master 8c4498e62e: Avoid compiler warnings on macOS (bug#55595)

[Eli Zaretskii]

branch: master
commit 8c4498e62ed58ac94cc627d2ab085f2b17abc090
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Avoid compiler warnings on macOS (bug#55595)
    
    * configure.ac: Don't use -Wunknown-pragmas with Clang.
    
    * src/comp.c (load_comp_unit): Avoid Clang compilation warning.
---
 configure.ac | 1 +
 src/comp.c   | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 1d2d1f190b..ed8ec890ac 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1084,6 +1084,7 @@ AS_IF([test $gl_gcc_warnings = no],
 
   if test "$emacs_cv_clang" = yes; then
     nw="$nw -Wdouble-promotion"
+    nm="$nm -Wunknown-pragmas"
   fi
 
   # This causes too much noise in the MinGW build.
diff --git a/src/comp.c b/src/comp.c
index b01106c906..2b9808aba6 100644
--- a/src/comp.c
+++ b/src/comp.c
@@ -5342,7 +5342,7 @@ load_comp_unit (struct Lisp_Native_Comp_Unit *comp_u, 
bool loading_dump,
         are necessary exclusively during the first load.  Once these
         are collected we don't have to maintain them in the heap
         forever.  */
-      Lisp_Object volatile data_ephemeral_vec;
+      Lisp_Object volatile data_ephemeral_vec = Qnil;
       /* In case another load of the same CU is active on the stack
         all ephemeral data is hold by that frame.  Re-writing
         'data_ephemeral_vec' would be not only a waste of cycles but