+2000-02-18 Geoff Keating <geoffk@cygnus.com>
+
+ * invoke.texi (Warning Options): Add an explanation of why
+ you might want the -Wfloat-equal flag.
+
Fri Feb 18 20:08:57 2000 Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
* bitmap.c (bitmap_operation): Avoid using -1 for index since unsigned.
@item -Wfloat-equal
Warn if floating point values are used in equality comparisons.
+The idea behind this is that sometimes it is convenient (for the
+programmer) to consider floating-point values as approximations to
+infinitely precise real numbers. If you are doing this, then you need
+to compute (by analysing the code, or in some other way) the maximum or
+likely maximum error that the computation introduces, and allow for it
+when performing comparisons (and when producing output, but that's a
+different problem). In particular, instead of testing for equality, you
+would check to see whether the two values have ranges that overlap; and
+this is done with the relational operators, so equality comparisons are
+probably mistaken.
+
@item -Wtraditional (C only)
Warn about certain constructs that behave differently in traditional and
ANSI C.