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re PR c++/27227 (rejects valid code with some extern "C") 

PR c++/27227
	* decl.c (decls_match): Allow an extern "C" variable declarations
	from different namespaces to match.
	(duplicate_decls): Disallow redeclaring a variable with a
	different linkage specification.
	PR c++/27227
	* g++.dg/lookup/linkage1.C: New test.
	* g++.dg/lookup/linkage2.C: Likewise.

From-SVN: r114647
This commit is contained in:
Mark Mitchell 2006-06-14 17:44:36 +00:00 committed by Mark Mitchell
parent c3b11a40d0
commit ace4831de9
5 changed files with 65 additions and 6 deletions
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8
gcc/cp/ChangeLog
View File

@ -1,3 +1,11 @@
2006-06-13 Mark Mitchell <mark@codesourcery.com>
PR c++/27227
* decl.c (decls_match): Allow an extern "C" variable declarations
from different namespaces to match.
(duplicate_decls): Disallow redeclaring a variable with a
different linkage specification.
2006-06-13 Jakub Jelinek <jakub@redhat.com>
PR middle-end/27793

46
gcc/cp/decl.c
View File

@ -999,7 +999,13 @@ decls_match (tree newdecl, tree olddecl)
/* Need to check scope for variable declaration (VAR_DECL).
For typedef (TYPE_DECL), scope is ignored. */
if (TREE_CODE (newdecl) == VAR_DECL
&& CP_DECL_CONTEXT (newdecl) != CP_DECL_CONTEXT (olddecl))
&& CP_DECL_CONTEXT (newdecl) != CP_DECL_CONTEXT (olddecl)
/* [dcl.link]
Two declarations for an object with C language linkage
with the same name (ignoring the namespace that qualify
it) that appear in different namespace scopes refer to
the same object. */
&& !(DECL_EXTERN_C_P (olddecl) && DECL_EXTERN_C_P (newdecl)))
return 0;
if (TREE_TYPE (newdecl) == error_mark_node)
@ -1453,14 +1459,42 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
warning (0, "prototype for %q+#D", newdecl);
warning (0, "%Jfollows non-prototype definition here", olddecl);
}
else if (TREE_CODE (olddecl) == FUNCTION_DECL
else if ((TREE_CODE (olddecl) == FUNCTION_DECL
|| TREE_CODE (olddecl) == VAR_DECL)
&& DECL_LANGUAGE (newdecl) != DECL_LANGUAGE (olddecl))
{
/* extern "C" int foo ();
int foo () { bar (); }
is OK. */
/* [dcl.link]
If two declarations of the same function or object
specify different linkage-specifications ..., the program
is ill-formed.... Except for functions with C++ linkage,
a function declaration without a linkage specification
shall not precede the first linkage specification for
that function. A function can be declared without a
linkage specification after an explicit linkage
specification has been seen; the linkage explicitly
specified in the earlier declaration is not affected by
such a function declaration.
DR 563 raises the question why the restrictions on
functions should not also apply to objects. Older
versions of G++ silently ignore the linkage-specification
for this example:
namespace N {
extern int i;
extern "C" int i;
}
which is clearly wrong. Therefore, we now treat objects
like functions. */
if (current_lang_depth () == 0)
SET_DECL_LANGUAGE (newdecl, DECL_LANGUAGE (olddecl));
{
/* There is no explicit linkage-specification, so we use
the linkage from the previous declaration. */
if (!DECL_LANG_SPECIFIC (newdecl))
retrofit_lang_decl (newdecl);
SET_DECL_LANGUAGE (newdecl, DECL_LANGUAGE (olddecl));
}
else
{
error ("previous declaration of %q+#D with %qL linkage",

6
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,9 @@
2006-06-14 Mark Mitchell <mark@codesourcery.com>
PR c++/27227
* g++.dg/lookup/linkage1.C: New test.
* g++.dg/lookup/linkage2.C: Likewise.
2006-06-14 Andreas Krebbel <krebbel1@de.ibm.com>
PR middle-end/27959

4
gcc/testsuite/g++.dg/lookup/linkage1.C Normal file
View File

@ -0,0 +1,4 @@
// DR 563
extern int i; // { dg-error "linkage" }
extern "C" int i; // { dg-error "linkage" }

7
gcc/testsuite/g++.dg/lookup/linkage2.C Normal file
View File

@ -0,0 +1,7 @@
// PR c++/27227
namespace x {
extern "C" const int y;
}
using x::y;
extern "C" int const y=0;