[glibc/azanella/clang] elf: Supress clang -Wsometimes-uninitialized on _dl_debug_initialize

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a3ccba50e36f29383cf2af8147e17c347426e1f5

commit a3ccba50e36f29383cf2af8147e17c347426e1f5
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Aug 24 12:25:05 2022 -0300

    elf: Supress clang -Wsometimes-uninitialized on _dl_debug_initialize
    
    clang issues an warning where variable 'r' is used uninitialized
    whenever 'if' condition is false.  The _dl_debug_initialize is called
    for static case always with LM_ID_BASE (csu/libc-start.c and
    elf/dl-reloc-static-pie.c) and DL_NSS will be always larger than 1
    for shared case.

Diff:
---
 elf/dl-debug.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/elf/dl-debug.c b/elf/dl-debug.c
index 5ff1460ab7..5a4c0613f7 100644
--- a/elf/dl-debug.c
+++ b/elf/dl-debug.c
@@ -17,6 +17,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <ldsodefs.h>
+#include <libc-diag.h>
 
 
 /* These are the members in the public `struct link_map' type.
@@ -54,7 +55,15 @@ _dl_debug_update (Lmid_t ns)
 struct r_debug *
 _dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
 {
-  struct r_debug_extended *r, **pp = NULL;
+  /* clang issues an warning where variable 'r' is used uninitialized whenever
+     'if' condition is false.  The _dl_debug_initialize is called for static
+     case always with LM_ID_BASE (csu/libc-start.c and
+     elf/dl-reloc-static-pie.c) and DL_NSS will be always larger than 1 for
+     shared case.  */
+  DIAG_PUSH_NEEDS_COMMENT_CLANG;
+  DIAG_IGNORE_NEEDS_COMMENT_CLANG (18, "-Wsometimes-uninitialized");
+  struct r_debug_extended *r;
+  struct r_debug_extended **pp = NULL;
 
   if (ns == LM_ID_BASE)
     {
@@ -81,6 +90,7 @@ _dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
 	  r->base.r_version = 2;
 	}
     }
+  DIAG_POP_NEEDS_COMMENT_CLANG;
 
   if (r->base.r_brk == 0)
     {