| Message ID | 56B911A2.9000100@redhat.com |
|---|---|
| State | New |
| Headers | show |
Jason Merrill <jason@redhat.com> writes: > The issue in this bug was that due to changes in the libstdc++ headers, the > built-in abs declaration was getting hidden by a using-declaration, so that > then when the built-in got an explicit declaration, the original > declaration wasn't there anymore and so the new declaration didn't get > marked as built-in. > > Fixed by overloading an anticipated built-in rather than clobbering it when > we see a using-declaration of the same name. > > Tested x86_64-pc-linux-gnu, applying to trunk. This patch broke Solaris bootstrap (seen on i386-pc-solaris2.12): /var/gcc/reghunt/trunk/gcc/c-family/c-lex.c: In function 'c_fileinfo* get_fileinfo(const char*)': /var/gcc/reghunt/trunk/gcc/c-family/c-lex.c:102:62: error: overloaded function with no contextual type information file_info_tree = splay_tree_new ((splay_tree_compare_fn) strcmp, ^~~~~~ /var/gcc/reghunt/trunk/gcc/c-family/c-lex.c:104:39: error: overloaded function with no contextual type information (splay_tree_delete_value_fn) free); ^~~~ make[3]: *** [c-family/c-lex.o] Error 1 Comparing c-lex.ii before and after the patch, I see that they differ like this: -# 508 "/var/gcc/reghunt/trunk/gcc/system.h" +# 452 "/var/gcc/reghunt/trunk/gcc/system.h" +extern void free (void *); +# 496 "/var/gcc/reghunt/trunk/gcc/system.h" +extern void *malloc (size_t); + + + +extern void *calloc (size_t, size_t); + + + +extern void *realloc (void *, size_t); + + + } and indeed auto-host.h changed: --- /var/gcc/reghunt/of-no-cti/28675/gcc/auto-host.h 2016-02-09 19:53:23.6030 78417 +0100 +++ auto-host.h 2016-02-09 20:28:39.946901958 +0100 @@ -743 +743 @@ -#define HAVE_DECL_CALLOC 1 +#define HAVE_DECL_CALLOC 0 @@ -846 +846 @@ -#define HAVE_DECL_FREE 1 +#define HAVE_DECL_FREE 0 @@ -937 +937 @@ -#define HAVE_DECL_MALLOC 1 +#define HAVE_DECL_MALLOC 0 @@ -958 +958 @@ -#define HAVE_DECL_REALLOC 1 +#define HAVE_DECL_REALLOC 0 The calloc configure test now fails like this: conftest.cpp: In function 'int main()': conftest.cpp:150:28: error: overloaded function with no contextual type information char *(*pfn) = (char *(*)) calloc ; ^~~~~~ The test boils down to typedef unsigned int size_t; namespace std { extern void *calloc(size_t, size_t); } using std::calloc; int main () { char *(*pfn) = (char *(*)) calloc ; return 0; } Rainer
commit 8f47c80051a73a75fb44900d9edb1444142c3d5f
Author: Jason Merrill <jason@redhat.com>
Date: Mon Feb 8 16:39:42 2016 -0500
PR c++/69657
* name-lookup.c (do_nonmember_using_decl): Leave anticipated
built-ins alone.
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 92d99aa..227d6f2 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -2583,15 +2583,6 @@ do_nonmember_using_decl (tree scope, tree name, tree oldval, tree oldtype,
decls.value = NULL_TREE;
}
- /* It is impossible to overload a built-in function; any explicit
- declaration eliminates the built-in declaration. So, if OLDVAL
- is a built-in, then we can just pretend it isn't there. */
- if (oldval
- && TREE_CODE (oldval) == FUNCTION_DECL
- && DECL_ANTICIPATED (oldval)
- && !DECL_HIDDEN_FRIEND_P (oldval))
- oldval = NULL_TREE;
-
if (decls.value)
{
/* Check for using functions. */
@@ -2610,6 +2601,10 @@ do_nonmember_using_decl (tree scope, tree name, tree oldval, tree oldtype,
{
tree new_fn = OVL_CURRENT (tmp);
+ /* Don't import functions that haven't been declared. */
+ if (DECL_ANTICIPATED (new_fn))
+ continue;
+
/* [namespace.udecl]
If a function declaration in namespace scope or block
@@ -2627,13 +2622,13 @@ do_nonmember_using_decl (tree scope, tree name, tree oldval, tree oldtype,
continue; /* this is a using decl */
else if (compparms_for_decl_and_using_decl (new_fn, old_fn))
{
- gcc_assert (!DECL_ANTICIPATED (old_fn)
- || DECL_HIDDEN_FRIEND_P (old_fn));
-
/* There was already a non-using declaration in
this scope with the same parameter types. If both
are the same extern "C" functions, that's ok. */
- if (decls_match (new_fn, old_fn))
+ if (DECL_ANTICIPATED (old_fn)
+ && !DECL_HIDDEN_FRIEND_P (old_fn))
+ /* Ignore anticipated built-ins. */;
+ else if (decls_match (new_fn, old_fn))
break;
else
{
@@ -2669,6 +2664,14 @@ do_nonmember_using_decl (tree scope, tree name, tree oldval, tree oldtype,
}
else
{
+ /* If we're declaring a non-function and OLDVAL is an anticipated
+ built-in, just pretend it isn't there. */
+ if (oldval
+ && TREE_CODE (oldval) == FUNCTION_DECL
+ && DECL_ANTICIPATED (oldval)
+ && !DECL_HIDDEN_FRIEND_P (oldval))
+ oldval = NULL_TREE;
+
*newval = decls.value;
if (oldval && !decls_match (*newval, oldval))
error ("%qD is already declared in this scope", name);
diff --git a/gcc/testsuite/g++.dg/lookup/builtin6.C b/gcc/testsuite/g++.dg/lookup/builtin6.C
new file mode 100644
index 0000000..456ade7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/builtin6.C
@@ -0,0 +1,23 @@
+// PR c++/69657
+// { dg-options -fdump-tree-gimple }
+// { dg-final { scan-tree-dump "ABS_EXPR" "gimple" } }
+
+namespace foo
+{
+ inline double
+ abs(double x)
+ { return __builtin_fabs(x); }
+}
+using foo::abs;
+
+extern "C" int abs(int);
+
+namespace bar {
+ using ::abs;
+}
+
+int
+wrapper (int x)
+{
+ return bar::abs (x) + bar::abs(x);
+}