diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2d6f83b4bb7..876aad467c9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2004-10-08  Joseph S. Myers  <jsm@polyomino.org.uk>
+
+	* c-lex.c (interpret_float): Give a pedwarn rather than a warning
+	for an out-of-range floating point constant.
+	* builtins.c (fold_builtin_inf): Give a pedwarn rather than a
+	warning if the target format does not support infinities.
+
 2004-10-08  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* emit-rtl.c (last_label_num, base_label_num): Remove.
diff --git a/gcc/builtins.c b/gcc/builtins.c
index 76be4a7f619..255a47ba19c 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -5825,8 +5825,15 @@ fold_builtin_inf (tree type, int warn)
 {
   REAL_VALUE_TYPE real;
 
+  /* __builtin_inff is intended to be usable to define INFINITY on all
+     targets.  If an infinity is not available, INFINITY expands "to a
+     positive constant of type float that overflows at translation
+     time", footnote "In this case, using INFINITY will violate the
+     constraint in 6.4.4 and thus require a diagnostic." (C99 7.12#4).
+     Thus we pedwarn to ensure this constraint violation is
+     diagnosed.  */
   if (!MODE_HAS_INFINITIES (TYPE_MODE (type)) && warn)
-    warning ("target format does not support infinity");
+    pedwarn ("target format does not support infinity");
 
   real_inf (&real);
   return build_real (type, real);
diff --git a/gcc/c-lex.c b/gcc/c-lex.c
index 98f60f639d4..77c2e4c8ace 100644
--- a/gcc/c-lex.c
+++ b/gcc/c-lex.c
@@ -653,13 +653,13 @@ interpret_float (const cpp_token *token, unsigned int flags)
   real_from_string (&real, copy);
   real_convert (&real, TYPE_MODE (type), &real);
 
-  /* A diagnostic is required for "soft" overflow by some ISO C
-     testsuites.  This is not pedwarn, because some people don't want
-     an error for this.
-     ??? That's a dubious reason... is this a mandatory diagnostic or
-     isn't it?   -- zw, 2001-08-21.  */
+  /* 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)
-    warning ("floating constant exceeds range of %<%s%>", type_name);
+    pedwarn ("floating constant exceeds range of %<%s%>", type_name);
 
   /* Create a node with determined type and value.  */
   value = build_real (type, real);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 82f1f09d14c..6e1ee3dcf7a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2004-10-08  Joseph S. Myers  <jsm@polyomino.org.uk>
+
+	* gcc.dg/float-range-1.c, gcc.dg/float-range-2.c: New tests.
+
 2004-10-08  Joseph S. Myers  <jsm@polyomino.org.uk>
 
 	* gcc.dg/assign-warn-3.c: New test.
diff --git a/gcc/testsuite/gcc.dg/float-range-1.c b/gcc/testsuite/gcc.dg/float-range-1.c
new file mode 100644
index 00000000000..e14e345aba3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/float-range-1.c
@@ -0,0 +1,13 @@
+/* Floating constants outside the range of their type should receive a
+   pedwarn, not a warning.  */
+/* Origin: Joseph Myers <jsm@polyomino.org.uk> */
+/* { dg-do compile } */
+/* { dg-options "-ansi -pedantic-errors" } */
+
+void
+f (void)
+{
+  float a = 1e+100000000f; /* { dg-error "error: floating constant exceeds range of 'float'" } */
+  double b = 1e+100000000; /* { dg-error "error: floating constant exceeds range of 'double'" } */
+  long double c = 1e+100000000l; /* { dg-error "error: floating constant exceeds range of 'long double'" } */
+}
diff --git a/gcc/testsuite/gcc.dg/float-range-2.c b/gcc/testsuite/gcc.dg/float-range-2.c
new file mode 100644
index 00000000000..45447bc7912
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/float-range-2.c
@@ -0,0 +1,14 @@
+/* Floating constants outside the range of their type should receive a
+   pedwarn, not a warning.  This includes INFINITY if the target does
+   not support infinities.  */
+/* Origin: Joseph Myers <jsm@polyomino.org.uk> */
+/* { dg-do compile { target vax-*-* pdp11-*-* } } */
+/* { dg-options "-ansi -pedantic-errors" } */
+
+void
+f (void)
+{
+  float a = __builtin_inff (); /* { dg-error "error: target format does not support infinity" } */
+  double b = __builtin_inf (); /* { dg-error "error: target format does not support infinity" } */
+  long double c = __builtin_infl (); /* { dg-error "error: target format does not support infinity" } */
+}