RFC: fix PR c++/15116

[Tom Tromey <tromey@redhat.com>]

This fixes PR c++/15116.

The bug is that overloading doesn't work if one of the arguments has
function type.

I fixed this by updating types_equal to account for this situation.
This allows rank_one_type to work properly.


A couple notes on this.

First, types_equal is fairly primitive.
There is a fuller deep-comparison approach in py-type.c.
However, that may be overkill here -- and actually seems like it could
break overload resolution (see the gross integer_types_same_name_p).

Second, overload resolution can actually do a kind of second overload
resolution, according to the standard.  This is well-formed:

    int f(int x) { return x; }
    double f(double x) { return x; }

    int overload(int x, int (*f)(int)) { return f(x); }

    int main()
    {
      return overload(0, f);
    }

... and here we would have to do overload resolution on the argument
'f'.

I will file a separate bug for this.


Built and regtested on x86-64 Fedora 16.
New test case included.

Tom

    	PR c++/15116:
    	* gdbtypes.c (types_equal): Handle TYPE_CODE_FUNC.
    
    	* gdb.cp/overload.cc (intintfunc): New.
    	* gdb.cp/overload.exp: Add regression test.

diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index 12730d7..a1c4018 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -2456,6 +2456,25 @@ types_equal (struct type *a, struct type *b)
   if (a == b)
     return 1;
 
+  /* Two function types are equal if their argument and return types
+     are equal.  */
+  if (TYPE_CODE (a) == TYPE_CODE_FUNC)
+    {
+      int i;
+
+      if (TYPE_NFIELDS (a) != TYPE_NFIELDS (b))
+	return 0;
+      
+      if (!types_equal (TYPE_TARGET_TYPE (a), TYPE_TARGET_TYPE (b)))
+	return 0;
+
+      for (i = 0; i < TYPE_NFIELDS (a); ++i)
+	if (!types_equal (TYPE_FIELD_TYPE (a, i), TYPE_FIELD_TYPE (b, i)))
+	  return 0;
+
+      return 1;
+    }
+
   return 0;
 }
 
diff --git a/gdb/testsuite/gdb.cp/overload.cc b/gdb/testsuite/gdb.cp/overload.cc
index ba0678f..5c782a4 100644
--- a/gdb/testsuite/gdb.cp/overload.cc
+++ b/gdb/testsuite/gdb.cp/overload.cc
@@ -97,6 +97,8 @@ class D: C {};
 int bar (A) { return 11; }
 int bar (B) { return 22; }
 
+int intintfunc (int x) { return x; }
+
 int main () 
 {
     char arg2 = 2;
diff --git a/gdb/testsuite/gdb.cp/overload.exp b/gdb/testsuite/gdb.cp/overload.exp
index 3ebc642..9d49516 100644
--- a/gdb/testsuite/gdb.cp/overload.exp
+++ b/gdb/testsuite/gdb.cp/overload.exp
@@ -139,6 +139,9 @@ gdb_test "print foo_instance3" "\\$\[0-9\]+ = \{ifoo = 222, ccpfoo = $hex \"A\"\
 gdb_test "print foo_instance1.overloadargs(1)" "\\$\[0-9\]+ = 1" \
     "print call overloaded func 1 arg"
 
+# Regression test for overloading with function pointer type.
+gdb_test "print foo_instance1.overloadfnarg(23, intintfunc)" " = 23"
+
 # If GDB fails to restore the selected frame properly after the
 # inferior function call above (see GDB PR 1155 for an explanation of
 # why this might happen), all the subsequent tests will fail.  We