance) Init(1)
+Enable virtual inheritance
+
 fvisibility-inlines-hidden
 C++ ObjC++
 Marks all inlined functions and methods as having hidden visibility
Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 227761)
+++ cp/decl.c	(working copy)
@@ -12814,6 +12814,9 @@ xref_basetypes (tree ref, tree base_list
 	  error ("Java class %qT cannot have multiple bases", ref);
           return false;
         }
+      else if (!flag_multiple_inheritance
+	       && !in_system_header_at (input_location))
+	error ("%qT defined with multiple bases", ref);
     }
 
   if (max_vbases)
@@ -12825,6 +12828,9 @@ xref_basetypes (tree ref, tree base_list
 	  error ("Java class %qT cannot have virtual bases", ref);
           return false;
         }
+      else if (!flag_virtual_inheritance
+	       && !in_system_header_at (input_location))
+	error ("%qT defined with virtual base", ref);
     }
 
   for (igo_prev = binfo; base_list; base_list = TREE_CHAIN (base_list))
Index: cp/parser.c
===================================================================
--- cp/parser.c	(revision 227761)
+++ cp/parser.c	(working copy)
@@ -16798,6 +16798,9 @@ cp_parser_namespace_definition (cp_parse
 
   has_visibility = handle_namespace_attrs (current_namespace, attribs);
 
+  if (!flag_namespaces && !in_system_header_at (input_location))
+    error  ("namepace %qD entered", current_namespace);
+
   /* Parse the body of the namespace.  */
   cp_parser_namespace_body (parser);
 
Index: cp/pt.c
===================================================================
--- cp/pt.c	(revision 227761)
+++ cp/pt.c	(working copy)
@@ -5088,6 +5088,9 @@ push_template_decl_real (tree decl, bool
 
   if (is_primary)
     {
+      if (!flag_templates && !in_system_header_at (input_location))
+	error ("template %qD declared", decl);
+
       if (DECL_CLASS_SCOPE_P (decl))
 	member_template_p = true;
       if (TREE_CODE (decl) == TYPE_DECL
Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi	(revision 227761)
+++ doc/invoke.texi	(working copy)
@@ -183,19 +183,19 @@ in the following sections.
 -ffor-scope  -fno-for-scope  -fno-gnu-keywords @gol
 -fno-implicit-templates @gol
 -fno-implicit-inline-templates @gol
--fno-implement-inlines  -fms-extensions @gol
--fno-nonansi-builtins  -fnothrow-opt  -fno-operator-names @gol
+-fno-implement-inlines  -fms-extensions -fno-multiple-inheritance &gol
+-fno-namespaces -fno-nonansi-builtins  -fnothrow-opt  -fno-operator-names @gol
 -fno-optional-diags  -fpermissive @gol
 -fno-pretty-templates @gol
 -frepo  -fno-rtti -fsized-deallocation @gol
 -fstats  -ftemplate-backtrace-limit=@var{n} @gol
--ftemplate-depth=@var{n} @gol
+-ftemplate-depth=@var{n} -fno-templates @gol
 -fno-threadsafe-statics  -fuse-cxa-atexit @gol
 -fno-weak  -nostdinc++ @gol
 -fvisibility-inlines-hidden @gol
 -fvtable-verify=@r{[}std@r{|}preinit@r{|}none@r{]} @gol
 -fvtv-counts -fvtv-debug @gol
--fvisibility-ms-compat @gol
+-fno-virtual-inheritance -fvisibility-ms-compat @gol
 -fext-numeric-literals @gol
 -Wabi=@var{n}  -Wabi-tag  -Wconversion-null  -Wctor-dtor-privacy @gol
 -Wdelete-non-virtual-dtor -Wliteral-suffix -Wnarrowing @gol
@@ -2292,6 +2292,14 @@ errors if these functions are not inline
 Disable Wpedantic warnings about constructs used in MFC, such as implicit
 int and getting a pointer to member function via non-standard syntax.
 
+@item -fno-multiple-inheritance
+@opindex fno-multiple-inheritance
+Do not permit multiple inheritance, except in system header files.
+
+@item -fno-namespaces
+@opindex fno-namespacess
+Do not permit namespace definitions, except in system header files.
+
 @item -fno-nonansi-builtins
 @opindex fno-nonansi-builtins
 Disable built-in declarations of functions that are not mandated by
@@ -2399,6 +2407,10 @@ conforming programs must not rely on a m
 (changed to 1024 in C++11).  The default value is 900, as the compiler
 can run out of stack space before hitting 1024 in some situations.
 
+@item -fno-templates
+@opindex fno-templates
+Do not permit primary template declarations, except in system header files.
+
 @item -fno-threadsafe-statics
 @opindex fno-threadsafe-statics
 Do not emit the extra code to use the routines specified in the C++
@@ -2420,6 +2432,10 @@ Don't use the @code{__cxa_get_exception_
 causes @code{std::uncaught_exception} to be incorrect, but is necessary
 if the runtime routine is not available.
 
+@item -fno-virtual-inheritance
+@opindex fno-virtual-inheritance
+Do not permit virtual inheritance, except in system header files.
+
 @item -fvisibility-inlines-hidden
 @opindex fvisibility-inlines-hidden
 This switch declares that the user does not attempt to compare
Index: testsuite/g++.dg/diagnostic/disable.C
===================================================================
--- testsuite/g++.dg/diagnostic/disable.C	(revision 0)
+++ testsuite/g++.dg/diagnostic/disable.C	(working copy)
@@ -0,0 +1,23 @@
+// { dg-options "-fno-templates -fno-multiple-inheritance -fno-virtual-inheritance -fno-namespaces" }
+
+#include <iostream>
+#include <algorithm>
+
+namespace foo { } // { dg-error "namepace" }
+
+template <typename X> X Foo (); // { dg-error "template" }
+
+struct B1 {};
+struct B2 {};
+struct V {};
+
+struct D :  B1, B2 {}; //  { dg-error "multiple" }
+
+struct E : virtual V {};  // { dg-error "virtual" }
+
+void Baz (int a, int b)
+{
+  std::swap (a, b);
+}
+
+