C2x scanf binary constant handling

C2x adds binary integer constants starting with 0b or 0B, and supports
those constants for the %i scanf format (in addition to the %b format,
which isn't yet implemented for scanf in glibc).  Implement that scanf
support for glibc.

As with the strtol support, this is incompatible with previous C
standard versions, in that such an input string starting with 0b or 0B
was previously required to be parsed as 0 (with the rest of the input
potentially matching subsequent parts of the scanf format string).
Thus this patch adds 12 new __isoc23_* functions per long double
format (12, 24 or 36 depending on how many long double formats the
glibc configuration supports), with appropriate header redirection
support (generally very closely following that for the __isoc99_*
scanf functions - note that __GLIBC_USE (DEPRECATED_SCANF) takes
precedence over __GLIBC_USE (C2X_STRTOL), so the case of GNU
extensions to C89 continues to get old-style GNU %a and does not get
this new feature).  The function names would remain as __isoc23_* even
if C2x ends up published in 2024 rather than 2023.

When scanf %b support is added, I think it will be appropriate for all
versions of scanf to follow C2x rules for inputs to the %b format
(given that there are no compatibility concerns for a new format).

Tested for x86_64 (full glibc testsuite).  The first version was also
tested for powerpc (32-bit) and powerpc64le (stdio-common/ and wcsmbs/
tests), and with build-many-glibcs.py.

1 files changed, 44 insertions, 0 deletions

diff --git a/sysdeps/ieee754/ldbl-opt/Makefile b/sysdeps/ieee754/ldbl-opt/Makefile
index 1d01846476..5b72474aa4 100644
--- a/sysdeps/ieee754/ldbl-opt/Makefile
+++ b/sysdeps/ieee754/ldbl-opt/Makefile
@@ -42,6 +42,10 @@ libnldbl-calls = asprintf dprintf fprintf fscanf fwprintf fwscanf iovfscanf \
 		 isoc99_vscanf isoc99_vfscanf isoc99_vsscanf \
 		 isoc99_wscanf isoc99_fwscanf isoc99_swscanf \
 		 isoc99_vwscanf isoc99_vfwscanf isoc99_vswscanf \
+		 isoc23_scanf isoc23_fscanf isoc23_sscanf \
+		 isoc23_vscanf isoc23_vfscanf isoc23_vsscanf \
+		 isoc23_wscanf isoc23_fwscanf isoc23_swscanf \
+		 isoc23_vwscanf isoc23_vfwscanf isoc23_vswscanf \
 		 nextup nextdown totalorder totalordermag getpayload \
 		 canonicalize setpayload setpayloadsig llogb fmaxmag fminmag \
 		 roundeven fromfp ufromfp fromfpx ufromfpx fadd dadd \
@@ -221,3 +225,43 @@ $(objpfx)tst-nldbl-error.c: tst-ldbl-error.c
 CFLAGS-tst-nldbl-warn.c += -mlong-double-64
 CFLAGS-tst-nldbl-error.c += -mlong-double-64
 endif
+
+ifeq ($(subdir), stdio-common)
+tests += tst-nldbl-scanf-binary-c11 \
+	 tst-nldbl-scanf-binary-c2x \
+	 tst-nldbl-scanf-binary-gnu11 \
+	 tst-nldbl-scanf-binary-gnu89
+
+# Some versions of GCC supported for building glibc do not support -std=c2x, so
+# the test for that version uses -std=c11 and then _ISOC2X_SOURCE is defined in
+# the test as needed.
+CFLAGS-tst-nldbl-scanf-binary-c11.c += -mlong-double-64 -std=c11 \
+				       -DOBJPFX=\"$(objpfx)\"
+CFLAGS-tst-nldbl-scanf-binary-c2x.c += -mlong-double-64 -std=c11 \
+				       -DOBJPFX=\"$(objpfx)\"
+CFLAGS-tst-nldbl-scanf-binary-gnu11.c += -mlong-double-64 -std=gnu11 \
+					 -DOBJPFX=\"$(objpfx)\"
+CFLAGS-tst-nldbl-scanf-binary-gnu89.c += -mlong-double-64 -std=gnu89 \
+					 -DOBJPFX=\"$(objpfx)\"
+
+endif
+
+ifeq ($(subdir), wcsmbs)
+tests += tst-nldbl-wscanf-binary-c11 \
+	 tst-nldbl-wscanf-binary-c2x \
+	 tst-nldbl-wscanf-binary-gnu11 \
+	 tst-nldbl-wscanf-binary-gnu89
+
+# Some versions of GCC supported for building glibc do not support -std=c2x, so
+# the test for that version uses -std=c11 and then _ISOC2X_SOURCE is defined in
+# the test as needed.
+CFLAGS-tst-nldbl-wscanf-binary-c11.c += -mlong-double-64 -std=c11 \
+					-DOBJPFX=\"$(objpfx)\"
+CFLAGS-tst-nldbl-wscanf-binary-c2x.c += -mlong-double-64 -std=c11 \
+					-DOBJPFX=\"$(objpfx)\"
+CFLAGS-tst-nldbl-wscanf-binary-gnu11.c += -mlong-double-64 -std=gnu11 \
+					  -DOBJPFX=\"$(objpfx)\"
+CFLAGS-tst-nldbl-wscanf-binary-gnu89.c += -mlong-double-64 -std=gnu89 \
+					  -DOBJPFX=\"$(objpfx)\"
+
+endif