re PR c++/37276 (Trouble with some (C99?) math builtins and namespace std)

	PR c++/37276
	* decl.c (decls_match): A non-extern-C declaration doesn't match
	a builtin extern-C declaration.

From-SVN: r149638

7 files changed, 41 insertions, 4 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index d43341b8..3197057 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,9 @@
 2009-07-14  Jason Merrill  <jason@redhat.com>
 
+	PR c++/37276
+	* decl.c (decls_match): A non-extern-C declaration doesn't match
+	a builtin extern-C declaration.
+
 	PR c++/40746
 	* name-lookup.c (qualified_lookup_using_namespace): Don't stop
 	looking in used namespaces just because we found something on
@@ -8,8 +12,6 @@
 	PR c++/40740
 	* semantics.c (perform_koenig_lookup): Handle empty template args.
 
-2009-07-13  Jason Merrill  <jason@redhat.com>
-
 	* call.c (build_over_call): Use can_trust_pointer_alignment.
 
 2009-07-14  Dodji Seketeli  <dodji@redhat.com>
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index d7a0e0d..e1b6678 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -932,6 +932,14 @@ decls_match (tree newdecl, tree olddecl)
 		&& DECL_EXTERN_C_P (olddecl)))
 	return 0;
 
+#ifdef NO_IMPLICIT_EXTERN_C
+      /* A new declaration doesn't match a built-in one unless it
+	 is also extern "C".  */
+      if (DECL_BUILT_IN (olddecl)
+	  && DECL_EXTERN_C_P (olddecl) && !DECL_EXTERN_C_P (newdecl))
+	return 0;
+#endif
+
       if (TREE_CODE (f1) != TREE_CODE (f2))
 	return 0;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1fa70ed..75cd8c06 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,11 @@
 2009-07-14  Jason Merrill  <jason@redhat.com>
 
+	PR c++/37276
+	* g++.dg/lookup/builtin5.C: New.
+	* g++.dg/other/error22.C: Add missing extern "C".
+	* g++.dg/warn/Warray-bounds.C: Likewise.
+	* gcc.dg/compat/compat-common.h: Likewise.
+
 	PR c++/40746
 	* g++.dg/lookup/using20.C: New.
 
diff --git a/gcc/testsuite/g++.dg/lookup/builtin5.C b/gcc/testsuite/g++.dg/lookup/builtin5.C
new file mode 100644
index 0000000..1bd67dc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/builtin5.C
@@ -0,0 +1,16 @@
+// PR c++/37276
+
+// { dg-final { scan-assembler "_ZSt5atanhd" } }
+
+namespace std
+{
+  inline double
+  atanh(double __x)
+  { return __builtin_atanh(__x); }
+}
+
+int main()
+{
+  std::atanh(.3);
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/other/error22.C b/gcc/testsuite/g++.dg/other/error22.C
index 8b7a9e9..225dcae 100644
--- a/gcc/testsuite/g++.dg/other/error22.C
+++ b/gcc/testsuite/g++.dg/other/error22.C
@@ -1,7 +1,7 @@
 // PR c++/34394
 // { dg-do compile }
 
-extern double fabs (double);
+extern "C" double fabs (double);
 
 void foo (double x)
 {
diff --git a/gcc/testsuite/g++.dg/warn/Warray-bounds.C b/gcc/testsuite/g++.dg/warn/Warray-bounds.C
index d53af52..61c7c5d 100644
--- a/gcc/testsuite/g++.dg/warn/Warray-bounds.C
+++ b/gcc/testsuite/g++.dg/warn/Warray-bounds.C
@@ -3,8 +3,9 @@
 
 int a[10];
 
+extern "C" __SIZE_TYPE__ strlen(const char *s);
+
 static inline int n(void) {
-    __SIZE_TYPE__ strlen(const char *s);
     return strlen("12345");
 }
 
diff --git a/gcc/testsuite/gcc.dg/compat/compat-common.h b/gcc/testsuite/gcc.dg/compat/compat-common.h
index 40d4e08..8a92ea3 100644
--- a/gcc/testsuite/gcc.dg/compat/compat-common.h
+++ b/gcc/testsuite/gcc.dg/compat/compat-common.h
@@ -47,5 +47,9 @@
 #endif
 #endif
 
+#ifdef __cplusplus
+extern "C" void abort (void);
+#else
 extern void abort (void);
+#endif
 extern int fails;