Hi,
I saw this bug older than 7 days and no maintainer activity, but it
fixed upstream:
https://github.com/canonical/lightdm/commit/270b3bfcf84939ab2d71db3f3470cffd36816852
So I prepared a debdiff, and I hope this will help.
Cheers,
handsome_feng
diff -Nru lightdm-1.26.0/debian/changelog lightdm-1.26.0/debian/changelog
--- lightdm-1.26.0/debian/changelog 2020-02-04 03:13:13.000000000 +0800
+++ lightdm-1.26.0/debian/changelog 2022-01-06 14:49:08.000000000 +0800
@@ -1,3 +1,12 @@
+lightdm (1.26.0-7.1) UNRELEASED; urgency=medium
+
+ * Non-maintainer upload.
+ * debian/patches:
+ - 10_fix-build-glibc-2.33 added, fix FTBFS with glibc 2.33.
+ (Closes: #1002132)
+
+ -- handsome_feng <jianfen...@ubuntukylin.com> Thu, 06 Jan 2022 14:49:08 +0800
+
lightdm (1.26.0-7) unstable; urgency=medium
[ Debian Janitor ]
diff -Nru lightdm-1.26.0/debian/patches/10_fix-build-glibc-2.33.patch
lightdm-1.26.0/debian/patches/10_fix-build-glibc-2.33.patch
--- lightdm-1.26.0/debian/patches/10_fix-build-glibc-2.33.patch 1970-01-01
08:00:00.000000000 +0800
+++ lightdm-1.26.0/debian/patches/10_fix-build-glibc-2.33.patch 2022-01-06
14:49:08.000000000 +0800
@@ -0,0 +1,22 @@
+--- a/tests/src/libsystem.c
++++ b/tests/src/libsystem.c
+@@ -329,6 +329,10 @@ stat64 (const char *path, struct stat64
+ return _stat64 (new_path, buf);
+ }
+
++// glibc 2.33 and newer does not declare these functions in a header file
++#pragma GCC diagnostic push
++#pragma GCC diagnostic ignored "-Wmissing-prototypes"
++
+ int
+ __xstat (int version, const char *path, struct stat *buf)
+ {
+@@ -365,6 +369,8 @@ __fxstatat64(int ver, int dirfd, const c
+ return ___fxstatat64 (ver, dirfd, new_path, buf, flags);
+ }
+
++#pragma GCC diagnostic pop
++
+ DIR *
+ opendir (const char *name)
+ {
diff -Nru lightdm-1.26.0/debian/patches/series
lightdm-1.26.0/debian/patches/series
--- lightdm-1.26.0/debian/patches/series 2020-02-04 03:13:13.000000000
+0800
+++ lightdm-1.26.0/debian/patches/series 2022-01-06 14:49:08.000000000
+0800
@@ -5,3 +5,4 @@
06_change-user-dirs.patch
08_reset-SIGPIPE-before-exec.patch
09_hide_systemd_nologin.patch
+10_fix-build-glibc-2.33.patch
