2007-03-22 Manuel Lopez-Ibanez <manu@gcc.gnu.org>

	PR other/23572
	* c-lex.c (interpret_float): On overflow, emit pedantic warning if
	infinities not supported, otherwise emit warning if -Woverflow. On
	underflow, emit warning if -Woverflow.
	* real.c (real_from_string): Return -1 if underflow, +1 if overflow
	and 0 otherwise.
	* real.h (real_from_string): Update declaration
testsuite/
	* gcc.dg/float-range-4.c: New.
	* gcc.dg/float-range-1.c: Update. Test for a warning.
	* gcc.dg/float-range-3.c: New.
	* gcc.dg/float-range-5.c: New.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@123137 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 17 insertions, 5 deletions

diff --git a/gcc/c-lex.c b/gcc/c-lex.c
index 108bc5cff17..a89643c6046 100644
--- a/gcc/c-lex.c
+++ b/gcc/c-lex.c
@@ -681,11 +681,23 @@ interpret_float (const cpp_token *token, unsigned int flags)
 
   /* Both C and C++ require a diagnostic for a floating constant
      outside the range of representable values of its type.  Since we
-     have __builtin_inf* to produce an infinity, it might now be
-     appropriate for this to be a mandatory pedwarn rather than
-     conditioned on -pedantic.  */
-  if (REAL_VALUE_ISINF (real) && pedantic)
-    pedwarn ("floating constant exceeds range of %qT", type);
+     have __builtin_inf* to produce an infinity, this is now a
+     mandatory pedwarn if the target does not support infinities.  */
+  if (REAL_VALUE_ISINF (real)) 
+    {
+      if (!MODE_HAS_INFINITIES (TYPE_MODE (type)))
+	pedwarn ("floating constant exceeds range of %qT", type);
+      else
+	warning (OPT_Woverflow, "floating constant exceeds range of %qT", type);
+    }
+  /* We also give a warning if the value underflows.  */
+  else if (REAL_VALUES_EQUAL (real, dconst0))
+    {
+      REAL_VALUE_TYPE realvoidmode;
+      int overflow = real_from_string (&realvoidmode, copy);
+      if (overflow < 0 || !REAL_VALUES_EQUAL (realvoidmode, dconst0)) 
+	warning (OPT_Woverflow, "floating constant truncated to zero");
+    }
 
   /* Create a node with determined type and value.  */
   value = build_real (type, real);