Fix overload resolution involving rvalue references and cv qualifiers.

The following patch fixes several outstanding overload resolution problems
with rvalue references and cv qualifiers in the test suite. The tests for
these problems typically passed with one compiler version and failed with
another. This behavior occurs because of the ordering of the overloaded
functions in the debug info. So the first best match "won out" over the
a subsequent better match.

One of the bugs addressed by this patch is the failure of rank_one_type to
account for type equality of two overloads based on CV qualifiers.  This was
leading directly to problems evaluating rvalue reference overload quality,
but it is also highlighted in gdb.cp/oranking.exp, where two test KFAIL as
a result of this shortcoming.

I found the overload resolution code committed with the rvalue reference
patch (f9aeb8d49) needlessly over-complicated, and I have greatly simplified
it. This fixes some KFAILing tests in gdb.exp/rvalue-ref-overload.exp.

gdb/ChangeLog

	* gdbtypes.c (LVALUE_REFERENCE_TO_RVALUE_BINDING_BADNESS)
	DIFFERENT_REFERENCE_TYPE_BADNESS): Remove.
	(CV_CONVERSION_BADNESS): Define.
	(rank_one_type): Remove overly restrictive rvalue reference
	rank checks.
	Add cv-qualifier checks and subranks for type equality.
	* gdbtypes.h (REFERENCE_CONVERSION_RVALUE,
	REFERENCE_CONVERSION_CONST_LVALUE, CV_CONVERSION_BADNESS,
	CV_CONVERSION_CONST, CV_CONVERSION_VOLATILE): Declare.

gdb/testsuite/ChangeLog

	* gdb.cp/oranking.cc (test15): New function.
	(main): Call test15 and declare additional variables for testing.
	* gdb.cp/oranking.exp: Remove kfail status for "p foo4(&a)" and
	"p foo101('abc')" tests.
	* gdb.cp/rvalue-ref-overloads.exp: Remove kfail status for
	"lvalue reference overload" test.
	* gdb.cp/rvalue-ref-params.exp: Remove kfail status for
	"print value of f1 on Child&& in f2" test.

5 files changed, 39 insertions, 6 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index c4d5b79..a835a40 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,15 @@
+2017-04-27  Keith Seitz  <keiths@redhat.com>
+
+	* gdb.cp/oranking.cc (test15): New function.
+	(main): Call test15 and declare additional variables for testing.
+	* gdb.cp/oranking.exp: Remove kfail status for "p foo4(&a)" and
+	"p foo101('abc')" tests.
+	Add tests for cv qualifier overloads.
+	* gdb.cp/rvalue-ref-overloads.exp: Remove kfail status for
+	"lvalue reference overload" test.
+	* gdb.cp/rvalue-ref-params.exp: Remove kfail status for
+	"print value of f1 on Child&& in f2" test.
+
 2017-04-19  Pedro Alves  <palves@redhat.com>
 
 	* gdb.threads/threadapply.exp (kill_and_remove_inferior): New
diff --git a/gdb/testsuite/gdb.cp/oranking.cc b/gdb/testsuite/gdb.cp/oranking.cc
index dc1972a..bd2f51b 100644
--- a/gdb/testsuite/gdb.cp/oranking.cc
+++ b/gdb/testsuite/gdb.cp/oranking.cc
@@ -147,6 +147,23 @@ int test14 (){
   return foo14(e); // 46
 }
 
+/* Test cv qualifier overloads.  */
+int foo15 (char *arg) { return 47; }
+int foo15 (const char *arg) { return 48; }
+int foo15 (volatile char *arg) { return 49; }
+int foo15 (const volatile char *arg) { return 50; }
+static int
+test15 ()
+{
+  char *c = 0;
+  const char *cc = 0;
+  volatile char *vc = 0;
+  const volatile char *cvc = 0;
+
+  // 47 + 48 + 49 + 50 = 194
+  return foo15 (c) + foo15 (cc) + foo15 (vc)  + foo15 (cvc);
+}
+
 int main() {
   B b;
   foo0(b);
@@ -203,5 +220,10 @@ int main() {
   foo14(e);
   test14();
 
+  const char *cc = 0;
+  volatile char *vc = 0;
+  const volatile char *cvc = 0;
+  test15 ();
+
   return 0; // end of main
 }
diff --git a/gdb/testsuite/gdb.cp/oranking.exp b/gdb/testsuite/gdb.cp/oranking.exp
index 69efb0c..dc7c78b 100644
--- a/gdb/testsuite/gdb.cp/oranking.exp
+++ b/gdb/testsuite/gdb.cp/oranking.exp
@@ -48,7 +48,6 @@ gdb_test "p test3()"    "21"
 gdb_test "p foo3(1.0f)" "21"
 
 gdb_test "p test4()"  "24"
-setup_kfail "gdb/12098" *-*-*
 gdb_test "p foo4(&a)" "24"
 
 gdb_test "p test5()" "26"
@@ -71,7 +70,6 @@ setup_kfail "gdb/12098" *-*-*
 gdb_test "p foo10(amp)" "216"
 
 gdb_test "p test101()"   "218"
-setup_kfail "gdb/12098" *-*-*
 gdb_test "p foo101(\"abc\")" "218"
 
 gdb_test "p test11()"   "32"
@@ -91,5 +89,8 @@ gdb_test "p test14()" "46"
 setup_kfail "gdb/12096" *-*-*
 gdb_test "p foo14(e)" "46"
 
-
-
+gdb_test "p test15 ()" "194"
+gdb_test "p foo15 (c)" "47"
+gdb_test "p foo15 (cc)" "48"
+gdb_test "p foo15 (vc)" "49"
+gdb_test "p foo15 (cvc)" "50"
diff --git a/gdb/testsuite/gdb.cp/rvalue-ref-overload.exp b/gdb/testsuite/gdb.cp/rvalue-ref-overload.exp
index e729209..5cfd34e 100644
--- a/gdb/testsuite/gdb.cp/rvalue-ref-overload.exp
+++ b/gdb/testsuite/gdb.cp/rvalue-ref-overload.exp
@@ -60,7 +60,6 @@ gdb_test "print foo_rr_instance1.overload1arg(static_cast<foo&&>(arg))" \
     "print call overloaded func foo && arg"
 
 # Test lvalue vs rvalue function overloads
-setup_kfail "c++/15372" "*-*-*"
 gdb_test "print f (i)" "= 1" "lvalue reference overload"
 
 gdb_test "print f (ci)" "= 2" "lvalue reference to const overload"
diff --git a/gdb/testsuite/gdb.cp/rvalue-ref-params.exp b/gdb/testsuite/gdb.cp/rvalue-ref-params.exp
index 303b447..611b592 100644
--- a/gdb/testsuite/gdb.cp/rvalue-ref-params.exp
+++ b/gdb/testsuite/gdb.cp/rvalue-ref-params.exp
@@ -48,7 +48,6 @@ set t "print value of Child&& in f2"
 gdb_start_again "marker2 here" $t
 gdb_test "print C" ".*id = 42.*" $t
 
-setup_kfail "c++/15372" "*-*-*"
 gdb_test "print f1 (static_cast<Child&&> (C))" ".* = 42.*" \
     "print value of f1 on Child&& in f2"