It turns out the bug was much simpler. The argc decrement operators got
inverted to increment.
On Sun, Jul 26, 2026 at 9:28 PM Trent Tanchin <[email protected]> wrote:
> Hello,
>
> There appears to be a change in the way the ARG_* macros' processing works
> that causes build failures in some packages that use bison with versions of
> m4 starting at commit 93efdeeb.
>
> An example on my custom linux system (loosely based on LinuxFromScratch)
> building glibc-2.43 with gcc-16.1.0:
> gcc /usr/src/glibc-2.43/build/intl/plural.c -c -std=gnu11 -fgnu89-inline
> -g -O2 -Wall -Wwrite-strings -Wundef -Wimplicit-fallthrough
> -fmerge-all-constants -frounding-math -ftrapping-math
> -fstack-protector-strong -fno-common -U_FORTIFY_SOURCE -Wstrict-prototypes
> -Wold-style-definition -Wfree-labels -Wmissing-parameter-name -fmath-errno
> -fPIE -ftls-model=initial-exec -I../include
> -I/usr/src/glibc-2.43/build/intl -I/usr/src/glibc-2.43/build
> -I../sysdeps/unix/sysv/linux/x86_64/64 -I../sysdeps/x86_64/64/nptl
> -I../sysdeps/unix/sysv/linux/x86_64/include
> -I../sysdeps/unix/sysv/linux/x86_64
> -I../sysdeps/unix/sysv/linux/x86/include -I../sysdeps/unix/sysv/linux/x86
> -I../sysdeps/x86/nptl -I../sysdeps/unix/sysv/linux/wordsize-64
> -I../sysdeps/x86_64/nptl -I../sysdeps/unix/sysv/linux/include
> -I../sysdeps/unix/sysv/linux -I../sysdeps/nptl -I../sysdeps/pthread
> -I../sysdeps/gnu -I../sysdeps/unix/inet -I../sysdeps/unix/sysv
> -I../sysdeps/unix/x86_64 -I../sysdeps/unix -I../sysdeps/posix
> -I../sysdeps/x86_64/64 -I../sysdeps/x86_64/fpu/multiarch
> -I../sysdeps/x86_64/fpu -I../sysdeps/x86/fpu
> -I../sysdeps/x86_64/multiarch -I../sysdeps/x86_64
> -I../sysdeps/x86/include -I../sysdeps/x86 -I../sysdeps/ieee754/float128
> -I../sysdeps/ieee754/ldbl-96/include -I../sysdeps/ieee754/ldbl-96
> -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32
> -I../sysdeps/wordsize-64 -I../sysdeps/ieee754 -I../sysdeps/generic -I..
> -I../libio -I. -D_LIBC_REENTRANT -include
> /usr/src/glibc-2.43/build/libc-modules.h -DMODULE_NAME=libc -include
> ../include/libc-symbols.h -DPIC -DTOP_NAMESPACE=glibc
> -D'LOCALEDIR="/usr/share/locale"' -D'LOCALE_ALIAS_PATH="/usr/share/locale"'
> -Wno-unused-but-set-variable -Wno-implicit-fallthrough -o
> /usr/src/glibc-2.43/build/intl/plural.o -MD -MP -MF
> /usr/src/glibc-2.43/build/intl/plural.o.dt -MT
> /usr/src/glibc-2.43/build/intl/plural.o
> /usr/src/glibc-2.43/build/intl/plural.c:160:17: error: stray ‘\33’ in
> program
> 160 | YYEOF = 0,PU<U+001B><d1><U+0015>V /* "end of
> file" */
> | ^~~~~~~~
> /usr/src/glibc-2.43/build/intl/plural.c:160:18: error: stray ‘\321’ in
> program
> 160 | YYEOF = 0,PU<U+001B><d1><U+0015>V /* "end of
> file" */
> | ^~~~
> /usr/src/glibc-2.43/build/intl/plural.c:160:19: error: stray ‘\25’ in
> program
> 160 | YYEOF = 0,PU<U+001B><d1><U+0015>V /* "end of
> file" */
> | ^~~~~~~~
> /usr/src/glibc-2.43/build/intl/plural.c:160:20: error: expected ‘,’ or ‘}’
> before ‘V’
> 160 | YYEOF = 0,PUV /* "end of file" */
> | ^
> /usr/src/glibc-2.43/build/intl/plural.c:161:21: error: stray ‘\33’ in
> program
> 161 | YYerror = 256,PU<U+001B><d1><U+0015>V /* error */
> | ^~~~~~~~
> /usr/src/glibc-2.43/build/intl/plural.c:161:22: error: stray ‘\321’ in
> program
> 161 | YYerror = 256,PU<U+001B><d1><U+0015>V /* error */
> | ^~~~
> /usr/src/glibc-2.43/build/intl/plural.c:161:23: error: stray ‘\25’ in
> program
> 161 | YYerror = 256,PU<U+001B><d1><U+0015>V /* error */
> | ^~~~~~~~
> /usr/src/glibc-2.43/build/intl/plural.c:162:21: error: stray ‘\33’ in
> program
> 162 | YYUNDEF = 257,PU<U+001B><d1><U+0015>V /* "invalid
> token" */
> | ^~~~~~~~
> /usr/src/glibc-2.43/build/intl/plural.c:162:22: error: stray ‘\321’ in
> program
> 162 | YYUNDEF = 257,PU<U+001B><d1><U+0015>V /* "invalid
> token" */
> | ^~~~
> /usr/src/glibc-2.43/build/intl/plural.c:162:23: error: stray ‘\25’ in
> program
> 162 | YYUNDEF = 257,PU<U+001B><d1><U+0015>V /* "invalid
> token" */
> | ^~~~~~~~
> ...
>
> This is the build command that generates the file:
> bison --yacc --no-lines --name-prefix=__gettext --output
> /usr/src/glibc-2.43/build/intl/plural.c plural.y
>
> This byte pattern repeats many times over throughout plural.c, and every
> build produces different random bytes. Reverting 93efdeeb fixes the issue,
> although format.c has been edited since that commit, so attached is a patch
> file for branch-4.1 current HEAD (commit 63e4afd3) effectively reverting
> it. I have tried both the latest release of bison (3.8.2) and the latest
> TOT (3.8.2.75-089c). This also occurs on glibc TOT and flex TOT (although
> not the latest release).
> I am not sure why it does this, but hopefully this provides enough
> information to fix it in a way that also incorporates the purpose of
> commit 93efdeeb.
>
> -Trent Tanchin
>
--- m4/src/format.c.orig 2026-07-26 23:14:22.325699192 -0400
+++ m4/src/format.c 2026-07-26 23:14:32.622349940 -0400
@@ -118,11 +118,11 @@
#define ARG_STR(argc, argv) \
(((argc) == 0) ? "" : \
- ((argc)++, TOKEN_DATA_TEXT (*(argv)++)))
+ ((argc)--, TOKEN_DATA_TEXT (*(argv)++)))
#define ARG_DOUBLE(argc, argv) \
(((argc) == 0) ? 0 : \
- ((argc)++, arg_double (TOKEN_DATA_TEXT (*(argv)++))))
+ ((argc)--, arg_double (TOKEN_DATA_TEXT (*(argv)++))))
/* Parse a width or precision from FMT's prefix.
If FMT[-1] == '.' this is a precision instead of a width.
