Merge pull request #5732 from tautschnig/void-extern

C/C++ front-end: void-typed symbols are permitted when extern

Author: tautschnig

regression/ansi-c/invalid_use_of_void1/main.c

@@ -1,3 +1,5 @@
+extern void this_is_ok;
+
 struct a
 {
 #ifdef void_member

src/ansi-c/c_typecheck_base.cpp

@@ -103,7 +103,7 @@ void c_typecheck_baset::typecheck_symbol(symbolt &symbol)
     symbol.pretty_name=new_name;
   }
 
-  if(!symbol.is_type && symbol.type.id() == ID_empty)
+  if(!symbol.is_type && !symbol.is_extern && symbol.type.id() == ID_empty)
   {
     error().source_location = symbol.location;
     error() << "void-typed symbol not permitted" << eom;

src/cpp/cpp_typecheck_code.cpp

@@ -448,7 +448,7 @@ void cpp_typecheckt::typecheck_decl(codet &code)
     if(is_typedef)
       continue;
 
-    if(!symbol.is_type && symbol.type.id() == ID_empty)
+    if(!symbol.is_type && !symbol.is_extern && symbol.type.id() == ID_empty)
     {
       error().source_location = symbol.location;
       error() << "void-typed symbol not permitted" << eom;

src/cpp/cpp_typecheck_declaration.cpp

@@ -148,7 +148,7 @@ void cpp_typecheckt::convert_non_template_declaration(
       declaration_type, declaration.storage_spec(),
       declaration.member_spec(), declarator);
 
-    if(!symbol.is_type && symbol.type.id() == ID_empty)
+    if(!symbol.is_type && !symbol.is_extern && symbol.type.id() == ID_empty)
     {
       error().source_location = symbol.location;
       error() << "void-typed symbol not permitted" << eom;