[bug#52499] [PATCH] gnu: Fix build error of libpfm4.

[Olivier Dion via Guix-patches via <guix-patches@gnu.org>]

For some reason, the build recently failed with:

        pfmlib_perf_event_pmu.c:349:36: error: ?%s? directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=]
          349 |   snprintf(d2path, MAXPATHLEN, "%s/%s", debugfs_mnt, d1->d_name);
              |                                    ^~
        pfmlib_perf_event_pmu.c:349:3: note: ?snprintf? output between 2 and 4352 bytes into a destination of size 4096
          349 |   snprintf(d2path, MAXPATHLEN, "%s/%s", debugfs_mnt, d1->d_name);
              |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        pfmlib_perf_event_pmu.c:399:58: error: ?%s? directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=]
          399 |                         snprintf(idpath, MAXPATHLEN, "%s/%s/id", d2path, d2->d_name);
              |                                                          ^~
        pfmlib_perf_event_pmu.c:399:25: note: ?snprintf? output between 5 and 4355 bytes into a destination of size 4096
          399 |                         snprintf(idpath, MAXPATHLEN, "%s/%s/id", d2path, d2->d_name);
              |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        cc1: all warnings being treated as errors

* gnu/packages/linux.scm (libpfm4): Fix build.
(%standard-phases) Add `-Wno-format-truncation` to CFLAGS in build phase.
---
 gnu/packages/linux.scm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gnu/packages/linux.scm b/gnu/packages/linux.scm
index c752df7996..a1c9408e89 100644
--- a/gnu/packages/linux.scm
+++ b/gnu/packages/linux.scm
@@ -7632,6 +7632,7 @@ (define-public libpfm4
                     (lambda* (#:key inputs outputs #:allow-other-keys)
                       (let* ((out (assoc-ref outputs "out")))
                         (setenv "CC" "gcc")
+                        (setenv "CFLAGS" "-Wno-format-truncation")
                         (invoke "make")
                         #t)))
                   (replace 'install
-- 
2.34.0