Added BOOST_UNREACHABLE_RETURN workaround macro.

[SVN r16574]

config.htm

@@ -802,6 +802,14 @@ f(&amp;bar); // should choose #2.</pre>
         <td>The compiler does not support template template
         parameters.</td>
     </tr>
+    <tr>
+        <td>BOOST_NO_UNREACHABLE_RETURN_DETECTION</td>
+        <td>Compiler</td>
+        <td>If a return is unreachable, then no return statement
+        should be required, however some compilers insist on it,
+        while other issue a bunch of warnings if it is in fact
+        present.</td>
+    </tr>
     <tr>
         <td valign="top" width="51%">BOOST_NO_USING_TEMPLATE</td>
         <td valign="top" width="16%">Compiler</td>
@@ -904,9 +912,9 @@ present.</p>
         <td>BOOST_HAS_NRVO</td>
         <td>Compiler</td>
         <td>Indicated that the compiler supports the named return
-        value optimization (NRVO). Used to select the most efficient
+        value optimization (NRVO). Used to select the most
-        implementation for some function. See
+        efficient implementation for some function. See <a
-        <a href="../../boost/operators.hpp">boost/operators.hpp</a> 
+        href="../../boost/operators.hpp">boost/operators.hpp</a>
         for example.</td>
     </tr>
     <tr>
@@ -1071,6 +1079,12 @@ provide workarounds for compiler/standard library defects.</p>
 };</pre>
         </td>
     </tr>
+    <tr>
+        <td>BOOST_UNREACHABLE_RETURN(result)</td>
+        <td>Normally evaluates to nothing, but evaluates to <font
+        face="Courier New">return x;</font> if the compiler
+        requires a return, even when it can never be reached.</td>
+    </tr>
     <tr>
         <td valign="top" width="50%">BOOST_USE_FACET(Type, loc)</td>
         <td valign="top" width="50%">When the standard library

include/boost/config/suffix.hpp

@@ -309,6 +309,17 @@ namespace std {
 #  define BOOST_NESTED_TEMPLATE
 #endif
 
+// BOOST_UNREACHABLE_RETURN(x) workaround -------------------------------------//
+// Normally evaluates to nothing, unless BOOST_NO_UNREACHABLE_RETURN_DETECTION
+// is defined, in which case it evaluates to return x; Use when you have a return
+// statement that can never be reached.
+
+#ifdef BOOST_NO_UNREACHABLE_RETURN_DETECTION
+#  define BOOST_UNREACHABLE_RETURN(x) return x;
+#else
+#  define BOOST_UNREACHABLE_RETURN(x)
+#endif
+
 // BOOST_DEDUCED_TYPENAME workaround ------------------------------------------//
 //
 // Some compilers don't support the use of `typename' for dependent

test/Jamfile

@@ -1,6 +1,6 @@
 #
 # Regression test Jamfile for boost configuration setup.
-# This file was automatically generated on Tue Nov 12 11:07:30  2002,
+# This file was automatically generated on Mon Dec  9 12:06:12  2002,
 # do not edit by hand...
 #
 subproject libs/config/test ;
@@ -102,6 +102,9 @@ test-suite "BOOST_NO_PRIVATE_IN_AGGREGATE" :
 test-suite "BOOST_NO_POINTER_TO_MEMBER_CONST" : 
 [ run no_ptr_mem_const_pass.cpp <lib>../../test/build/prg_exec_monitor ]
 [ link-fail no_ptr_mem_const_fail.cpp <lib>../../test/build/prg_exec_monitor ] ;
+test-suite "BOOST_NO_UNREACHABLE_RETURN_DETECTION" : 
+[ run no_ret_det_pass.cpp <lib>../../test/build/prg_exec_monitor ]
+[ link-fail no_ret_det_fail.cpp <lib>../../test/build/prg_exec_monitor ] ;
 test-suite "BOOST_NO_STRINGSTREAM" : 
 [ run no_sstream_pass.cpp <lib>../../test/build/prg_exec_monitor ]
 [ link-fail no_sstream_fail.cpp <lib>../../test/build/prg_exec_monitor ] ;

test/config_info.cpp

@@ -915,9 +915,11 @@ void print_boost_macros()
    PRINT_MACRO(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION);
    PRINT_MACRO(BOOST_NO_TEMPLATE_TEMPLATES);
    PRINT_MACRO(BOOST_NO_TEMPLATED_ITERATOR_CONSTRUCTORS);
+   PRINT_MACRO(BOOST_NO_UNREACHABLE_RETURN_DETECTION);
    PRINT_MACRO(BOOST_NO_USING_TEMPLATE);
    PRINT_MACRO(BOOST_NO_VOID_RETURNS);
    PRINT_MACRO(BOOST_STD_EXTENSION_NAMESPACE);
+   PRINT_MACRO(BOOST_UNREACHABLE_RETURN(0));
 }
 
 void print_separator()

test/config_test.cpp

@@ -10,7 +10,7 @@
 
 // Do not edit this file, it was generated automatically by
 // ../tools/generate from boost_*.cxx on
-// Tue Nov 12 11:07:30  2002
+// Mon Dec  9 12:06:12  2002
 
 #include <boost/config.hpp>
 #define BOOST_INCLUDE_MAIN
@@ -167,6 +167,11 @@ namespace boost_no_private_in_aggregate = empty_boost;
 #else
 namespace boost_no_pointer_to_member_const = empty_boost;
 #endif
+#ifndef BOOST_NO_UNREACHABLE_RETURN_DETECTION
+#include "boost_no_ret_det.cxx"
+#else
+namespace boost_no_unreachable_return_detection = empty_boost;
+#endif
 #ifndef BOOST_NO_STRINGSTREAM
 #include "boost_no_sstream.cxx"
 #else
@@ -413,6 +418,7 @@ int test_main( int, char *[] )
    BOOST_TEST(0 == boost_no_std_distance::test());
    BOOST_TEST(0 == boost_no_std_allocator::test());
    BOOST_TEST(0 == boost_no_stringstream::test());
+   BOOST_TEST(0 == boost_no_unreachable_return_detection::test());
    BOOST_TEST(0 == boost_no_pointer_to_member_const::test());
    BOOST_TEST(0 == boost_no_private_in_aggregate::test());
    BOOST_TEST(0 == boost_no_template_partial_specialization::test());

test/no_ret_det_fail.cpp

@@ -0,0 +1,35 @@
+
+//  (C) Copyright Boost.org 1999. Permission to copy, use, modify, sell and
+//  distribute this software is granted provided this copyright notice appears
+//  in all copies. This software is provided "as is" without express or implied
+//  warranty, and with no claim as to its suitability for any purpose.
+
+// Test file for macro BOOST_NO_UNREACHABLE_RETURN_DETECTION
+// This file should not compile, if it does then
+// BOOST_NO_UNREACHABLE_RETURN_DETECTION need not be defined.
+// see boost_no_ret_det.cxx for more details
+
+// Do not edit this file, it was generated automatically by
+// ../tools/generate from boost_no_ret_det.cxx on
+// Mon Dec  9 12:06:12  2002
+
+// Must not have BOOST_ASSERT_CONFIG set; it defeats
+// the objective of this file:
+#ifdef BOOST_ASSERT_CONFIG
+#  undef BOOST_ASSERT_CONFIG
+#endif
+
+#include <boost/config.hpp>
+#include "test.hpp"
+
+#ifdef BOOST_NO_UNREACHABLE_RETURN_DETECTION
+#include "boost_no_ret_det.cxx"
+#else
+#error "this file should not compile"
+#endif
+
+int cpp_main( int, char *[] )
+{
+   return boost_no_unreachable_return_detection::test();
+}  
+   

test/no_ret_det_pass.cpp

@@ -0,0 +1,35 @@
+
+//  (C) Copyright Boost.org 1999. Permission to copy, use, modify, sell and
+//  distribute this software is granted provided this copyright notice appears
+//  in all copies. This software is provided "as is" without express or implied
+//  warranty, and with no claim as to its suitability for any purpose.
+
+// Test file for macro BOOST_NO_UNREACHABLE_RETURN_DETECTION
+// This file should compile, if it does not then
+// BOOST_NO_UNREACHABLE_RETURN_DETECTION needs to be defined.
+// see boost_no_ret_det.cxx for more details
+
+// Do not edit this file, it was generated automatically by
+// ../tools/generate from boost_no_ret_det.cxx on
+// Mon Dec  9 12:06:12  2002
+
+// Must not have BOOST_ASSERT_CONFIG set; it defeats
+// the objective of this file:
+#ifdef BOOST_ASSERT_CONFIG
+#  undef BOOST_ASSERT_CONFIG
+#endif
+
+#include <boost/config.hpp>
+#include "test.hpp"
+
+#ifndef BOOST_NO_UNREACHABLE_RETURN_DETECTION
+#include "boost_no_ret_det.cxx"
+#else
+namespace boost_no_unreachable_return_detection = empty_boost;
+#endif
+
+int cpp_main( int, char *[] )
+{
+   return boost_no_unreachable_return_detection::test();
+}  
+