PR c++/18838

	2005-01-30  Mark Mitchell  <mark@codesourcery.com>
	PR c++/19367
	* name-lookup.c (do_nonmember_using_decl): Avoid overloading
	builtin declarations.

	PR c++/18838
	* g++.dg/lookup/builtin2.C: New test.
	2005-01-30  Mark Mitchell  <mark@codesourcery.com>
	PR c++/19367
	* g++.dg/lookup/builtin1.C: New test.


git-svn-id: https://gcc.gnu.org/svn/gcc/branches/gcc-3_4-rhl-branch@95657 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 57 insertions, 15 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 547b561457d..9411ae3a962 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2005-02-09  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR c++/18838
+	2005-01-30  Mark Mitchell  <mark@codesourcery.com>
+	PR c++/19367
+	* name-lookup.c (do_nonmember_using_decl): Avoid overloading
+	builtin declarations.
+
 2005-02-21  Alexandre Oliva  <aoliva@redhat.com>
 
 	PR c++/20028
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 80f4c2946c2..50313f857ed 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -2177,6 +2177,15 @@ do_nonmember_using_decl (tree scope, tree name, tree oldval, tree oldtype,
 	  oldval = 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))
+	oldval = NULL_TREE;
+
       *newval = oldval;
       for (tmp = decls.value; tmp; tmp = OVL_NEXT (tmp))
 	{
@@ -2200,27 +2209,19 @@ do_nonmember_using_decl (tree scope, tree name, tree oldval, tree oldtype,
 	      else if (compparms (TYPE_ARG_TYPES (TREE_TYPE (new_fn)),
 		  		  TYPE_ARG_TYPES (TREE_TYPE (old_fn))))
 		{
+		  if (DECL_ANTICIPATED (old_fn))
+		    abort ();
+
 	          /* 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 the OLD_FN was a builtin, there is now a
-			 real declaration.  */
-		      if (DECL_ANTICIPATED (old_fn))
-			DECL_ANTICIPATED (old_fn) = 0;
+		    break;
+		  else
+ 		    {
+		      error ("%D is already declared in this scope", name);
 		      break;
 		    }
-		  else if (!DECL_ANTICIPATED (old_fn))
-		    {
-		      /* If the OLD_FN was really declared, the
-			 declarations don't match.  */
-		      error ("`%D' is already declared in this scope", name);
-		      break;
-		    }
-
-		  /* If the OLD_FN was not really there, just ignore
-		     it and keep going.  */
 		}
 	    }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 45b3ea5e359..353c94f2835 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2005-02-09  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR c++/18838
+	* g++.dg/lookup/builtin2.C: New test.
+	2005-01-30  Mark Mitchell  <mark@codesourcery.com>
+	PR c++/19367
+	* g++.dg/lookup/builtin1.C: New test.
+
 2005-02-21  Alexandre Oliva  <aoliva@redhat.com>
 
 	PR c++/20028
diff --git a/gcc/testsuite/g++.dg/lookup/builtin2.C b/gcc/testsuite/g++.dg/lookup/builtin2.C
new file mode 100644
index 00000000000..ca9517ddc3e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/builtin2.C
@@ -0,0 +1,25 @@
+// PR c++/18838
+// { dg-do compile }
+
+extern "C" {
+  extern double fabs (double __x) throw () __attribute__ ((__const__));
+
+  __inline double
+  fabs (double __x) throw () { return __builtin_fabs (__x); }
+}
+
+double fail_me(double __x) { return fabs(__x); }
+
+namespace std
+{
+  using ::fabs;
+}
+
+typedef double (*realfn) (double);
+
+using std::fabs;
+
+int main ()
+{
+  realfn myfn = fabs;
+}