+2024-07-23 Bruno Haible <bruno@clisp.org>
+
+ strtof: Revisit underflow behaviour.
+ * doc/posix-functions/strtof.texi: Mention the macOS bug. Mention the
+ mingw overflow bug. Mention the underflow bugs on Cygwin 2.9 and mingw.
+ Mention that gradual underflow does not count as an error on Cygwin 2.9,
+ mingw, MSVC.
+ * m4/strtof.m4 (gl_FUNC_STRTOF): Test against the mingw overflow bug.
+ * tests/test-strtof.h (test_function): Add a gradual underflow test.
+ Check the sign in case of flush-to-zero underflow.
+
2024-07-23 Bruno Haible <bruno@clisp.org>
strtof, strtod, strtold: Fix underflow behaviour of system function.
@item
This function fails to parse @samp{NaN()} on some platforms:
-glibc-2.5, FreeBSD 6.2.
+glibc 2.5, FreeBSD 6.2.
+
+@item
+This function misparses @samp{nan(} on some platforms:
+macOS 10.6.6.
+
+@item
+This function fails to set @code{errno} upon overflow on some platforms:
+mingw 5.0.
+
+@item
+@c The term "underflow", as defined by ISO C23 ยง 7.12.1.(6), includes both
+@c "gradual underflow" (result is a denormalized number) and "flush-to-zero
+@c underflow" (result is zero).
+This function fails to set @code{errno} upon underflow on some platforms:
+Cygwin 2.9, mingw 5.0.
@end itemize
Portability problems not fixed by Gnulib:
platforms:
Mac OS X 10.5, FreeBSD 6.2, NetBSD 5.0, Cygwin, mingw, MSVC 14.
+@item
+This function fails to set @code{errno} upon gradual underflow (resulting
+in a denormalized number) on some platforms:
+MSVC 14.
+
@item
The replacement function does not always return correctly rounded results.
@end itemize
# strtof.m4
-# serial 3
+# serial 4
dnl Copyright (C) 2002-2003, 2006-2024 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
if (value != HUGE_VAL || term != (string + 3) || errno)
result |= 8;
}
+ {
+ /* In mingw 5.0 without __USE_MINGW_ANSI_STDIO and __USE_MINGW_STRTOX,
+ strtof does not set errno upon overflow. */
+ const char *string = "1e50";
+ char *term;
+ float value;
+ errno = 0;
+ value = strtof (string, &term);
+ if (value != HUGE_VAL || term != (string + 4) || errno != ERANGE)
+ result |= 8;
+ }
{
/* glibc 2.7 and cygwin 1.5.24 misparse "nan()". */
const char *string = "nan()";
result |= 16;
}
{
- /* darwin 10.6.1 misparses "nan(". */
+ /* Darwin 10.6.1 (macOS 10.6.6) misparses "nan(". */
const char *string = "nan(";
char *term;
float value = strtof (string, &term);
ASSERT (errno == 0);
}
- /* Overflow/underflow. */
+ /* Overflow. */
{
const char input[] = "1E1000000";
char *ptr;
ASSERT (ptr == input + 10);
ASSERT (errno == ERANGE);
}
+
+ /* Gradual underflow, resulting in a denormalized number. */
+ {
+ const char input[] = "1e-40";
+ char *ptr;
+ float result;
+ errno = 0;
+ result = my_strtof (input, &ptr);
+ ASSERT (0.0f < result && result <= FLT_MIN);
+ ASSERT (ptr == input + 5);
+#if !defined _MSC_VER
+ ASSERT (errno == ERANGE);
+#endif
+ }
+ {
+ const char input[] = "-1e-40";
+ char *ptr;
+ float result;
+ errno = 0;
+ result = my_strtof (input, &ptr);
+ ASSERT (-FLT_MIN <= result && result < 0.0f);
+ ASSERT (ptr == input + 6);
+#if !defined _MSC_VER
+ ASSERT (errno == ERANGE);
+#endif
+ }
+
+ /* Flush-to-zero underflow. */
{
const char input[] = "1E-100000";
char *ptr;
errno = 0;
result = my_strtof (input, &ptr);
ASSERT (-FLT_MIN <= result && result <= 0.0f);
-#if 0
- /* FIXME - this is glibc bug 5995; POSIX allows returning positive
- 0 on negative underflow, even though quality of implementation
- demands preserving the sign. Disable this test until fixed
- glibc is more prevalent. */
+ /* Negative underflow. Expect a negative sign, although POSIX allows +0.0f.
+ See also <https://sourceware.org/bugzilla/show_bug.cgi?id=5995>. */
ASSERT (!!signbit (result) == !!signbit (minus_zerof)); /* glibc-2.3.6, mingw */
-#endif
ASSERT (ptr == input + 10);
ASSERT (errno == ERANGE);
}
+
+ /* Space before the exponent. */
{
const char input[] = "1E 1000000";
char *ptr;