[COMMITTED] Disable tree to bool conversion in frange::update_nan.

[Aldy Hernandez via Gcc-patches]

We have a set_nan(type) method which can be confused with
update_nan(bool) because of the silent conversion of pointers to bool.
Currently, if you call update_nan(tree), you'll set the possibility of
NAN with a sign of true if tree is non-null.  This is prone to error
and this patch disallows this behavior.

gcc/ChangeLog:

        * value-range.cc (frange::set_nonnegative): Pass bool to
        update_nan.
        * value-range.h: Disallow conversion to bool in update_nan().
---
 gcc/value-range.cc | 2 +-
 gcc/value-range.h  | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index e07d2aa9a5b..26a2b782e2c 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -779,7 +779,7 @@ frange::set_nonnegative (tree type)
 
   // Set +NAN as the only possibility.
   if (HONOR_NANS (type))
-    update_nan (/*sign=*/0);
+    update_nan (/*sign=*/false);
 }
 
 // Here we copy between any two irange's.  The ranges can be legacy or
diff --git a/gcc/value-range.h b/gcc/value-range.h
index 9d630e40f78..cb5e9d0522c 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -317,6 +317,7 @@ public:
   const REAL_VALUE_TYPE &upper_bound () const;
   void update_nan ();
   void update_nan (bool sign);
+  void update_nan (tree) = delete; // Disallow silent conversion to bool.
   void clear_nan ();
 
   // fpclassify like API
-- 
2.37.3