From 7779876a6b06755e3bb2c94ee3ded50635bcb0fa Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 1 Feb 2018 14:06:55 -0500
Subject: c++: add extern declaration to the generated file

The extern declaration affects how the C++ compiler does name mangling of global
variables.  With:

    $ g++ -c -Wall -std=c++11 -o osx2win32.o osx2win32.cc
    $ nm osx2win32.o | grep code_map_osx_to_win32
    0000000000000000 B code_map_osx_to_win32
    00000000000000a1 t _GLOBAL__sub_I_code_map_osx_to_win32

Without:

    $ g++ -c -Wall -std=c++11 -o osx2win32.o osx2win32.cc
    $ nm osx2win32.o | grep code_map_osx_to_win32
    0000000000000000 b _ZL21code_map_osx_to_win32

Not that unlike C, without "extern" you get a local variable ("b"), while
"extern" is needed to get a global!

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 tools/keymap-gen | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/keymap-gen b/tools/keymap-gen
index 4d583a3..5d4dca3 100755
--- a/tools/keymap-gen
+++ b/tools/keymap-gen
@@ -641,10 +641,12 @@ class CppLanguageGenerator(CLanguageGenerator):
         totypename = "const " + self.strtypename if totype == self.TYPE_STRING else self.inttypename
         if fromtype == self.TYPE_INT:
             print("#include <vector>")
+            print("extern const std::vector<%s> %s;" % (totypename, varname));
             print("const std::vector<%s> %s = {" % (totypename, varname))
         else:
             print("#include <map>")
             print("#include <string>")
+            print("extern const std::map<const std::string, %s> %s;" % (totypename, varname))
             print("const std::map<const std::string, %s> %s = {" % (totypename, varname))
 
     def _array_end(self, fromtype, totype):
-- 
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